RedWS6 00

My car failed the emmisions test. CO2 and the other gas was like 10times under the limit, they said the lambda was off, probably caused by old cats. So I thought I'd get some new cats. Thought I'd go the whole hog and get Dynotech LT's, High flow cats and Y-pipe. Went back for emmisions again today, and still lambda is off. Havn't changed the O2's, the cats are new, like 40miles on them.
I can see my O2's occilatiing very nicely, pretty fast apart from tick over, but I guess thats normal. I'm wondering if the O2's are dirty can they be occilating at 14.2 for example? Got emmisions retest on Saturday. I'm in england so cant get new O2's before then. Can they be cleaned? is this my problem?

Picture of O2's working attached.

brad8266

iTrader: (23)

The pic isnt that clear but it looks like your LTFT is like -14, which is too rich. May need to fix your tune. Hopefully someone else chimes in that is a little better than I am.

jimmyblue

iTrader: (11)

They look pretty well behaved, the O2s. Cats have
nothing to do with lambda, though. That's just an
expression of mixture going in. Cats have to deal with
the residual products. The O2 switchpoint is deisgned
to be 14.7 for gasoline but it really works off oxygen
content. Anything that introduces air into the exhaust
will fool the system into thinking it's lean and make the
cylinder charge rich to compensate. But the trims indicate
the opposite problem, naturally rich and being pulled back
to lean by the trims. Why would fuel be delivered long?
Either an overreported airflow, high fuel pressure or some
error in modeling the injectors, those would be the top 3.
I'd verify the IFT table against what you can calculate up
for the 42#ers and measured fuel pressure, be sure you
know what the Walbro is delivering now. Then have to
check into how you deleted EGR, did that get properly
related to the speed density tune (low throttle VE sure
will change)? Maybe you should post the VE table you
have now. Ported MAF, oh joy. That's a science project
that you might want to save until you're convinced the
rest is straightened up. If it's even in the picture
anymore?

The AIR being gone, might get you some cold start emissions
trouble, it's meant to help the cats light off quick. If you
have the cats, why not keep AIR?

RedWS6 00

Yep they are -14 at that point, I need to to an SD tune. But if the O2's are occilating that should mean it pretty spot on to 14.7 AFR I beleive, no matter what the fuel trims say, the fuel trims have done their adjustment to get the AFR spot on. I could be wrong. I probsably am, I hope I am, this could mean if I do an SD tune I could get it through the emmisions. Saves me buying O2's, as it appears they are working.

horist

as mentioned, the O2s measure lambda not necessarily 14.7:1 ... your sensors look fine, but looks like you're running rich (LTRIMs are pulling fuel)...

I'm wondering how they're measuring lambda.... maybe they meant hydrocarbons? (excessive hydrocarbons come from running too rich, NOx will be high if too lean)

Is this emissions in the UK? Do they only do sniffer or do they also do OBDII?

RedWS6 00

Thanks Jummy, you spend a lot of time explaining things, its much appreciated.

The Cats are only on there for the emmitions test, the day after this test the cats are coming off and the straight throgh pope will be fitted, in this pipe is my wideband sensor.

Made sure my new LT headers didn't have a port for AIR system, it looks a little nicer and I beleved it wasn't needed if I was removing the cats. Also no port for EGR on the new headers, and the LSX intake manifold I left the port plugged.

EGR was disabled by a few things...
Engine / Airflow / Dynamic Airflow / EGR Test Disable = 0.0
Engine / EGR Enabmes = Disabled
Engine / Diag Disable speed = 6mph
Engine / Diag Enable speed = 8mph
Engine / Spark Control / Spark Advance / EGR Correction = All cells in table zeroed out.

I mentioned ported MAF, acutally its just stock MAF with anodised MAF ends, from Thunder Racing, cant find thier part number on there website at the moment. I could take the MAF oput of the equations, in fact I think I will when I do an SD tune over the next days. Just need to avoid the cops as the car is illegal on the road at the moment with no emmisions ticket.

Injector Flow Rate:-
49.66635 49.97637 50.28640 50.53442 50.84445 51.15448 51.46450 51.71253 52.02255 52.27057 52.58060 52.89063 53.13865 53.44868 53.69670 54.00673 54.25475
Fuel rail pressure is showing about 60psi, I have an analogue guage on the fuel rails.

The headers were put on at the weekend, I dont think there is any leaks, I'll double check. If there is a leak and oxygen is getting in it would explain alot.

I do notice I get a lot of negative fuel trims under 30kpa, I guess thats the lack of EGR.

RedWS6 00

They only do a sniffer here in the UK, my CO was way low and I think it was Hydrocarbons were like 10times under the limit too. I was running HP Tuners scanning during the emmisions test, and even if I played with forcing the AFR between 13.7 to 15.7, I was changing the CO's but it didn't help me out on the lambda. The emmisions test is a case of sitting there at 2500rpm, that image I posted was during the emmisions test.

RedWS6 00

Found emmisions test from last year.

CO needs to be <0.30%vol
Car produced 0.03%vol
HC needs to be <200ppm vol
Car produced 2ppm vol
Lambda needs to be 0.970 - 1.030
Car produced 1.005

So last year is all passed.

This year my CO and HC are about the same. Lambda is 1.070 which is a fail. Which I guess it means it thinks I'm running 15.7AFR which would make you think some how air is getting into the pipes.

white2001s10

iTrader: (4)

So you fail an emissions test for passing too much fresh air out the exhaust.
That's just poetic.


I suppose new O2 sensors might solve it.
I would also check for exhaust leaks between your front O2's and the tailpipes.
Do they stick the sniffer up the pipe or does the exhaust go to a remote sensor?

RedWS6 00

On the emmisions test this year I had a corsa cat back, 2 tails pipes on eash side. It failed emmisions so they told me to change the cats so I did, in changing the cats I changeod the headers to. Still faild the test. The stick the sniffer up one of the pipes, I am wondering if they are not putting it up far enougth, as the corsa is one pipe to 2 on one side, I guess if they cant get it up far enough it too near fresh air. I havn't seen how far they managed to get it up, of course with the stock system there is nothing to stop you getting it up further.

I guess its possible air if coming in after the front O2 sensors. I'll check the exhaust for leaks.

RedWS6 00

I know the front O2's control all the fuel balancing, do the rear O2's have any effect, I beleive they only let you know if the cats are working. I'm just wondering as I havn't logged the rear O2's for some time, if they are malfunctioning could they make me fail the emmisions?
I guess the front O2's say it all, they beleive the fuel/air balancing is perfect...
arrgghhh, I'm going round in circles. I bet after all this they have a dodgy tester at the emmisions station.

Right I'm going to start to wire up my wideband. Drill some holes at lunch time to get the cable to the engine bay, and plug in the sensor tonight. I bet my sensor is better calibrated than their system. I'll plug it in place of one of the rear O2's.

jimmyblue

iTrader: (11)

Is there any chance that UK petrol has a different AFR
stoichiometry than the US 14.7:1 gasoline?

You might want to look closer at the O2 switching behavior
at the points where you are being "probed", make sure you
do not have a sleepy problem at idle ("ticking over"?) that
needs more heat kept in the tubes etc.

Not sure going to long tubes and high flow cats, will help
you relative to the original setup.

RedWS6 00

Hopefully the fuel is the same stuff. Unleaded, graded at 95 RON, or 97 RON, had a tank of 95RON during the test. The picture I uploaded in the first post was during the test, 2500 - 3000 rpm, and the O2's were switching pretty good. Have deen under the car looking for leaks, cant see any up front, will check the back end shortly. The emmisions test didn't want to do a tickover test, only mid revs.

I have removed one of the rear O2's now and put in place the wideband sensor so I can see it on the dash. First time I have used this sensor, I know I have put it after the cat and not ment to, but I'm hoping it should give me an idea of the AFR.

I have found another testing station who get road leagal dragsters through the emmisions test, so I do have a fall back plan, it will cost, and they dont know too much about my car, usually older american cars they deal with.

white2001s10

iTrader: (4)

I have a feeling your system is working perfectly and they just didn't put their sensor far enough up the pipe.

RedWS6 00

Thats what I think too, as last year I had standard exhaust and it pasted, this year I have a corsa cat back, and it failed. O2's doing the same as last year. Darn garage costing me money, I dind't see how far up they put the probe, but its about 2ft long, and seems quite rigid, I dont think they put it in there far enougth.

GuitsBoy

iTrader: (4)

I recently had a NB o2 sensor that was getting lazy. It was enough to make the LTFT's -8 to -10 on one side. Wideband says it was switching at 15.3 or so. Ive since switched sensors and its back to 14.7.