Fuel Cut

[Wodjno]

I read that the EVO 4,5 and 6 can reach 1.3 (19psi)bar before fuel cut and the EVO 7 can reach 1.5 bar(22psi) .. Is there any way we can use there MAF to allow us to higher boost levels on our cars.. Granted we will have to uprate our fuel pumps /yes and Aquamist injection would probably help to.. /Hmmm amongst other things .. :rolleyes4

[psbarham]

I read that the EVO 4,5 and 6 can reach 1.3 (19psi)bar before fuel cut and the EVO 7 can reach 1.5 bar(22psi) .. Is there any way we can use here MAF to allow us to higher boost levels on our cars.. Granted we will have to uprate our fuel pumps /yes and Aquamist injection would probably help to.. /Hmmm amongst other things .. :rolleyes4
i would say not , the settings are stored in the ecu , and that only gets a reading from the afm , what you need is a different ecu or piggy back system /Hmmm

[The Vee]

HA PSB you beat me to it!! Think the ecu would be unhappy. I'd also query the injector size with that level of boost. I'd then probably worry about the pistons. Think the crowns on these may suffer.

[Wodjno]

i would say not , the settings are stored in the ecu , and that only gets a reading from the afm , what you need is a different ecu or piggy back system /Hmmm

I was thinking that this might be a problem or every Numpty with a "Broken Bumper" would be doing it. :embarasse So as long as your using and E-manage or summat like it would be possible /Hmmm But, now comes the question ?? With the E-Manage Ultimate you can do away with the MAF totally, but then you have to start inputting Hz values /help as informed by Valmes.. But if you ran 1 of the EVO MAF's would you just be able to override the OE ECU with the E-Manage and carry on regardless.. :inquisiti /pan Or would you still have to input all these Hz values.. /Hmmm

[psbarham]

I was thinking that this might be a problem or every Numpty with a "Broken Bumper" would be doing it. :embarasse So as long as your using and E-manage or summat like it would be possible /Hmmm But, now comes the question ?? With the E-Manage Ultimate you can do away with the MAF totally, but then you have to start inputting Hz values /help as informed by Valmes.. But if you ran 1 of the EVO MAF's would you just be able to override the OE ECU with the E-Manage and carry on regardless.. :inquisiti /pan Or would you still have to input all these Hz values.. /Hmmm
i don't think you would gain anything from using an evo maf , the vloume of air being drawn in is the same so all you do is use your existing maf and reprogramme the fuel map for the existing maf :inquisiti

[Wodjno]

i don't think you would gain anything from using an evo maf , the vloume of air being drawn in is the same so all you do is use your existing maf and reprogramme the fuel map for the existing maf :inquisiti

Thats what i thought :inquisiti /duh /dunce /pan /help

[Nick Mann]

The MAF and standard injectors can cope with 1.3 bar. I also have a FCD fitted, though, so don't know if that is over-riding the fuel cut.

[Wodjno]

The MAF and standard injectors can cope with 1.3 bar. I also have a FCD fitted, though, so don't know if that is over-riding the fuel cut.

Thats the reason i have never fitted an FCD as i know that it overides the ECU's limits... /yes If i were going to raise the Boost over and above the safe limits it would have to be with uprated pump for starters and a piggy to make sure the fuelling is ok ... /Hmmm

[enigma]

How many more times do I have to say that Fuel Cut is not at a specific boost!!! /grr

It works a bit like this - MAF reads how much air is coming in and lets the ECU know. The ECU goes away and has a look to see if it is above preset limits for the RPM, atmospheric pressure, and inlet temperature. If its not then thats all well and good, business as usual. If it is, it craps itself and stops sending fuel to the engine.

Now in answer to your original question - yes there are many things you can do to the MAF to make it read a lower Hz value so when the ECU goes of to check it thinks everything is hunky dory. This is what an FCD does, it is also what the emanage does, and I have no doubt the emanage ultimate does.

However once you do this the ECU sees that there is less air coming in to the engine and decides that it doesn't need as much fuel. It then LEANS everything out and thinks its really clever! In reality this could be detrimental to the life of your engine unless you can be sure that the fuelling is the correct. In a similar way it sees less air and correspondingly alters the timing, which will again need correcting.

Now back to methods to adjust the MAF - well you can use the screw on the bottom to make more air (proportioanally) go through the unmetered area of the MAF. You can remove some of the honeycomb to allow more air to pass through the unmetered area. Basically anything you can do to force more air through the unmetered area will lower the Hz value read by the ECU and hence will eliminate fuel cut. But it may well come at a price! :rolleyes4

[Wodjno]

How many more times do I have to say that Fuel Cut is not at a specific boost!!! /grr

It works a bit like this - MAF reads how much air is coming in and lets the ECU know. The ECU goes away and has a look to see if it is above preset limits for the RPM, atmospheric pressure, and inlet temperature. If its not then thats all well and good, business as usual. If it is, it craps itself and stops sending fuel to the engine.

Maybe i'm getting Boost all wrong then. /Hmmm When ever i get fuel cut, it's always when i see the needle on the boost gauge whip round to the 17psi mark /yes Which can be on a cold morning when the air is more dense or accelerating hard in tip at to lower rev range. Both of which show increased pressure in the inlet manifold as this is where the gauge takes it's reading. I have never had fuel cut in the 10 to 16psi range.So is manifold pressure not related to boost either. /help So maybe i need to go and read a little more on the science side of all this as i am having trouble understanding WTF is going on. One day i think i understand it and the next i'm back in Numpty land. /Hmmm /yes


Now in answer to your original question - yes there are many things you can do to the MAF to make it read a lower Hz value so when the ECU goes of to check it thinks everything is hunky dory. This is what an FCD does, it is also what the emanage does, and I have no doubt the emanage ultimate does.

However once you do this the ECU sees that there is less air coming in to the engine and decides that it doesn't need as much fuel. It then LEANS everything out and thinks its really clever! In reality this could be detrimental to the life of your engine unless you can be sure that the fuelling is the correct. In a similar way it sees less air and correspondingly alters the timing, which will again need correcting..

Yup all that makes sense :thumbsup:


Now back to methods to adjust the MAF - well you can use the screw on the bottom to make more air (proportioanally) go through the unmetered area of the MAF. ..
:embarasse Err.. I took mine out and lost it. /pan


You can remove some of the honeycomb to allow more air to pass through the unmetered area. Basically anything you can do to force more air through the unmetered area will lower the Hz value read by the ECU and hence will eliminate fuel cut. But it may well come at a price! :rolleyes4

I think it's time to go for another run with the LM-1 and get some more figures...

Cheers Dave :happy:

[Nick Mann]

How many more times do I have to say that Fuel Cut is not at a specific boost!!! /grr

But it is down to volume of air going in to the engine, so boost will have a dramatic effect? I agree that atmospheric conditions will also change the amount of air going in.

And Wodj, I would definitely be using that LM-1 if you are playing with the air that much and ignoring the fuel!

[Wodjno]

But it is down to volume of air going in to the engine, so boost will have a dramatic effect? I agree that atmospheric conditions will also change the amount of air going in.

And Wodj, I would definitely be using that LM-1 if you are playing with the air that much and ignoring the fuel!

That little screw has been missing for about 4 months or more now and the figures i posted of AFR's that i got with my LM-1 last week was with it missing. :embarasse

[enigma]

But it is down to volume of air going in to the engine, so boost will have a dramatic effect? I agree that atmospheric conditions will also change the amount of air going in.

Sure boost levels will play a part, but you cant simply say 'fuel cut is at xyz psi' it will vary day to day, hour to hour and more importantly car to car!

I have hit fuel cut as low as 10psi. I have also hit it at 60% throttle. Using the emanage I have trimmed it out at WOT, but need to look at doing some more tuning at part throttle to eliminate it completely.

I have noticed that the intercooler has added so much volume to the system that the turbos are almost maxxing out trying to keep the boost up. This means they are horribly inefficient above about 5300rpm and my airflow levels off - revs rise but no more air enters the engine. This perhaps explains why I am seeing peak power at about 5200rpm.

[Wodjno]

I just had a thought and this maybe where i'm going wrong.. /Hmmm And i don't mean by thinking in the first place /pan Does the AFR measure only the flow of air /Hmmm But cannot tell how dense it is ??

[enigma]

I just had a thought and this maybe where i'm going wrong.. /Hmmm And i don't mean by thinking in the first place /pan Does the AFR measure only the flow of air /Hmmm But cannot tell how dense it is ??

Please stop thinking /grr

The MAF knows how dense it is because it knows the temperature and pressure.

As we all know

PV=nRT

so

V/n=RT/P

meaning the volume of air/number of molecules=Reynolds number(constant) times the temperature/Pressure.

Its all very easy really.

/pan

[Wodjno]

I just had a thought and this maybe where i'm going wrong.. /Hmmm And i don't mean by thinking in the first place /pan Does the AFR measure only the flow of air /Hmmm But cannot tell how dense it is ??
Nah .. Had time to think .. :inquisiti It must be able to measure the density otherwise it wouldn't tell the ECU to cut the fuel on nice cold damp days.. :inquisiti

[Wodjno]

LOL .. /lol Sorry Dave .. /yes For thinking :inquisiti And also for posting my last post after you already explained.. I had written post out but not submitted as the phone rang at work and i got side tracked..
People have to question these things Dave, /yes How else do you expect to learn without asking questions.. :P
It's not as easy as just inserting a New memory card with the relevent info and reeboting :joker:

[enigma]

LOL .. /lol Sorry Dave .. /yes For thinking :inquisiti And also for posting my last post after you already explained.. I had written post out but not submitted as the phone rang at work and i got side tracked..
People have to question these things Dave, /yes How else do you expect to learn without asking questions.. :P
It's not as easy as just inserting a New memory card with the relevent info and reeboting :joker:


old dog - new tricks :p

[colVR4]

I was under the understanding that our cars over-fuelled. Does this mean that the ECU mapping is wrong for the AFR according to a specific volume of air? If this is the case, a little leaning out shouldn't be a problem should it? I realise that to do a proper job you need an e-manage or something similar that can monitor the AFR properly, but wouldn't a slight lowering of the Hz reading from the MAF reduce the risk of fuel-cut without increasing the risk of leaning out to the point of damaging the engine?

Brain hurts = lie down now!!

[Kieran]

I was under the understanding that our cars over-fuelled. Does this mean that the ECU mapping is wrong for the AFR according to a specific volume of air? If this is the case, a little leaning out shouldn't be a problem should it? I realise that to do a proper job you need an e-manage or something similar that can monitor the AFR properly, but wouldn't a slight lowering of the Hz reading from the MAF reduce the risk of fuel-cut without increasing the risk of leaning out to the point of damaging the engine?

Brain hurts = lie down now!!


That twice!! :rolleyes4

Coming next on ClubVR-4, Fuel cut or the offside rule - which is more confusing?! :embarasse

[enigma]

A graph of my airflow signal vs rpm at WOT

you can see the upper line is what the ECU would have seen if I hadn't altered it so that it now sees the bottom line. This prevents Fuel Cut AND leans things out a lot!

[valmes]

E-manage has means to get rid of fuel cut... (both blue and ultimate) if that's what you've asked.

I don't think EVOs MAF will get you anywhere... if only to complicate things...

Inputting Hz values into "Airflow output map" is just giving your ECU what it requires - Hz values at different pressures... I think keeping IAT sensor and Baro sensor input into ECU would be a good idea... or making necessary corrections in "Intake temperature map".

I will try to get it working from MAP until weekend... and will see if I have any problems at that.

or

... :smug: I think I found a much better solution that will take care of both - MAF limitation and fuel cut...

[Nick Mann]

I was under the understanding that our cars over-fuelled. Does this mean that the ECU mapping is wrong for the AFR according to a specific volume of air? If this is the case, a little leaning out shouldn't be a problem should it? I realise that to do a proper job you need an e-manage or something similar that can monitor the AFR properly, but wouldn't a slight lowering of the Hz reading from the MAF reduce the risk of fuel-cut without increasing the risk of leaning out to the point of damaging the engine?


This is all correct, I think. But the question is - How far can you lean things out before it is detrimental to your engine? I would be quite worried about blindly and deliberately leaning out. Seems a bit like walking towards the sea at the top of Beachy Head Cliffs in the middle of a cloudy night. You know you have your foot on the ground at the moment, but where will the next pace put you?!?

[Wodjno]

... :smug: I think I found a much better solution that will take care of both - MAF limitation and fuel cut...

As long as it don't involve Hz values .. /help They scare me.. /yes /pan

[Wodjno]

This is all correct, I think. But the question is - How far can you lean things out before it is detrimental to your engine? I would be quite worried about blindly and deliberately leaning out. Seems a bit like walking towards the sea at the top of Beachy Head Cliffs in the middle of a cloudy night. You know you have your foot on the ground at the moment, but where will the next pace put you?!?

LC-1 or LM-1 anyone /Hmmm

Then you can play with your little screw under the MAF reasonably safley :D ;)

[valmes]

As long as it don't involve Hz values .. /help They scare me.. /yes /pan
I does... but without your involvement in the process :drummer:


LC-1 or LM-1 anyone
Then you can play with your little screw under the MAF reasonably safley
I would need one now... how much?

[-LegnumVR4-]

I've tried an EVO4 MAF in my car, plugged it in with no error codes/engine check light coming up. If u compare the 2 they are the same, just like the earlier VR4s and the Evo's, both used the same MAF's. If someone else would like to test it out then go for it, i didn't get to drive my car with the EVO4 MAF connected to the pipe work due to it being a mates MAF.