High CO emissions
Discussion
I have a problem with CO emission which sounds like it might get expensive. All emissions are ok at tickover, but at fast idle (2500 rpm) the CO rises to 1.6% / 1.7% (MOT limit is 0.3%) HC varies between 64ppm and 164 ppm on first and second fast idle test (both pass MOT). Lambda is around 0.95 (pass).
Garage has checked all sorts, including replacing Lambda sensors (no difference - sent back). Now think it might be ECU-arghhhh. Anyone know if ECU can be tested easily? Suspect Mark Adams may have suitable diagnostic kit?
Any suggestions pls
Garage has checked all sorts, including replacing Lambda sensors (no difference - sent back). Now think it might be ECU-arghhhh. Anyone know if ECU can be tested easily? Suspect Mark Adams may have suitable diagnostic kit?
Any suggestions pls
What car is it?
You don't mention the running quality, so i'll assume that there is no sign of mis fire or stumbling while on the fast idle test.
Has the car ever suffered any running problems and whats the age/mileage?
The ECU is rarely the fault.
Check the ignition system is in A1 condition and that the air filter isn't being an excessive restriction.
1.7% in real terms is hardly anything and certainly not enough to produce a visible effect i.e black smoke.
If you can get the car on a datalogger, watch the switching signal from the upstream hego (lamba) sensor/s, from their switching ratio and timings you can usually assertain the condition of the catalyst itself.
I would suspect that in the absence of any hard faults the cat is a little down on efficiency.
Try a spot of redeX in the fuel to, might improve the spray quality of the injectors and ensure the fueling is optimal.
hope some of it helps.
You don't mention the running quality, so i'll assume that there is no sign of mis fire or stumbling while on the fast idle test.
Has the car ever suffered any running problems and whats the age/mileage?
The ECU is rarely the fault.
Check the ignition system is in A1 condition and that the air filter isn't being an excessive restriction.
1.7% in real terms is hardly anything and certainly not enough to produce a visible effect i.e black smoke.
If you can get the car on a datalogger, watch the switching signal from the upstream hego (lamba) sensor/s, from their switching ratio and timings you can usually assertain the condition of the catalyst itself.
I would suspect that in the absence of any hard faults the cat is a little down on efficiency.
Try a spot of redeX in the fuel to, might improve the spray quality of the injectors and ensure the fueling is optimal.
hope some of it helps.
You fail to mention what car it is ???
If everything is ok at idle, then why is it failing ???
What is the need to rev to 2500rpm ???
I assume these measurements are taken from the tailpipe. If so, then some may be a bit high. And the only thing that should cause these to be high is a faulty cat.
The cat is supposed to remove all HC emmissions, and CO emissons and convert them to CO2.
If you are taking measurements before the cat, or there is no cat fitted, then it is a different story. Either way, none of those values are high.
Te chances of the ecu being faulty are very slim.
>> Edited by stevieturbo on Wednesday 19th May 21:49
If everything is ok at idle, then why is it failing ???
What is the need to rev to 2500rpm ???
I assume these measurements are taken from the tailpipe. If so, then some may be a bit high. And the only thing that should cause these to be high is a faulty cat.
The cat is supposed to remove all HC emmissions, and CO emissons and convert them to CO2.
If you are taking measurements before the cat, or there is no cat fitted, then it is a different story. Either way, none of those values are high.
Te chances of the ecu being faulty are very slim.
>> Edited by stevieturbo on Wednesday 19th May 21:49
stevieturbo said:
What is the need to rev to 2500rpm ???
I assume these measurements are taken from the tailpipe. If so, then some may be a bit high. And the only thing that should cause these to be high is a faulty cat.
The cat is supposed to remove all HC emmissions, and CO emissons and convert them to CO2%
My guess is that it's failed the MOT quick and manual tests on the fast idle CO test.......
MOT tests are ONLY carried out at tail pipe.
oops
I came straight from Chimaera forum, so forgot to say its a 1997 4 litre Chimaera with cat, 46k miles.
It is the MOT test which revealed the fault hence fast idle at 2500 rpm and readings taken at tail pipe. Last years MOT the readings were well inside limits, so something has changed/broken. Car runs great, no smoke, pulls well etc. Similar readings on 3 different gas anaylsers too.
I came straight from Chimaera forum, so forgot to say its a 1997 4 litre Chimaera with cat, 46k miles.
It is the MOT test which revealed the fault hence fast idle at 2500 rpm and readings taken at tail pipe. Last years MOT the readings were well inside limits, so something has changed/broken. Car runs great, no smoke, pulls well etc. Similar readings on 3 different gas anaylsers too.
The MOT is slightly different here, being run by the government.
I wasnt aware there was a seperate 'fast idle' test carried out. I thought the purpose of the fast idle test was for cars that were unable to meet pass criteria at tickover.
You did say that all settings at tickover were fine, and would pass MOT.
As I say anyway, the most likely thing to cause the high readings after the cat ( ie the tailpipe ) is a dodgy cat.
I wasnt aware there was a seperate 'fast idle' test carried out. I thought the purpose of the fast idle test was for cars that were unable to meet pass criteria at tickover.
You did say that all settings at tickover were fine, and would pass MOT.
As I say anyway, the most likely thing to cause the high readings after the cat ( ie the tailpipe ) is a dodgy cat.
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