Car is running lean on light throttle - any ideas?

[TAR]

I have an issue with my car running lean which may or may not be a problem. Any thoughts happily accepted.


The car has standard ecu, panel filter, 3" exhaust from turbo's back, standard intercooler, Walboro 533lph fuel pump, Sytec fuel pressure regulator (set correctly) and connected to vacuum line. I always run Tesco Momentum 99 octane fuel and have just installed reconditioned standard fuel injectors and new NGK BK7EIX spark plugs. \its currently got the cat fitted but I have experienced the same issue with a decat.

The car generally idles when cold at about 16 afr which gradually drops as the engine warms up, once warm at idle its running 14.7 or thereabouts.


If cruising just off boost, the afr's are perfect at 14.7 ish but if I put my foot down a little bit, such as to keep my speed up a slight incline, or hill, or just to overtake a slower car it shoots up to 16.5 and on occasion I have seen it as high as 17. Soon as I lift off its OK and also if I floor it to WOT, the afr's drop as expected. Its only on light throttle that I see the car leaning out.


On the rollers at Ben's last year he told me it was a bit lean and the spark plugs when changed were quite a light brown colour, just a bit too light for my liking.


I'm not sure what is going on but I don't initially think its an air leak as it would potentially affect the afr's at any boost and this only happens on light throttle?

Last thing worth mentioning is that the return to idle can be a bit lazy on occasion where it will idle at around 1000 rpm when warm.

:happy:

[adaxo]

Its may been done, but may worth to mention, what about fuel filter?

[Humpty's Revenge]

Why is the car running lean from cold?

[Davezj]

my car is exaxtly the same, and so is adams if i remember rightly, on the idle front anyway.
My car starts from cold on idle and runs at about 15.5-16:1 AFR until the idle speed starts to drop from 1500rpm to the normal 650rpm. takes about 4-5 mins of just idle to warm up and drop back to normal.

when cruising at 70mph 14.7:1 AFR put my foot down slightly and i maean slightly, only enough to accelerate to 80mph very slowly AFR goes up to about 15.7-16:1 AFR, put it down any harder and AFR drops back to 14.7:1 and below.
i have a feeling it is entering a portion of the the fuel map in the ECU which is supposed to super economical.
you should be able to see the area of the fuel map that you are entering, very light load value, with rpm about 3000, if you use ECUflash.

i don't think there is anything wrong or out of the ordinary, apart from,

WHAT ARE YOU DOING PRESSING THE ACCELERATOR THAT LIGHTLY, SHAME ON YOU.

yes i was shouting LOL.

[Nick Mann]

I'm hoping to have a tinker with mine tomorrow if I get time - to try to increase the boost a bit before saturday. I'll try and notice what occurs.

[Humpty's Revenge]

my car is exaxtly the same, and so is adams if i remember rightly, on the idle front anyway.
My car starts from cold on idle and runs at about 15.5-16:1 AFR until the idle speed starts to drop from 1500rpm to the normal 650rpm. takes about 4-5 mins of just idle to warm up and drop back to normal.

when cruising at 70mph 14.7:1 AFR put my foot down slightly and i maean slightly, only enough to accelerate to 80mph very slowly AFR goes up to about 15.7-16:1 AFR, put it down any harder and AFR drops back to 14.7:1 and below.
i have a feeling it is entering a portion of the the fuel map in the ECU which is supposed to super economical.
you should be able to see the area of the fuel map that you are entering, very light load value, with rpm about 3000, if you use ECUflash.

i don't think there is anything wrong or out of the ordinary, apart from,

WHAT ARE YOU DOING PRESSING THE ACCELERATOR THAT LIGHTLY, SHAME ON YOU.

yes i was shouting LOL.

Those figures don't look that good TBH??

OK my Skyline is different but still has 6 cylinders which are told what to do via an ecu & albeit a different set up but mine reads the following:-

From cold start is 11.7

Tick over @ 650rpm is 15.4 - 16.2

Driving normally @40 - 60 mph is around 14.1

WOT is 11.6 - 12.2

That looks to me that the vr4 engine runs lean in general maybe ??

[Davezj]

as soon as i plant my foot i am down in the 10's low 11's AFR straight away, my car runs rich most of the time, only ever goes marginly lean is in the above condition.

[Humpty's Revenge]

as soon as i plant my foot i am down in the 10's low 11's AFR straight away, my car runs rich most of the time, only ever goes marginly lean is in the above condition.


Silly question but why are these engines running so lean when cold?

Surely it should be richer when cold then leaning of once the temperature starts to rise slowly ?

[swinks]

Tim, your assumptions are right, i should run 12.5 - 13 ish afr on cold startup.
I guess there may be some air leak past maf, before turbos, not significant but affecting low idle revs.

[Davezj]

there is a temperature enrichment table in the ecu so yes it does sound like should be richer at initial warn up but my car has always been lean at initial start up.
and i know adams is the same.
The dash temp works OK and this is driven from the small single wire temp sensor on the thermostat water manifold the ECU does not know about this temp sensor.
the other temp sensor on the thermostat manifold is the one the ECU knows about and if i can log coolant temp with evoscan then it must be OK.
so what does this tell me?
the premier enrichment table must not be being looked at for some reason, i don't know why.
i have a innovate MTX-L wideband.
maybe the calibation is off on the AFR gauge is out, i re did it about a month or so ago, by disconnecting the wideband from the gauge power up the gauge which deletes the calibration, switch off the gauge reconnect the wideband power up the gauge so it does the calibration. then switch it off to save the calibration then start the car, and the gauge should be colibratied.
the only thing i did not do was remove the wideband from the exhaust pipe. i figured the car had been left all night so there would be only fresh air in the exhaust pipe, so it would be OK.
do you think this could be wrong.
but this would mean adams and tims gauge setups must be the same as mine.

if i blip the throttle when cold then the AFR comes down to 14.7:1 much quicker in about 30seconds, but if you just start it and let it idle then it always goes lean for the first few minutes until it idle drops to 650 and 14.7:1 AFR.

i will try and recallibrating it tomorrow morning

[TAR]

Thanks for the replies guys....

Adam - fuel filter not that old but I have another one to fit soon.

Dave - you appear to have a similar scenario.

Steve - no idea why its running lean on cold start.

I wondered if I had a lazy lambda sensor, I suppose I could prove that by hooking up the narrowband emulatipon from the wideband.

Its very odd but great for fuel conservation!

Tomaz - I will have another look for a leak, but I'm pretty sure I dont have one, unless the butterfly is worn? I think someone on OZVR4 found an issue with that?
:happy:

[swinks]

Tim, I meant air leak between maf and turbo, low pressure one. Only that one may give similar symptoms. Typical when rubber 3-way splitter is worn or not tighten up enough. That will give you lean idle and rough low revs.

[mike74]

a dodgy engine temperature sensor could give a similar symptom, couldn't it? ie when engine is cold it actually thinks its hot and doesn't put as much fuel in

[Nick Mann]

To confirm, my car doesn't do this!

[Davezj]

what does it do nick?
Is it the same as tomasz, and go rich down to about 14:1 then as the coolant temp rises it goes back to 14.7:1
this is assuming you just start the car and do not rev it at all, just let it idle until it comes up to temperature.

a leak in the MAF to turbo inlet pipework.
or a faulty temp sensor.
seem reasonable causes, is there anything else?

[fassi1]

there is a temperature enrichment table in the ecu so yes it does sound like should be richer at initial warn up but my car has always been lean at initial start up.
and i know adams is the same.
The dash temp works OK and this is driven from the small single wire temp sensor on the thermostat water manifold the ECU does not know about this temp sensor.
the other temp sensor on the thermostat manifold is the one the ECU knows about and if i can log coolant temp with evoscan then it must be OK.
so what does this tell me?
the premier enrichment table must not be being looked at for some reason, i don't know why.
i have a innovate MTX-L wideband.
maybe the calibation is off on the AFR gauge is out, i re did it about a month or so ago, by disconnecting the wideband from the gauge power up the gauge which deletes the calibration, switch off the gauge reconnect the wideband power up the gauge so it does the calibration. then switch it off to save the calibration then start the car, and the gauge should be colibratied.
the only thing i did not do was remove the wideband from the exhaust pipe. i figured the car had been left all night so there would be only fresh air in the exhaust pipe, so it would be OK.
do you think this could be wrong.
but this would mean adams and tims gauge setups must be the same as mine.

if i blip the throttle when cold then the AFR comes down to 14.7:1 much quicker in about 30seconds, but if you just start it and let it idle then it always goes lean for the first few minutes until it idle drops to 650 and 14.7:1 AFR.

i will try and recallibrating it tomorrow morning

The problem is that ECU stays in open loop and doesn't want to switch to closed loop and you get AFR more than 14.7,
Look at oxygen fuel trim when lean it's 0%.
As you tap accelerator it suddenly goes in to closed loop and targets AFR 14.7 as well as oxygen fuel trim
starts working.
I don't know why doesn't it want to go in to closed loop when oxygen sensor is warm and ready
like most ECUs I had experience with do.

[TAR]

Tomaz - I will have another look at that pipe.

Nick - thanks for checking.

Does anyone know at what point the ecu switches to open loop? is it rpm based, tps or something else?

:happy:

[Nick Mann]

I have been playing a bit today with ECU flash and I am under the impression that it is based on TPS vs RPM. i.e. if tps is over x value when rpm is over y value, ecu will switch to open loop.

[Davezj]

Right let me tell you what I have found out and what I think might have happend to cause it.

Well I did not recalibrate my wideband sensor before going to work today, I did it when I left work this afternoon. I did not remove the sensor worm the exhaust.
So I did the calibration of the MTX-L ,
Disconnect the sensor from gauge
Turn ignition on for 30 sec.
Switch ignition off.
Reconnect sensor to gauge
Switch on ignition wait for htr to flick to cal and wait until gauge reads 22.5:1 AFR.
Switch off ignition
Start engine

This what to the AFR over the period of 20 seconds,
10.6:1
11.6:1
13:1
14:1
Next 30 seconds
14:1
14.1:1
14.2:1
14.4:1
14.5:1
14.7:1

So after a the calibration was carried out my car seems to be acting the same as nicks and tomasz cars.

Now for the reason why my calibration was out.

Last time I calibrated the MTX-L it was first thing in the morning and I did not remove the sensor from the exhaust as it was left over night and the gases around the sensor would have dispersed to fresh air over night, I have no doubt of that.
But it was quite damp and cold, so I can surmise the sensor in the exhaust could have been covered in water vapour/dew or the air in the exhaust was just very dense and it could be this that has made my last calibration incorrect.

What do you think to my theory, does it sound plausible?

[fassi1]

I had my MTX-L calibrated in dry air environment and got it fited in my car.
After having AFR gauge fited noticed the same problem which is lean idle mixture.
Some time ago recalibrated MTX-L the same way you did it Dave leaving the car over night and nothing changed.
ECU notices too much air while in closed loop and tries to adjust fueling to hit about 14.7
ECU stayes in closed loop as long as fuel trim in use (long term fuel trim) doesn't exceed about 4.69.. % as far as i remember
and oxygen fuel trim (short term fuel trim) doesn't exceed about 16.7.. %.
If these limits are achieved, ECU switches to open loop and uses fixed fuel trim in use 5% and at that moment AFR starts increasing and we are getting lean idle.
As soon as we tap the accelerator ECU will start everything again.
The question is what causes it, is it wrong TPS signal, air leak, wrong MAF signal ?????
Pezza's new leggy seems to be fine cause idle fuel trim in use (long term fuel trim) < 4.69.. % which means there is still some room for adjustments in case leaner mixture. Didn't have enough time to compare other live values with my leggy.

[Davezj]

Interesting stuff chris, but when you recalibrated the gauge was it warm weather or a cold damp morning.

[SEAN-NZ]

a dodgy engine temperature sensor could give a similar symptom, couldn't it? ie when engine is cold it actually thinks its hot and doesn't put as much fuel in

dodgy temp sensor should make the ecu think engines cold, because when sensor is cold it has a much higher resistance, when it warms up the resistance drops, in my experience when its stuffed it maintains a high resistance, does drop as it wamrs up, but doesnt get as low as it should have, in my case it caused the car to drink petrol, didnt matter how i drove, also cut when i put foot down a bit to far, was worse when cold than when warm

[fassi1]

Interesting stuff chris, but when you recalibrated the gauge was it warm weather or a cold damp morning.
It was just before Christmas so it was rather cold and damp morning.

[Davezj]

something must have gone wrong with my calibration last time, i am just clutching at straws to find a reason.

but on the plus side rchecckdit thhis morning an it does the rich to normal gradual trasition.
Sorry tim i know this ddoes not help you.

just out on interest tim have you recalibrated you gaauge recently, it might be worth doing.

[TAR]

not calibrated for a while and I will do it however, regardless of whether is reading wrong, its the sudden change in gauge reading which is confusing me. And my plugs are showing signs of running lean as well.

I will re calibrate but I don't think it will make any difference (may just move the readings up or down the scale)

:happy:

[Davezj]

just one thing to cross off the list of suspect.

[lateshow]

Hey guys this is rather normal and is due to the fact that factory has scaled the injectors so that LTFT maxxes out -> meaning that the scaling IS too big and if you set the car to open loop it doesnt get enought gasoline. I've been messing about with injector scaling. The original value was 400 with my new method and now I'm down to 350 or something and long fuel trim sails between 1-3,5.... And i can say: No more lean spots but car feels lazier. Yes I get about the same AFR i want in open loop but acceleration enrichment gives me a dip to the rich side when i even press my foot a tiny amount down. There has to be some kind of compromise for that but since I will be tuning for etnahol soon (actually flexifuel) I will buy bigger 670cc injectors.

By the way, a middle trim has been discovered! Or a way to use it, I currently am running with middle trim and low trim just as in Evo5. Ceddy/Ralliart have this switched off. The only problem is that no matter i do with the hi -> mid limits, trim wont go off in full throttle.

[TAR]

Lauri - thanks for your advice. I've read it twice now and think I get what you are saying :happy:

[fassi1]

Hmmm so we r back to the fuel trims :)
VR4 has so little adjustment range (-5%, +5%) in comparison to V6 N/A
and truth stays in closed loop only at low load (vacuum) and as soon as is in boost goes in to open loop
so mid load and high load fuel trims are disabled.

[Humpty's Revenge]

Also a quick note

If you are still running your cat the readings from the afr gauge will read richer due to build up of gasses not escaping fast enough

[TAR]

I've currently still got the cat fitted as I forgot to remove it after the last MOT.

I'm seeing the car lean out whilst in vacuum (so long as my boost guage is accurate) and it gets worse as it comes onto boost. A harder press of the throttle will cause it to richen up a bit but as soon as I ift off again it shoots back up to 16. something.
I've also now noticed that occasionally when I start the car if its warm, I'm straight into 17's and it appears to missfire, which must be the timing getting pulled. This only happens occasionally and must be closed loop. I am going to use the narrowband emulation from the wideband to check if my lambda sensor is going faulty.

:happy:

[Davezj]

tim do you have two O2 sensors fitted?
the wideband and the original factory narrow band.
if you only have the one wideband sensor fittted the narrow band output of the AFR gauge needs to go in to the ECU.

or were you going to check the narrow band output with evoscan to see it bounce up and down from 0-1V.

just ramblinng

[TAR]

Dave - I have 2 lambda sensors, the OEM narrowband one and the wideband one.

I suspect that the OEM narrowband sensor is playing up, so I'm going to use the AFR gauge narrowband emulation to input to the car's ecu.

:happy:

[Davezj]

aahhh, very clever.

that should give you a result one way or the other.

[mike74]

So when the engine's pulling vacuum you're seeing the AFR shoot up & when you boot it, it goes rich? To me, that sounds like you've got an air leak somewhere

[fassi1]

Having 17's ECU is definitely in open loop.
I had cat on for while after MOT and didn't notice any difference.

[Nick Mann]

I'd thoroughly recommend narrowband emulation anyway. Both the VR4's I have done that to have improved slightly on fuel consumption.

[fassi1]

Which injector scaling does ECU use?
I have:
EVO (Untested) 375cc/min
DSM (Untested) 409cc/min
What does untested mean???

[fassi1]

I was playing with my occasionl lean idle. Checked all the pipes and connections from MAF to the tubes, everything looked fine to me.
Decided to play with injector scaling.
Having DSM scaling 409 changed that to 380, didn't make any difference to STFT and LTFT.
Changed 380 to 359 and still no change at all.
LTFT 4.6875
STFT about 14
:rolleyes4 why is there no change to STFT and LTFT?
Am I beeing thick?

[Davezj]

i think injector scaling relies on something else in the ecu other than the figure you input.

i can't remeber what it is, but it rings a bell,
how ever i don't know if that bell is reliable or not as i have had quite a lot of guinees tonight.
i am in training for a 2 week holiday in august to southern ireland.

[TAR]

thanks for keeping this thread alive Dave.... and enjoy the Guinness

Not had time to look at anything on the car, but please keep the ideas coming.

:happy:

[fassi1]

Unless injector scaling address needs to be changed aswell as injector scaling figure.

[lateshow]

10306 is the right address for injector scaling!

[fassi1]

At xml definition injector scaling address 10318,
ROM injector scaling address 10318
Hmmm both are the same.
Do both need to be changed to 10306?

[fassi1]

Big thanks to lateshow and foxdie for helpful advices.
Finally managed to sort out occasional lean idle.
Having injector size scaling DSM 409 and injector size scaling address 10318 in xml definition file vr4base.xml
changed injector size scaling DSM to 376 (that gives EVO 344) and injector size scaling address to 10306 in vr4base.xml file, injector size scaling address has been changed automaticly to 10306 in rom file.
As merlin stated eddress value is an important air flow parameter.
http://www.clubvr4.com/forum/showthread.php?59218-560cc-EVO-injectors-vs-ECUFlash&highlight=injector+scaling
Quick rom upload and straightaway noticed that around 10% been knocked off of the STFT which gave me 5-7%, LTFT remained 4.6875%.
Other thing I noticed is richer open loop which is now very close to stock fuel maps.
Borat would say "Great success" /Banana
Dave that bell was reliable

[TAR]

LOL Chris... glad you got yours sorted, just wish I could get mine working as well.:happy:

[Davezj]

Chris fassi1 lateshow does this mean that the injector scaling address is wrong in avert bodies def file.
Are you using Kenneth's rom and def file, or you using a home grown one of you own.
Does Kenneth's rom need to be updated.

[fassi1]

Im using home xml definition which had injector scaling address 10318. I edited it and changed address to 10306.
ROM I'm using is the one i read from my ECU and the only thing I changed is injector size scaling to 376.
I didn't use Kenneth's ROM.

[lateshow]

Chris fassi1 lateshow does this mean that the injector scaling address is wrong in avert bodies def file.
Are you using Kenneth's rom and def file, or you using a home grown one of you own.
Does Kenneth's rom need to be updated.
yes the original vr4base has the wrong value, atleast in 20030013 has 10306 and many others. Kenneth's definition has this one right as it is 20030013 based mod.

[Davezj]

cheers chris, thanks for the info.

[fassi1]

Just gone through warm up process. Cold start and left it idling for about half an hour.
LTFT remained 4.6875% like before rescaling which is maximum but STFT started from around -2% and was getting higher with engine getting warmer reaching the highest around 9%. That means scaling still could be lower than 376.
Looks like most of this cars suffer from high positive fuel trims, remember pezza's VR4 had high positive LTFT and STFT but still within the range to keep it in closed loop
with AFR 14.7.

[disco-ian]

Hi all,
OK when I first bought my car I had similar issues (obviously I only knew about them when I fitted the AFR) I was dipping to 18's and 19's when at low rpm cruise.

Turned out to be the air flow meter. Not sure if you have a spare there to try but might be worth ago.

I also had the car cut out on me at low rpm a couple of times when we were in the extreme summer heat we got a little of last year and again changing the air flow meter fixed this.

[TAR]

I finally had some time to try a few things out but it gave me even more grief!!

To begin with I replumbed the vacuum line to the FPR as it was looking a bit suspect - no change
Reset the FPR to ensure it was correct - no change
Changed the MAF - no change
Tested the TPS and reset the IPS - no change
Changed the stock narrowband lambda sensor - no change

Then, all of a sudden, it started to run 17.7 to 18 all the time, except on boost when t dropped to 14's - WTF! the car was running like a dog, so I rechecked everything I had done and reset my wideband just in case, but nothing made any difference.

By this point I was very frustrated.

I have now spent the weekend trying to see what's going on. Looking at Evoscan, I could only see 0.03V to 0.05V for the O2 sensor, this didn't fluctuate much either. I checked the wiring and also wired in the narrowband emulation from the wideband but it still didn't make any difference. I was scratching my head now and getting very hot.

I then checked what would happen to the lambda if I disconnected the MAF as I know it should over fuel like mad..... and it did, but the O2 reading in Evoscan still didn't fluctuate very much, it certainly didn't hit 1.1V at any point. The fact it now ran rich proved the fuel delivery and the ECU's ability to fire the injectors sufficiently.

I connected everything back together and tried revving the nuts off it... don't know why but it seemed like a good idea at the time.

Disgruntled, I locked the car up and walked away.

A few hours later and back in the car, strat it up and BINGO!! its running just as it should without leaning out and idling at 14.5 to 15.1.

I have no idea what has happened but I'm really hoping it lasts more than 5 minutes. It's now running with the narrowband emulation, which I'm not really happy with as I'd rather run the stock O2 sensor but I'm too scared to swap it back!!

If anyone has any theories why this has happened... you know what to do

:happy: but very hot and now very sunburned.

[Davezj]

Good round up, glad you remembered to update this thread.

Could you have had a sticking valve or blocked injector, o2 sensor or some thing like that, that has now cleared itself.

I personally do an Italian tune up (5000rpm in 2nd or 3rd for a couple of miles done the road) every so often to clear out the pipes, I don't do many miles and the car is hardly up to temp when I get to work in the morning.

Just a thought.

[wintertidenz]

I had really weird problems with my Innovate wideband - it liked to lose calibration, which would make the car run super rich one time, and then another time way too lean.
I figured out after I removed it that the turbo timer was causing a power loss for a fraction of a second, and upsetting the calibration - it may be worth checking if this is the case.

[adaxo]

I finally had some time to try a few things out but it gave me even more grief!!

To begin with I replumbed the vacuum line to the FPR as it was looking a bit suspect - no change
Reset the FPR to ensure it was correct - no change
Changed the MAF - no change
Tested the TPS and reset the IPS - no change
Changed the stock narrowband lambda sensor - no change

Then, all of a sudden, it started to run 17.7 to 18 all the time, except on boost when t dropped to 14's - WTF! the car was running like a dog, so I rechecked everything I had done and reset my wideband just in case, but nothing made any difference.

By this point I was very frustrated.

I have now spent the weekend trying to see what's going on. Looking at Evoscan, I could only see 0.03V to 0.05V for the O2 sensor, this didn't fluctuate much either. I checked the wiring and also wired in the narrowband emulation from the wideband but it still didn't make any difference. I was scratching my head now and getting very hot.

I then checked what would happen to the lambda if I disconnected the MAF as I know it should over fuel like mad..... and it did, but the O2 reading in Evoscan still didn't fluctuate very much, it certainly didn't hit 1.1V at any point. The fact it now ran rich proved the fuel delivery and the ECU's ability to fire the injectors sufficiently.

I connected everything back together and tried revving the nuts off it... don't know why but it seemed like a good idea at the time.

Disgruntled, I locked the car up and walked away.

A few hours later and back in the car, strat it up and BINGO!! its running just as it should without leaning out and idling at 14.5 to 15.1.

I have no idea what has happened but I'm really hoping it lasts more than 5 minutes. It's now running with the narrowband emulation, which I'm not really happy with as I'd rather run the stock O2 sensor but I'm too scared to swap it back!!

If anyone has any theories why this has happened... you know what to do

:happy: but very hot and now very sunburned.
TAR, did you ever manage to find what was causing this problems as it behave very similar to my car atm

To avoid starting new thread I join here, if I may

Its used to happen occasionally that my car run lean on light/part throttle, but since I don't use it daily, rather once a week now, this issue become more common, to this degree that it's bad most of the time now. On idle afrs are mostly nice and steady (14ish) but sometimes it start leaning out to 18ish and car trying to stall then its some kind of a 'click' and all back to normal.

To be more precise, when cruising around on light load afr go up to 16-18, I assume only in closed loop as when I put my foot down its behave as it should, ie afrs drop to 11-12s.

So far I did this

swap MAF- no change
swap bov from forge to stock- no change
recalibrate wideband- no change, well it was normal for first few miles then start leaning out, then back to normal and again and again
check all vacuum/turbo pipes, all seems to be ok

Im getting annoyed and quite desperate to sort this out as I really want to go on RR day this sat, so any clues will help.

On the side note, I'm running Kenneth rom and something ring the bell in the back of my head that leaning issue was mentioned b4 by someone on here but cant find actual thread about, may foxdie mention this, I'm not sure.

Plan for next step is to flash my ecu with my original rom and see what's happen, is that make sense?

btw I've got evoscan logs but they about 6MB and are to big to upload here so if any one wants to see it I can send via email.

I try attach googledrive links let me know if they work, 12.11.08 is filr with issue present 13.17.34 is log when all was ok
https://drive.google.com/file/d/0BwmJdpWwLiO3WlBGLXo0UTFiSE0/edit?usp=sharing
https://drive.google.com/file/d/0BwmJdpWwLiO3aEhpUU8tRzJFQ1k/edit?usp=sharing

[foxdie]

Hi folks, coming into this quite late and trying to remember everything. My memory isn't what it once was ;)

Here are a my thoughts in bullet points;

* I believe the MTX-Ls need calibrating every 6 months, calibration needs to be done with a completely clean exhaust, leaving it standing overnight with no cat should suffice, if you have a cat you may need to try something more radical (calibrating it whilst on a long downhill stretch of road, low gear, engine revs steady above 3000 RPM with your foot off the accelerator so pure air is being pumped though)

* VR-4s do like to run a little lean but not that much. Raul used to regularly cycle between 13-18:1 AFR cruising under closed loop (hunting)

* Oxygen sensors typically have a 100,000 mile / 10 year life expectancy - don't trust it to be accurate if its anywhere near this age

* Faulty oxygen sensors typically result in richer running, not leaner running.

* Raul briefly used to run stupid lean (anything up to 20:1) when starting on a hot engine, always put this down to engine temp vs enrichment tables in the ECU not being set up properly, but as it sorted itself out after 30 seconds it wasn't a priority to fix it

* Starting him on cold would be around 11-12:1 until it warmed up, running rich on cold is only really programmed in to warm up the cat as soon as possible for emissions targets - the engines should be fine idling at stoich (14.7:1) from the get-go

* The software on the VR-4 ECU (and indeed most EFI cars) doesn't use the signal from the oxygen sensor for at least 20-30 seconds and then starts to dial it in slowly as both the sensor and engine temperatures approach working temp - ie. they run open loop for 20-30 seconds when the cars started, HOWEVER they do use the engine temp sensor for feedback and adjustment of fuelling

* Give or take a few other variables such as engine temp etc, the VR-4 ECUs will run closed loop until either the throttle is depressed beyond 50% or the engine load goes above 50% (whichever comes first), at which point it then switches to open loop

* A narrowband oxygen sensor has a sharp swing between 0.9 volts (+/- 0.1v) for about 14.5:1 and under, and about 0.1 volt (+/- 0.1v) for 14.9:1 and over. The ECU tries to meet stoich by repeatedly running rich and lean, crossing over that "line" on purpose to hunt for 14.7.

With the above bullet point in mind, logically one of three scenarios is happening:

1. Either the ECU is running open loop and the cell for that RPM vs LOAD value is out and needs adjusting (or like mentioned previously, injector scaling is out, however this is unlikely if you're running a stock ECU)
2. The narrowband output of the MTX-L is set too smoothly, resulting in slower response times for fuelling (again, doesn't sound likely)
3. If you're still using the stock narrowband for fuelling, its age could be resulting in slow reactions, making the ECU temporarily think the car is running richer than it is

These are just thinking out aloud, probably wrong on a few points, take it all with a pinch of salt :)

[adaxo]

Hi folks, coming into this quite late and trying to remember everything. My memory isn't what it once was

Here are a my thoughts in bullet points;

* I believe the MTX-Ls need calibrating every 6 months, calibration needs to be done with a completely clean exhaust, leaving it standing overnight with no cat should suffice, if you have a cat you may need to try something more radical (calibrating it whilst on a long downhill stretch of road, low gear, engine revs steady above 3000 RPM with your foot off the accelerator so pure air is being pumped though)- correct, manual says it should be done every 10000 miles, I did it by leaving car over night, no cat present

* VR-4s do like to run a little lean but not that much. Raul used to regularly cycle between 13-18:1 AFR cruising under closed loop (hunting)- it was ok b4, usually keep 14-15 all the time on light load

* Oxygen sensors typically have a 100,000 mile / 10 year life expectancy - don't trust it to be accurate if its anywhere near this age- i use only wideband which is about two years (~10000 mileas) old, emulate narrowband to ecu

* Faulty oxygen sensors typically result in richer running, not leaner running.- correct, when my narrow band connection fail car run richer than normal as ecu don't get lambda signal

* Raul briefly used to run stupid lean (anything up to 20:1) when starting on a hot engine, always put this down to engine temp vs enrichment tables in the ECU not being set up properly, but as it sorted itself out after 30 seconds it wasn't a priority to fix it- my afrs looks normal on hot/cold start, just leaning out after minute or so but not always

* Starting him on cold would be around 11-12:1 until it warmed up, running rich on cold is only really programmed in to warm up the cat as soon as possible for emissions targets - the engines should be fine idling at stoich (14.7:1) from the get-go- this how its now, start cold afrs are about 12-13 and then when warm up going to 14-15s

* The software on the VR-4 ECU (and indeed most EFI cars) doesn't use the signal from the oxygen sensor for at least 20-30 seconds and then starts to dial it in slowly as both the sensor and engine temperatures approach working temp - ie. they run open loop for 20-30 seconds when the cars started, HOWEVER they do use the engine temp sensor for feedback and adjustment of fuelling

* Give or take a few other variables such as engine temp etc, the VR-4 ECUs will run closed loop until either the throttle is depressed beyond 50% or the engine load goes above 50% (whichever comes first), at which point it then switches to open loop

* A narrowband oxygen sensor has a sharp swing between 0.9 volts (+/- 0.1v) for about 14.5:1 and under, and about 0.1 volt (+/- 0.1v) for 14.9:1 and over. The ECU tries to meet stoich by repeatedly running rich and lean, crossing over that "line" on purpose to hunt for 14.7.

With the above bullet point in mind, logically one of three scenarios is happening:

1. Either the ECU is running open loop and the cell for that RPM vs LOAD value is out and needs adjusting (or like mentioned previously, injector scaling is out, however this is unlikely if you're running a stock ECU)- this is what I also consider, one thing is, that it was ok for a while, well since got it flash on japfest2, it is possible that maps, somehow 'adjust' itself and causing all mess?
2. The narrowband output of the MTX-L is set too smoothly, resulting in slower response times for fuelling (again, doesn't sound likely)- all is set as it used to be, just to be sure I reset all to 'factory settings' after last calibration yesterday.
3. If you're still using the stock narrowband for fuelling, its age could be resulting in slow reactions, making the ECU temporarily think the car is running richer than it is- as said above, im on wideband only

These are just thinking out aloud, probably wrong on a few points, take it all with a pinch of salt

THANKS

[swinks]

Its used to happen occasionally that my car run lean on light/part throttle, but since I don't use it daily, rather once a week now, this issue become more common, to this degree that it's bad most of the time now. On idle afrs are mostly nice and steady (14ish) but sometimes it start leaning out to 18ish and car trying to stall then its some kind of a 'click' and all back to normal.

To be more precise, when cruising around on light load afr go up to 16-18, I assume only in closed loop as when I put my foot down its behave as it should, ie afrs drop to 11-12s.

So far I did this

swap MAF- no change
swap bov from forge to stock- no change
recalibrate wideband- no change, well it was normal for first few miles then start leaning out, then back to normal and again and again
check all vacuum/turbo pipes, all seems to be ok

Are you running adjustable fpr?
If so it's likely it's gone bye-bye.
Had identical issue few years back when my 1st fpr refused to work.
And if you hooking up new adjustable fpr, then get vacuum directly from manifold, just by-pass solenoid.

[adaxo]

Are you running adjustable fpr?
If so it's likely it's gone bye-bye.
Had identical issue few years back when my 1st fpr refused to work.
And if you hooking up new adjustable fpr, then get vacuum directly from manifold, just by-pass solenoid.

No FPR, petrol side is untouched.

[swinks]

No FPR, petrol side is untouched.
Then fuel pressure is not stable. Fuel pump?

[TAR]

I still have this issue and mine is so regular I can repeat it on demand.

When cruising on light throttle (boost gauge showing vacuum) the AFR will be perfect fluctuating between 14.1 and 15.1. Soon as I apply a little throttle (still in vacuum) the car will lean out to anywhere between 15.8 and 16.7. If I put my foot down a little more to get to to zero vacuum zero boost AFR will return to 14.7. If I floor it, AFR goes down to between 10.1 and 12.2.

Occasionally, when starting a warm engine, the car leans out to 17 AFR and I have to go WOT for a second or two, after which it settles back to 14.7 AFR.

I have changed the TPS and reset it to factory setting.
I have changed the MAF
I have fitted a hard pipe kit with new silicon joints and murray clamps
I have fitted a Greddy intercooler
I have a Sytec FPR, set correctly
I have also tried connecting the vac line to the FPR both with and without the stock FPR solenoid connected)
I have a Walbro 255lph fuel pump
I have checked for air leaks.
I am currently running a stock manual ECU
I have an Innovate MTX-L regularly calibrated - currently replacing the stock O2 sensor (same thing happens with stock sensor in place)

I am totally convinced that this is an electrical issue but have so far not got to the bottom of it.



:sigh:

[adaxo]

Then fuel pressure is not stable. Fuel pump?

All that happens regardless of what fuel im on, lpg or petrol, if is bad it's bad on both, if is good it's good on both.

[fassi1]

One of the petrol injectors could be gone. When the resistance too high, ECU will cut the signal out on that faulty injector and AFRs go to 17-18.
You can use your lpg ECU (software) to check if that happens, it will show 0ms for this cylinder when it happens.
It will happen on petrol and lpg, lpg ECU will follow petrol ECU.
Don't you get engine management light flashing?

[adaxo]

One of the petrol injectors could be gone. When the resistance too high, ECU will cut the signal out on that faulty injector and AFRs go to 17-18.
You can use your lpg ECU (software) to check if that happens, it will show 0ms for this cylinder when it happens.
It will happen on petrol and lpg, lpg ECU will follow petrol ECU.
Don't you get engine management light flashing?

Will have a look tomorrow, actually I was plugged to lpg ecu to check how things going and all injectors runnig but iirc at this time car run fine.

[adaxo]

All injectors running ok.

[fassi1]

All injectors running ok.

Even when afr 17-18?

[adaxo]

Even when afr 17-18?

yes.

[Davezj]

interesting read adam, i am not sure what it can be, but i bit of logging tonight should shed some light on the subject, hopefully.

[swinks]

There few bit left to check:
- vacuum leak before turbo (low pressure side)
- tps vs. ips being off scale
- ecu electrical goblin

[adaxo]

Just back from Dave, and flashing back roms not help, we both cant find anything what could causing this issue, Dave may pop in later and write his observation. What I just remember now that I changed battery and clamps few weeks ago as mine old one died completely and I was driving car with completely dead/flat battery for about 15 miles, is that could make a mess?

[Davezj]

Here are the logs we did, have a look at the lastest time stamped log, there are some odd things in there that i am just not sure about.
i don't know if they are symtoms of the issue or what is causing the issue.

65184

i was looking at the last section of the log as we drove up my road quite slowly and to be honest the engine was a bit laboured as if it was striggling to stay running. the afr is showing 20+, the timing is bouncing up and down, the battery voltage is fluctuating and some other stuff in that reagion looks unstable. sorry can't remember what, i will have to look at them again.
but as i say i don't know if these are because of the high afr or these are what is making the afr lean.

the key points in the log to look for is throttle position of almost nothing, just crusing at 30 or less and the External wideband when that goes upto about 20, then switch on and off all the other logged values in turn to see if the result looks odd. some of it does. particularly when the afr drops back down to normal levels, the other logged data returns to what i would expect to be normal. battery voltage included.

i know if you are on the verge of stalling the battery voltage will drop but this seems to happen in places all along the logged graph. don't get me wrong it does not drop be much but it fluctuates which it does not do else where on the log.

but i think i maybe clutching at straws. it will need some more looking at. but that is for another day, i am off to bed, as last night was a 2.30am finish, and up at 6.00am.

[TAR]

I forgot to mention that I have a full set of reconditioned standard injectors fitted to my car. The car still runs very smoothly except when you can feel the ECU pulling the timing at very lean AFR.

:happy:

[fassi1]

Alternator???

[TAR]

Chris, is that aimed at me or Adam?

I'm sure my one is fine. What is your thinking behind that?

:happy:

[adaxo]

Alternator???

Yeah why you think it could be alternator? I got one or two spare but change them will be pita. Thanks for thoughts.

[wintertidenz]

Have you checked all the wideband wiring? I had a problem with my turbo timer corrupting the calibration of the wideband (killed power to the ECU for a split second, enough to upset the LC-1) and it would cause the car to run lean, then stupidly rich.

If you have it, it might be an idea to put the stock O2 sensor back in for testing and see how it goes.

[Davezj]

adam has got spare mtx-l O2 sensor, which could be swapped.

how about a recalibrate of the sensor, i know it has been done recently but in what conditions.
the normal way of doing it in the exhaust pipe, first thing in the morning which is a perfectly acceptable way of doing it.
however in the weather we are having at the moment the sensor will probably be covered in condensation and more so due to the LPG as it normally creates more steam in the morning. Well it did in my old LPG Jeep.
so if the ignition is turned to ON the sensor will heat up normally, then switch ignition off and back to ON to heat the sensor again, to ensure there is no condensation on the sensor. you could do this a few more times just to make sure.
Then do the normal calibration method. and see what happens.

It cost nothing to try, and it might make a difference.
the other thing to try is to disconnect the sensor and run it like that. It should run rich in what would be closed loop mode, which is how adam ran his car for a few months without knowing he was. as the narrow band emulation wire had disconnected from the loom so no O2 input to the ecu.
much better to run rich than lean.


so my plan would be,
1. try the recalibrate with the sensor warn up prior to doing the calibration. see what happens.

2. disconnect narrow band emulation wire from ecu input.

3. connect up your spare MTX-l system and do a temp connection of narrowband output to you car and see if it makes a difference with the spare gauge and sensor in the exhast pipe.

4. if sothat works , swap the O2 sensor and see if it is just that part, if that doesn't fix it swap gauge as well.

if that does not change anything then just disconnect the O2 sensor and run it rich, log it and see if it runs the same as it did before. running without O2 will not harm the car it will just run a default very rich setting as it did before.

at least you will be able to go to the RR Day all dyno pulls are done in open loop and don't use the O2 sensor output.

[fassi1]

Yeah why you think it could be alternator? I got one or two spare but change them will be pita. Thanks for thoughts.

Just thoughts.

I looked at your log and narrow signal is not right. When afr 11s (rich) narrow signal is 1.78.. Volt, when afr 20s (lean) narrow signal is 0.48.. Volt, that doesn't look right.
The narrow signal range from MTX-L is 0-1.1 Volt, with afr 20s it should be close to 0 Volt not 0.48.. Volt, the same with rich mixture no matter how rich that is it should never exceed 1.1 Volt (close to 1 Volt). Fuel trims (oxygen feedback trim STFT) dont look right at the same time great negative -16% -17% when rpm about 2500 and narrow signal about 0.5 Volt constant ( it should be oscilatting 0-1 Volt at that point in closed loop, never constant) and afr 20s, cause of narrow signal too high ECU is trying to lean out the mixture that's why stft -16% -17%
My thoughts.

[adaxo]

Just thoughts.

I looked at your log and narrow signal is not right. When afr 11s (rich) narrow signal is 1.78.. Volt, when afr 20s (lean) narrow signal is 0.48.. Volt, that doesn't look right.
The narrow signal range from MTX-L is 0-1.1 Volt, with afr 20s it should be close to 0 Volt not 0.48.. Volt, the same with rich mixture no matter how rich that is it should never exceed 1.1 Volt (close to 1 Volt). Fuel trims (oxygen feedback trim STFT) dont look right at the same time great negative -16% -17% when rpm about 2500 and narrow signal about 0.5 Volt constant ( it should be oscilatting 0-1 Volt at that point in closed loop, never constant) and afr 20s, cause of narrow signal too high ECU is trying to lean out the mixture that's why stft -16% -17%
My thoughts.

Thanks for look in to logs Davezj fassi1 , this is what catch my eye as well, just as confirmation from you, narrow my plan of attack, for today, get some sleep (if I can, as this issue drives me crazy, just b4 dyno day which I was waiting for many many months), then take narrow band emulation off and see if this make a difference, if not then I will try to reverse what I did during battery change few weeks back (fitted new clamps with some fancy voltage display, probably manufactured in China), if this not help then I may swap alternators as I think it may broke when was driven virtually without battery, since then its make some squeaky noises.

[fassi1]

Alternator voltage looks alright. I would concentrate on narrow signal, maybe swap o2 sensor for stock one and do quick log and check if it oscillates
0-1 volt at light load with nice single figure stft.

[chris_dono]

This sounds like the same thing my car's been doing recently as well, did anyone find a solution ?

[Davezj]

adam, keep us posted on what try today. and i will see if i can bob round tonight to give you a hand.
i will see if i can dig out my osciposcope to read the O2 sensor dirctly to see what is coming out of it, before the gauge does anything to the signal.

but as you have the other mtx-l kit you can put that up you exhaust pipe and smoke it, so to speek. you will have to connect the narrow band emulation signal to the spare kit to your ecu pin at the same point the in car mtx-l was spliced in. that will tell you if you mtx-l fitted in the car is working correctly, or if something has gone wrong with it.
simple test for you to do as you have the spare kit.

If the reading on the spare mtx-l kit is the same as the in car mtx-l and you get this lean out issue with the spare kit then the mtx-l in the car is reading OK and not causing or influensing the issue.

[fassi1]

I wouldn't disturb wideband signal with any external diagnostic devices Dave.
If another wideband kit reads the same afr it doesn't have to mean that both are ok, wideband signal and afr on gauge can be fine but emulated narrow signal can be wrong and it looks like that when you look at last log.

[swinks]

Narrowband sensor issue is rather result of something wrong going there. Adam said previously it happens also whilst driving condition. Ecu in that situation ignores o2 signal.
I still think that problem lay on fuel side. How exactly are lpg injectors and fuelling solved in your setup, if all signals are taken from petrol setup, then here we go...
Adam, you run stock solenoid and fpr, hence pressure and signals are fed to ecu to driven by one.

I rather think that lean condition is result of excessive unburnt fuel. In worst case scenario unburnt oil.

For starters... replace wideband (I understand that you running emulated narrowband) with stock narrowband - I can get one to Area 52, if symptoms dissapear then you have answer: Innovate sucks ;)

[fassi1]

ECU is not ignoring O2 sensor when in closed loop with oxygen feedback stft -16% been calculated, at that point afr 20 and narrow signal 0.54.. Volt

[swinks]

ECU is not ignoring O2 sensor when in closed loop with oxygen feedback stft -16% been calculated, at that point afr 20 and narrow signal 0.54.. Volt
I'm talking about open loop situation. The same happens. Read again what I said ;)
Afr bouncing from ultra rich to ultra lean and back whilst transition from closed to open loop, and each time acceleration is detected... that's not lambda IMO.
Tomorrow we will know, I'm taking stock narrowband with me :)

[adaxo]

Ok here's a small update, i start play with it around 2ish, first thing what I did was taken off lambda from exhaust and calibrate it once more step by step as said in manual, stick it back start car and here we go, been driving for about 40 miles and so far so good car running as used to run /megawoot (i love this cold damp weather /rally) evoscan logs, especially o2 readings looks much better now, hopefully this stay as it is, don't exactly know if this is sorted by taking lamda out or some dodgy connection as i disturb all ecu area to unplug sensor so may its something bad happen here, will redo all that later as its become really messy in this spot (utcomp, amp, gps, and so on)

will upload new logs later (on my notebook atm)

THANK YOU ALL FOR HELP /grouphug

[fassi1]

There u go, only closed loop was affected when oxygen feedback is monitored and never ignored by the ECU unless in open loop.
Well done Adam, enjoy cold dump weather.

[Davezj]

Glad you got it sorted adam, you shall go to the ball, i mean dyno day.

[adaxo]

Glad you got it sorted adam, you shall go to the ball, i mean dyno day.

O yeach, area 52 bring it on, aiming for 300 HP at least /lol

[Davezj]

me too. i am sure it will be doable.

[TAR]

Glad you got it sorted Adam. I wish my issue was as easy to diagnose.

I have tried with both stock narrowband sensor, a replacement narrowband sensor and (currently) the narrowband emulation from the wideband.

I hope to get some Evoscan logs soon, I may post them up if I can't see what's going on.

:happy:

[wintertidenz]

So it was the wideband then?

I've found that even leaving the car sitting overnight doesn't give enough time to allow the sensor to calibrate in free air. As I mentioned before, I've had issues with the Innovate having massive fits with even momentary drops in voltage. They are overly sensitive to grounds and voltage, not sure why.
Another alternative you can do for the MTX-L is use a separate ground, and a permanent 12v fused feed from the battery to a relay that gets triggered by ignition. This should give it the cleanest possible voltage and prevent issues.

[Davezj]

i think there might be a update to this thread soon.

[exevoowner]

Maybe but not 400bhp

[fassi1]

So it was the wideband then?

I've found that even leaving the car sitting overnight doesn't give enough time to allow the sensor to calibrate in free air. As I mentioned before, I've had issues with the Innovate having massive fits with even momentary drops in voltage. They are overly sensitive to grounds and voltage, not sure why.
Another alternative you can do for the MTX-L is use a separate ground, and a permanent 12v fused feed from the battery to a relay that gets triggered by ignition. This should give it the cleanest possible voltage and prevent issues.
There is wire under the dash which does exactly that 12V after ignition,
Using it for mtxl and lpg system, never had problems.

[wintertidenz]

I'm meaning using a separate feed from the battery itself, all fused - running to a relay that allows the current to flow when ignition is on. This way you can avoid drain from any other devices on the circuit.

[adaxo]

My joy was slightly premature as issue go back straight next day (dyno day) so b4 we went I cut out narrow band emulation and car run 'normal' little bit richer and sluggish on WOT, but not stupidly lean on light loads, at least this narrow my future test to lambda sensor/innovate gauge/emulation.

[disco-ian]

I'm getting lean readings on light throttle and more so light throttle after fuel cut when the engine is warm. If its warm enough tomorrow morning before work I will get the car jacked up take the lamba out and do a recal on it. I'll let you know how I get on.

Sent from my Galaxy sIII

Ian

[swinks]

For future, please get my advice from dd day and run 2 sensors, one stock narrowband and 2nd wideband. It's quick and not expensive job to weld o2 boss on top od de-cat. And you make your ecu very happy :)

[wintertidenz]

I have to agree with Tomasz here - a good narrowband with a wideband in place to monitor seems to be the way to go, because if the calibration ends up going out on the wideband at least you know the car is still running correctly.

Or alternatively get another kind of wideband - the AEM/PLX ones are good and aren't so sensitive to wiring. Not sure if they do narrowband emulation though.