Failed on emissions - HELP!

[Jesus-Ninja]

Passed with flying colours today, except for emissions:

This is on the refusal:

"001 Exhaust emissions carbon monoxide content after 2nd fast idle excessive [7.3.2b]

002 Exhaust emissions Lambda reading after 2nd fast idle outside specified limits"

Here's the report:



Result___________________________________________D iagnosis_Limits
__________________________________________________ _______min____max
Engine_Temperature________=_Manual_Check_________P ass____60_____-

Fast_Idle_Test___________________________________F ail
Engine_Speed______________=_Manual_Check_________P ass____2500___3000
CO________________________=_1.87__________%vol___F ail____-______0.30
HC________________________=_58____________ppm____P ass____-______200
Lambda____________________=_0.962________________F ail____0.970__1.030

Second_Fast_Idle_Test____________________________F ail
Engine_Speed______________=_Manual_Check_________P ass____2500___3000
CO________________________=_1.67__________%vol___F ail____-______0.30
HC________________________=_52____________ppm____P ass____-______200
Lambda____________________=_0.962________________F ail____0.970__1.030

Natural_Idle_Test________________________________F ail
Engine_Speed______________=_Manual_Check_________P ass____450____1500
CO________________________=_1.02__________%vol___F ail____-______0.50

OVERALL_RESULT_EXHAUST_EMISSIONS_TEST____________F ail
Engine_oil_temperature_measurement_by-passed
Engine_speed_measurement_by-passed
Engine_oil_temperature_check:_Temperature_gauge_sh owed_warm_engine


So, how the heck do I fix it?

Car has adjustable regulator and walbro pump. Lambda is a wideband LC1 with the narrowband output fed into the ecu in place of the stock lambda gauge.

:(

[Nutter_John]

was the car driven like a chav who has stolen it just before the test was done ?

[Jesus-Ninja]

No, presumably getting some heat in there will help? I'm concerned about the CO as it's double the limit at natural idle and 6 times the limit at fast idle!

[Nutter_John]

From what I have seen on VR4's they really do need to be ragged hard for 20 mins to get some real good heat in the cat , straight onto the emissions test as you get there

or

Find another test center

[Jesus-Ninja]

I'm wondering if my LC1 needs calibrating....

Is there an easy way to see what lambda (if any) the ECU is getting? I assume EvoScan will tell me?

The tester said it looked like it had no lambda sensor...

[orionn2o]

Another echo of "it must be warm"... I've had figures of 35 times the legal limit when cold on MOTs before ,which has still supposedly passed when I took it to a proper garage who put some heat in!

[Confused]

I ragged my car senseless before taking it for MOT - my dad STILL have to sit there at ~4K rpm for 5-10 minutes before the values dropped.

When he went to get the probe out of the exhaust, it actually burned his hand! The first time that's EVER happened to him!

They need to get STUPIDLY hot before the values will come into line - but they will come into line. The cat is quite a way back, so the gasses cool quite a lot.

[Eurospec]

I think you guys are on it. I see two issues there. Firstly, yes the cat has to be hot, but even if it was Nicks car still wouldnt have passed.

the lambda is .962 which is a reasonable afr of 14.1, but its still too rich for an MOT. Chemically perfect combustion (14.7) will generate the lowest CO technically too.

Nicks point about calibrating the Lc is bang on i think. The fact that both tests show exactly the same lamda value right down to the 3 decimal indicates to me a calibration problem with the LC. The LC is telling the ecu that lambda is one, when it isnt. As a result its probably cycling round a value that it thinks is lambda 1.00, but actually is a bit richer than that.

see if a re-cal will bring lambda in, and CO will defo drop. If you can, take the sensor right out of the pipe to do the cal.

cheers,

Ben.

[Jesus-Ninja]

I think you guys are on it. I see two issues there. Firstly, yes the cat has to be hot, but even if it was Nicks car still wouldnt have passed.

the lambda is .962 which is a reasonable afr of 14.1, but its still too rich for an MOT. Chemically perfect combustion (14.7) will generate the lowest CO technically too.

Nicks point about calibrating the Lc is bang on i think. The fact that both tests show exactly the same lamda value right down to the 3 decimal indicates to me a calibration problem with the LC. The LC is telling the ecu that lambda is one, when it isnt. As a result its probably cycling round a value that it thinks is lambda 1.00, but actually is a bit richer than that.

see if a re-cal will bring lambda in, and CO will defo drop. If you can, take the sensor right out of the pipe to do the cal.

cheers,

Ben.

Hi Ben :)

I took the same logic and recalibrated the LC1 with the sensor hanging out of the exhaust. EvoScan interestingly showed a little closer to 1 than the MOT, and just inside the acceptable values, before and after calibration, although still a little rich. You would expect the value the ECU is seing to be the same before and after, because of course the ecu is running closed loop to hold a stoich mixture and it thinks that the values it is getting are correct (which they may not have been before calibration).

I also wound the fuel pressure right back, tothe point where the fuel pressure hardly rose with boost, and then with one eye on the KS-4, spanked the tits off it and then drove to the test centre in second and sat outside at 4k revs until they were ready.

Lambda was better but only on one test. CO was similiar to before.

Is it possibly a timing issue causing incomplete / inefficient burn?

I don't think you do MOTs at Eurospec, but I'm guessing you have a relationship with a test centre that you take cars to. I'd be interested in dropping it into you for you to get it on the rollers and have a look, and leave it with you to get it tested and collect a car with a ticket. Is this something you'd be able to take on?

I'm suspect the stock ECU won't give you much to play with. Is an aftermarket ECU going to give more in the way of potential for getting the mixture right across the ranges? As well as passing an MOT, I'd like to get a better cruise MPG (as it looks like I'm going to be driving to Farnborough every day!) and make sure than with a heavyu right foot, the car is getting what it needs.

As an aside, I did a couple of tests recently: A drive to portsmouth with the the EBC set to "nutter mode" and then a drive back with the car running on actuator pressure only, with a click to click fill of v-power on each run and using the odometer to get the mileage. The difference in MPG? Feck all! 22mpg in both directions - which may also hint at something being a miss with fueling. This was all the day before the MOT fiasco.

[Turbo_Steve]

TBH I'd put the factory lambda back in - I have an instinctive distrust of Innovate products. There's nothing wrong with them per-se, but they're cheap & cheerful and people DO have calibration and reliability issues.

[Eurospec]

Hi Ben :)

I took the same logic and recalibrated the LC1 with the sensor hanging out of the exhaust. EvoScan interestingly showed a little closer to 1 than the MOT, and just inside the acceptable values, before and after calibration, although still a little rich. You would expect the value the ECU is seing to be the same before and after, because of course the ecu is running closed loop to hold a stoich mixture and it thinks that the values it is getting are correct (which they may not have been before calibration).

I also wound the fuel pressure right back, tothe point where the fuel pressure hardly rose with boost, and then with one eye on the KS-4, spanked the tits off it and then drove to the test centre in second and sat outside at 4k revs until they were ready.

Lambda was better but only on one test. CO was similiar to before.

Is it possibly a timing issue causing incomplete / inefficient burn?

I don't think you do MOTs at Eurospec, but I'm guessing you have a relationship with a test centre that you take cars to. I'd be interested in dropping it into you for you to get it on the rollers and have a look, and leave it with you to get it tested and collect a car with a ticket. Is this something you'd be able to take on?

I'm suspect the stock ECU won't give you much to play with. Is an aftermarket ECU going to give more in the way of potential for getting the mixture right across the ranges? As well as passing an MOT, I'd like to get a better cruise MPG (as it looks like I'm going to be driving to Farnborough every day!) and make sure than with a heavyu right foot, the car is getting what it needs.

As an aside, I did a couple of tests recently: A drive to portsmouth with the the EBC set to "nutter mode" and then a drive back with the car running on actuator pressure only, with a click to click fill of v-power on each run and using the odometer to get the mileage. The difference in MPG? Feck all! 22mpg in both directions - which may also hint at something being a miss with fueling. This was all the day before the MOT fiasco.

Hi Nick,

Yeah we do have an MOT place we use, but they are bang on the buttons- no VR4 in the bay but emissions pipe up a fiesta type stuff.

If lamda is in range on the test, and its still failing CO, then it could be the cat itself. They do fail. We have a Galant MOT cat here though!

There is little you can do with a stock car to try and alter the fueling other than adjust what tuneable bits you have, but even then you will only impact afr. Leaning it out if it is too rich will help but it flattens out at 14.7 afr and although you do get a drop in Co by going leaner is very small compared to the drop from say 13.5 to 14.

Have a look at this:-

uploaded/2298/1263646058.gif

And you get the idea.

Given the bits you have, the best way to lean out the afr to hopefully drop the co enough to get through emissions is:-

Disconnect the O2 sensor from the car, forcing it to the closed loop fuel map, and stopping it trying to correct. Then reduce the fuel pressure to enable a leaner mixture without the ecu reacting. If you still cant get the CO down low enough with the lamda at the lean end of the range, then go for a cat.

Galants can sometimes be evil to get through emmisions to be fair.

uploaded/2298/1263646025.jpg


Cheers,

Ben.

[Turbo_Steve]

Didn't think we needed a cat to pass MOT?

And I was under the impression (possibly incorrectly) that the Cat only really helped with HCL and a little bit with the NOx?

[peter thomson]

Didn't think we needed a cat to pass MOT?

from VOSA Steve

For Vehicles first used between 01/08/1995 and 31/08/2002:
If there is an exact match to the vehicle's engine code/model no. etc in
the gas analyser database or the In-Service Emissions Book, then it will
have to undergo a CAT test to the manufacturer's specific limits ( as
supplied by them).

If there is no match, it will need a CAT test default limits. The CAT
default limits to be used are:
Normal Idle- max CO<= 0.5% Min/Max RPM= 450/1500
Fast Idle - max CO= <0.3% Max HC limit <=200ppm Min/.Max Lambda
= 0.97/1.03 Min/Max RPM=2500/3000


The garage should input the name /details of the vehicle taken from the
vehicle itself.

I hope this information has assisted you with your enquiry, but if you have
any further questions please do not hesitate to contact us again.

Kind Regards
Ian Byrne

[Turbo_Steve]

Thanks Peter - and the VR4 isn't listed, is it?

I only mention it as the 300 went from four cats to two and passed with flying colours (especially considering it was the BIG ones I'd removed). And that was a UK car, and listed!

The Evo will pass without a cat at all, just on mapping.
The Scooby passed without a cat too, on the factory ECU. It was a UK car, and needed to be as hot as hell, but it'd go through on the listed limits.

[peter thomson]

No it isn't listed Steve

[Jesus-Ninja]

Yeah we do have an MOT place we use, but they are bang on the buttons- no VR4 in the bay but emissions pipe up a fiesta type stuff.

Cheers for the info, Ben. The graph is really useful.

Yeah, I wan't suggesting for a minute that you'd get a dodgy one done on it, more that you'd have the kit to be able to try different things and test the effects to get all the levels right - eg cat, fuelling, lambda etc. And then, confident that you had it nailed, take it down for a real test at a station where they might appreciate the need to get things really toasty.

I'm kind of limited in that whilst I can try lots of different things, ultimately the only way I'll see whether it has worked is a trip to the tester and with only one retest for free, it could get quite expensive and I may never get it right and spend a long time trying.

RE the stock ECU - maybe I'm just trying to find an excuse to make the move (and convince the missus that it's important too ;) ), but the motorway cruise economy I'm getting is pretty poor now (22mpg), where as I was getting 25mpg combined motorway cruise, town drive and occasional thrash on my private race track. Currently the difference between what I get paid in milage and what the fuel will cost me will add up to about 160 quid a month, so over a year that's going to add up. What scope is there for an ECU witha map that I can use to lean things out for cruise, but give me the power on demand / WOT?

So, I suppose the question is: how much to go motec with MAP, set it up, get me through my MOT and save me some pennies on the motorway slog?

[Jesus-Ninja]

If there is no match, it will need a CAT test default limits. The CAT
default limits to be used are:
Normal Idle- max CO<= 0.5% Min/Max RPM= 450/1500
Fast Idle - max CO= <0.3% Max HC limit <=200ppm Min/.Max Lambda
= 0.97/1.03 Min/Max RPM=2500/3000


the VR4 isn't listed, is it?


No it isn't listed Steve

OK, so if I understand it, then mine was certainly tested with the right values?

[Turbo_Steve]

Seriously: put the factory lambda back in.
I'd bet you things improve.

[Confused]

Yeah, Nick, yours has been tested with the right values.

It's only really a pre-95 car that can get away with the higher values if it's not listed, such as Steve's 300ZX (I'm assuming here that Steve's 300ZX was an July 1995 or earlier car)

[Jesus-Ninja]

You may be right, Steve, but I'm kind of out of time. The ticket runs out at the end of the week, and I now have no time to go back and forth between the test centre trying things that may or may not work. I need the car available, and the times I can get to the centre are limited.

If I had my own kit for testing all the emissions it would be a different story, but I'm out of time now. What I need is to give it to someone and say "take this and when I come back for it it will have an MOT and I will have a bill"

[Turbo_Steve]

Then I'd stick the sensor in right now, so you know it's good and eliminate one possibility.

[Jesus-Ninja]

Then I'd stick the sensor in right now, so you know it's good and eliminate one possibility.

Well, I hear what you're saying, but I could do that, then go for anotehr test, which will cost me 15 quid and more importantly my time trecking tghere and back as well as changing that, and still fail, and then try something else, and then fail again.

Like I say, if I had something to test the emissions properly, then I could go there more confident, but TBH it's just guess work without and I simply can't be arsed with running backward and forward. I work Monday to Friday, so I could only do it on a Saturday, that's a lot of weekends titting around with it when I could give it to someone else and have it back in a couple of days.

[Eurospec]

Thats cool Nick, i didnt think thats what you were asking- we do get asked quite a bit though. I did 3 second hand cats on an evo before christmas before i got a good one!

Motec is not cheap! I can price one for you, but often the price of the box begins with a 2!

Remind me, your car is auto right, but is it pfl or post?

Cheers,

Ben.

[Jesus-Ninja]

Manual PFL.

What sort of mileage am I likely to get from a decent map for motorway cruising?

[Nick Mann]

Nick - I can get get 27 mpg at 75 mph now, and I'm sure there is more to be had. I still sometimes see AFRs of about 12.5 on slight inclines. Mostly now, my AFR's are 14.7 at legal motorway speeds. I udnerstand that it is possible to lean this out even more, but TBH, I don't do enough mileage in the car to worry about that. When I had a strange issue last year after wiring in a boost solenoid, the AFRs were leaning out on cruise. The car was fine even on AFRs of 17. In the 18s it finally started coughing!

Potentially you have a lot of savings to make there, in my opinion. But how much of it is the issue that is hindering your MOT pass, I couldn't say.

[Gowf]

Didn't think we needed a cat to pass MOT?

And I was under the impression (possibly incorrectly) that the Cat only really helped with HCL and a little bit with the NOx?


Not wholly incorrect steve, but it does all depend on the type of cat that it is (two way or three way), as there are a few.

Only recently have NOx emissions been a tested issue for cars, and its value is not a problem for us at all. The problem mainly comes from lean burn engines and diesels.

I could bore you all night with this, as I have done a fair bit of work into it and the potential of using plasma to solve emission problems (ask Matt, he had the job of proof reading all 20000 words), but i wont.

But in essence it would deal with all three to some respect

[Jesus-Ninja]

Nick - I can get get 27 mpg at 75 mph now, and I'm sure there is more to be had. I still sometimes see AFRs of about 12.5 on slight inclines. Mostly now, my AFR's are 14.7 at legal motorway speeds. I udnerstand that it is possible to lean this out even more, but TBH, I don't do enough mileage in the car to worry about that. When I had a strange issue last year after wiring in a boost solenoid, the AFRs were leaning out on cruise. The car was fine even on AFRs of 17. In the 18s it finally started coughing!

Potentially you have a lot of savings to make there, in my opinion. But how much of it is the issue that is hindering your MOT pass, I couldn't say.

Cheers, Nick. Some good info. What ECU are you running?

[Jesus-Ninja]

OK, old sensor back in, and a quick run with evo scan, tinkering along the way.

Let's get one thing straight - lower voltaqe under O2 in evoscan is richer, yes? Having gone back to the stocker, the voltage has gone down - so even richer? Weird

EDIT: OK, had a think again, and of course the report from the test centre is using 1 as stoich and anything below that is rich, any thing above is lean. EvoScan is reporting the sensor voltage, which is lower for leaner and higher for richer. So, what the ECU was seeing with the LC1 connected was richer than what it was seeing with the stock sensor connected.

So, does this mean that with the stock sensor connected and showing a leaner than the LC1, the ECU would have been compensating more for the LC1's signal by dumping less fuel in to bring the mixture down? ie because the stock sensor is telling the Ecu it's leaner than the LC1 was, the ACTUAL mixture will be richer with the stock item?

[Jesus-Ninja]

Disconnect the O2 sensor from the car, forcing it to the closed loop fuel map, and stopping it trying to correct. Then reduce the fuel pressure to enable a leaner mixture without the ecu reacting. If you still cant get the CO down low enough with the lamda at the lean end of the range, then go for a cat.


That is probably the last thing I'll try then, before throwing in the towel!

I'm thinking that I'll put the LC1 back in and do a visual check on the gauge on the dash at 2.5k revs. I'll then disconnect the feed to the ECU but leave the LC1 connected up and then do another 2.5k idle test and visually check the gauge again to see if the values lean out at all when the ECU is getting no lambda. I'll then try winding the fuel pressure back to see if that makes any further difference. In fact doing it on a natural idle is probably even easier, as I can just sit there and turn the Lambda feed tot he ECU on and off and watch the gauge without worrying about revs.

I think I'm going to have one more crack at a test, if only 'cos I need the ticket to use the car, and then either way we need to have an ECU / tuning chat, Ben.

MOTs aside, something more flexible than the Stock ECU is in order, even if only to save me some dollar on the cruising mpg. There's no reason why, to me, the cruise mpg should be any higher on a tuned car than on a stock one, or even a NA for that matter, and it should only be gobbling fuel (more than usual!) on boost.

Motec units start with a 2? Well, 20 quid is a lot of money where I come from, but I think we can stretch to that... :p Seriously though, what other options are there. Been looking on your site - is the ViPEC a realistic choice?

[Dom B]

Nick, Emissions definitely looks like a lambda fault, no doubt. Normally i would say knackered sensor but in your case with the lc1 that is obviously ruining the lambda value in trying to force the ecu into submission elsewhere in the test. Can you rig the lc1 to buffer the original unadjusted values or just plug the old sensor back in for the mot?

Had very similar readings on a 1.8t golf very recently which was cured with new pre cat lambda.

As for mpg i totally agree the car should be frugal on cruise and there is no reason why it can't be. That emissions graph earlier shows a nice low emissions region at about 18:1 afr which is totally achievable with no engine mods.

ECU wise, i am going the megasquirt route. It's a bit more diy but there is so much support for it now that you are not on your own or at the local tuning centers expense getting it to work. As it is open source you have access to all the code to customise it too.

Also check out brisk lsg halo plugs. They sell them on ebay, just search halo plug. The guy is just up the road based at silverstone. I am going to have a look at trying them fairly soon. I believe they were designed in ww2 to get more power and range out of spitfires and hurricanes.

Also i was on the verge emissions wise last mot and i found that using the rear bank mivec fto plugs reduced the emissions by quite a few % and made the engine run so smoothly. They are NGK PFR7M with the offset electrode. Not recommended for the car but they have the right thread/body/electrode protrusion and from personal experience they work superbly well.
Dom

[Jesus-Ninja]

Cheers Dom - as you may have read, I have tried both now, with mixed results (that I confess I don't fully understand!) Interesting to note your comment about soldering joints on the other thread. Will go back and change what I can. Most are crimped anyway (ie the molex connectors) so it's just where I've soldered the splices.

Regarding megasquirt - I was looking at VEMS a while back for the S14. Have eitehr been used to any extent on our engines? Whilst I'm very much a "go do it yourself" kind of guy, something off the shelf, ECU wise, set up by someone experienced with the car and the ECU has certain appeal.

[Eurospec]

In a manual, bang for buck, if you want a standalone, Vipec all the way. Direct plug and play, no looms to wire in, nothing like that. To my knowledge it is the only pnp for a Vr4 out there.

for piggy back, then map2, but you still often have to do trickery to get round fuel cut (like use bigger injectors/higher fuel pressure etc).

I have used megasquirt a few times, but in honesty i am not a fan. It will be a customise the loom job and you will then need to start from scratch. I was working with one recently and i called up a guy for a bit of advice to try and solve a missfire issue i was having. Thats no problem he says, you just cut this capacitor out of the board and use a bigger one instead. I dont like that sort of stuff- although it did work!

cheers,

Ben.

[Jesus-Ninja]

Right.

Tonight I shall be trying the LC1-back-in-and-play-with-fuel-pressure-in-open-loop plan.

Also, having purchased a new serial (RS232) to usb adapter, will be trying another trick to get the LC1 to spoof a signal to the ECU telling it that it is richer than it actually is to get the ECU to trim back the fuelling when in closed loop (ie cruise and idle) to try and get some better mileage on the motorway slog.

Ben (or anyone else who knows!), when does the map move from closed to open loop - ie is it minimal engine load or WOT?

[phosty]

Jesus-Ninja I had very similar issues with my second VR4. I tried allsorts to get it throught the MOT (MAP2 timing tweaks, LC1 lean out etc) to no avail. It turned out it was merely the CAT (or rather lack of it - the casing was empty!).

Simplist way to check if the CAT is working correctly is to get one of those IR-Thermometers (see Maplin) and then check the temperature rise (the process is exothermic) across the CAT from the inlet flange to the outlet flange. With my replacement CAT I get about 25-35 degC rise (inlet about 220degC rising to 250ish). It's interesting to note that the VR4 rarely gets hot enough if just left to idle.

At least it will elliminate one potential issue.

[Jesus-Ninja]

Hmm, maybe time to invest in a sport cat? Any recommendations or experiences?

[Eurospec]

We used to say to people to get sport cats to stop the annual cat on/cat off messing, particularly on scoobies, but we are finding they are only lasting about 2-3 years, which with the price of them is just not worthwhile.

The car is in closed loop only upto say 80-100kpa and say 3500 rpm. The stock ecu prolly has a tps dimension too, but basically if you are in vac and gently pootling along it should be closed loop. I recon it is out by an 80mph cruise though.

Cheers,

Ben.

[Jesus-Ninja]

We used to say to people to get sport cats to stop the annual cat on/cat off messing, particularly on scoobies, but we are finding they are only lasting about 2-3 years, which with the price of them is just not worthwhile.

Thanks Ben - what sort of money are we talking. I figured spotrs cats ran at about £250 a pop, although I could be completely wrong. I guess the alternative is to buy a new stock one, but would guess that that's going to cost even more.

That leaves the choice to play the game with second hand ones, which as you hinted at in another post, is not always clear sailing, and without a means to test my own CO levels before, could be a lot of effort and waiting around for bits to arrive as well as wasted trips to the test centre. Basically I want to get it nailed first time, and the sport cat route seemed to be the best balance of a) assurance that it's going to be a working part, and b) the most sensible way to spend money on a new cat.

I'd probably go decat after the test anyway for use on the private track I plan to build, so the 3 years of life could be significantly more for me.

[phosty]

I ended up with a 200 cell powerflow cat for £305 fitted. Needless to say it only comes out of (dry) storage for special occaisions...

The alternative from Mitsi was just silly money and like you I didn't want the risk of a 2nd hand one.

[Nutter_John]

why not just borrow a cat from someone , I have one at the workshop that has been used last year to pass an mot with no issue

[Nick Mann]

A bit ofa lte reply - I am running a MAP2. And although I haven't used it, it does allow me to offset the narrowband emulation from the PLX for closed loop.

[Jesus-Ninja]

why not just borrow a cat from someone , I have one at the workshop that has been used last year to pass an mot with no issue

A good idea John :) Still has the potential complication of "what if it doesn't work", but then I suppose that at least there is some confidence that the thing will be in reasonable nick.

[Nutter_John]

The offer is there nick , available with a few hours notice

[Jesus-Ninja]

you just cut this capacitor out of the board and use a bigger one instead. I dont like that sort of stuff

Me neither :no: Especially on something that needs to be moderately reliable, and not constantly being tinkered with.

Currently weighing up whether to go ECU to try and get a better map (for several reasons) or just buy a £400 corsa diesel that will give me 60+mpg and just trundle the 120mile round trip every day.....

[Jesus-Ninja]

We used to say to people to get sport cats to stop the annual cat on/cat off messing, particularly on scoobies, but we are finding they are only lasting about 2-3 years, which with the price of them is just not worthwhile.

A thought on this. The data could be confounded. That is to say, look at the sort of people that are likely to buy a sport cat. Prepared to spend money on tuning, and do it properly, so probably after high power, especially as they've gone for this route, rather than the bypass / decat - ie they want the power and they have the dollar to spend and run big power. So they probably have masses of boost with buckets of over fueling on WOT and then some more on lift off as the dumpvalve bleeds off bags of air, all contaminating the cat. Possibly even ALS, dumping more fuel in.

As a direct replacement, perhaps they would last longer, but on a modified car, as with so many components, you maybe have to life them.

Just a thought........

[Turbo_Steve]

If they've spent serious dollar having it modified, it shouldn't be overfuelling. Ever.

[Jesus-Ninja]

If they've spent serious dollar having it modified, it shouldn't be overfuelling. Ever.

But that's not true, surely, Steve. Often fuel is dumped in to cool valves and piston crowns. In fact if on WOT on a standard set up, you were running a perfect stoich, there would be something very wrong. The extra fuel cannot all be combusted, as it's richer than 14.7.

[Turbo_Steve]

But that's not overfuelling, that's just running richer than stoich. As we've seen above, Stoich isn't perfect combustion: it's only chemically perfect.

It takes quite a bit more than an AFR of 10 to really start going at a cat, and TBH if it's a really fast car, you' might be seeing AFRs closer to 12. Also, don't forget that the EGTs are significantly higher at full boost, so that fuel is less likely to be condesning on the cat as the whole thing is too hot, and flowing a LOT of gas.

The stuff which kills cats is stupidly rich running into a cold exhaust with minimal gas flow to move the vapour off: hence why lots of short runs in a car kills the cat a lot quicker than continual thrappage.

[hardarse]

hi i justed failed on my emissions aswell i just have a stock cat on but i only failed on my co. my lambda and hc passed so im just wondering if you could give us some ideas of what i should be checking before i have to invest in a cat cheers lads.

[Jesus-Ninja]

OK - well here's my findings.

Disconnected the narrow band lambda signal from the ECU, to force it to run in open loop mode, and tried dropping the fuel pressure to see the effect on what the wideband gauge was showing. I was able to adjust the mixture, but unpredictably. Just when you thought "that's it", it would lean out or go richer. Of course, at idle, there is always going to be some fluctuation about a point, but the point kept moving.

Reconnected it, and using my new super RS232 cable from maplins (one that actually sodding works!), was able to adjust the voltage output for lambda 1 on the spoofed narrow band signal, and got the car to idle and cruise leaner, so that's promising.

I guess the issue now is the CO emmisions. I've chucked in some Wynns pre MOT emissions potion (although I'm cynical about it's ability to work wonders), but a known good cat could be the answer.

John - I may avail you of your offer!

[AlanDITD]

mine failed on emissions so they used a clio instead :D

[Turbo_Steve]

hardarse - take it for a thrash and get it really hot, arrive at the MOT station and tell them to shove the probe straight up it, no messing about, and it will pass.


Nick, are you saying it now looks like it's reach proper stoich? If so, it's a lot more likely to pass.

Did you setup the fuel pressure with the vacuum pipe disconnected?

[Jesus-Ninja]

Yes, steve, stoich as far as the LC1 feed into the serial port and read through evoscan. There actualy seems to be some discrepancy between the digital feed into the PC and the display on the analogue gauge on the dash (takes a voltage from the LC1), but it's easy to tinker with. If the test centra are nice, they may let me fiddle with it on the day.

How easy is it to measure you're own CO (or rather that of your own car ;) ), can you buy something to check it digitally?

[Beastlee]

Can they stop you sitting in the passenger seat of the car whilst the emissions test is done? :)

[Jesus-Ninja]

Well, when I went back to have another go, they let me do the revs. I'm sure they'd be agreeable to me having a go, changing the setting having another go. They may charge me, I suppose, but if I get my ticket....

[Jesus-Ninja]

Evo 6 cat with 20k miles on it on it's way, 24 hr delivery.

[Beastlee]

Do they fit? Worth knowing for the future.

[Jesus-Ninja]

According to the venerable Peter Thomson. I paid 40 quid for it, delivered, so even if it doesn't, I'm sure I'll get that back, and I may just hack it to make it fit :D

[hardarse]

cheers turbo-steve. if it doesnt work, if i get a sports cat do you think that will help, cause im looking at exhausts just in case.

[Turbo_Steve]

I think you should cross each bridge as it comes to it, and not rush out and buy anything you don't need.

As mentioned above, it SHOULD be possible to scrape a pass on one of these without a cat IMO.

[hardarse]

my mot runs out in 2 days so im just stressing a bit and also about 4 months ago i had the belts changed and the car was running crap, so the garage played with the little screw near the throttle cable in the engine bay, taking the revs up to about 900. but i changed them back to about 600. would that ruin the emissions.

[Turbo_Steve]

Not really. mate. It should be fine below 1000rpms and above 500rpms.

[hardarse]

cheers mate. i will have a go with the hand brake tommorrow then go book it in. and i will take for a drive to get it hot before it goes in

[Jesus-Ninja]

PASSED!!! :D

In the end, the sodding cat I bought never arrived /wall ,but changing the voltage for lambda 1 that the LC1 was putting out did the trick. Got it nice and hot and as well as dropping a whole bottle of Wynns "Pre MOT clean burn" into 1/4 tank of fuel.

The guys were really good, and did a quick "test" before doing it properly, and she flew through on the first real try.

Should save me a few pennies in fuel too. :)

[Turbo_Steve]

Glad it's back! :) Knew it'd be the LC-1 - they're perfectly good but they do need a little more attention than "fit and forget".

[Jesus-Ninja]

Well, I just went to pick up a tow bar (Nice Witter for a Galant Estate - £10!!! :D ) from Sudbury, so a nice long round trip (190 miles by my odometer) and click to click got 25.8mpg - much better than the 22mpg I was getting before the MOT lambda fiasco. Now, to see if I can squeeze some more out of it. Might be nice to get those EGT gauges in though!

[Turbo_Steve]

I would STRONLY reccomend it before you start leaning things out!

I would also ensure you have an oil pressure gauge fitted. Oil temps are also worth monitoring.

[apeman69]

I had hassle with my 1993 Celica GT-4 one year when the MOT tester was adament on doing the test for cat equipped vehicles even though the car didn't have a cat, was made/used before the cat test introduction date and also the chassis number of my car (being an import) was not listed in the tester's book.
I was convinced he was doing the wrong test, consulted another tester who agreed with me and, together, we got the original tester to revise his thinking.

My car goes in for MOT tomorrow afternoon.
Attached is a scan of the emissions test print I got from last year's MOT. At the time it had the cat on and was pretty standard.
Have I simply got a sympathetic MOT tester? Is he doing the right test? Am I a lucky b*gger?
I thought these cars were only subject to a basic emissions test.
If so then why don't people worrying about emissions failures just ask the tester beforehand which test he is going to do and question it if appropriate. If not happy then try somewhere else. Or have I got all this wrong?
I'm no eco-warrior so as long as I get an MOT I don't really care what the exhaust gasses are doing to the environment. That isn't why I bought this car and if we're being bullsh!tted at the testing station then it isn't on.

[Humpty's Revenge]

Could this possible work Steve??

http://www.wightbay.com/XCClassifieds/CPViewItem.asp?ID=1618301

[Turbo_Steve]

If that makes even 1mpg difference to your car, it'll also make you a better lover and a millionaire.

The only thing those "hydrogen splitters" make is a fabricator happy he's in work, and someone clever quite rich..

If it's that easy: why wouldn't we all be running our cars on water by now?

[Jesus-Ninja]

I would STRONLY reccomend it before you start leaning things out!

I would also ensure you have an oil pressure gauge fitted. Oil temps are also worth monitoring.

Oil temp, oil pressure and water temp all fitted :thumbsup: