It just failed its MOT!!!

[V6 JIM]

Hi Guys,

My 3R went in for its service last week and I forgot to get the MOT done at the same time. The car came out fine running smoothly but just put it in for its MOT and it failed on the emissions. I looked at the reading when he was doing it and it was over 4 which he said is way too high it should be under 2.0.
Any advise what to do now? Do I go back to the dealer that serviced it or get someone else to have a look?

Cheers Jim

[MadMacMcMad]

Is it standard?
Does it have a Roush or ANOther aftermarket exhaust? If so are the cats in place or bypass pipes?

I have a friendly MOT station near me, who will pass mine based on tick over levels and only 1 cat fitted. Mine is not standard.

[V6 JIM]

Yes the car is standard with original exhaust. they measured it at 3000 rpm not at tick over.
How should it have been done?
Cheers Jim

[peterguk V6 KWK]

V6 JIM said:

Yes the car is standard with original exhaust. they measured it at 3000 rpm not at tick over.
How should it have been done?
Cheers Jim

Jim

Your MOT tester tested the emissions the correct way. The engine is run at 3000rpm to induce closed loop control within the ECU which allows the 02 sensors to be tested. There are a few MOT stations which will still risk bent MOTs, but i don't see the point - might as well have the car running properly.

I don't understand the units you were given... The "2" and "4". You would normally expect a %, e.g. 0.8 or 1.2. Can you enlighten?

[V6 JIM]

Looking at the report think they tested it the old way and new way. the report is the old way which says limit is 3.500% but my car reading 5.652%.
Do you think it needs a re map? I live near roush and heard there is someone that does the mapping?

Not sure what to do really?

[peterguk V6 KWK]

Old way... New way...

IIRC:

Petrol engined cars 1st August 2001 on...

Fast idle 2500-3000rpm
CO no more than 0.3%
HC no more than 200 parts per million
Lambda between 0.97 and 1.03

Normal idle 450-1500rpm
CO no more than 0.5%

Sounds like 02 sensors need checking...

Edited by peterguk V6 KWK on Saturday 18th October 19:23

[V6 JIM]

Im not very mechanically minded at the sort of things, the guy doing the MOT thought alot of himself but i dont think he was that good.

If the sensors were faulty should it have been picked up at the service the week before?

Thanks
Jim

[peterguk V6 KWK]

V6 JIM said:

Im not very mechanically minded at the sort of things, the guy doing the MOT thought alot of himself but i dont think he was that good.

If the sensors were faulty should it have been picked up at the service the week before?

Thanks
Jim

Hmmm, depends on what your garage defines as a service. We always gas test during a service, but then others may not. IMHO, any decent service should include a gas test. 5% is high... very high..

[D_G]

The test is the same for post 1995 cars - Fast idle test is 2500-3000RPM and the CO,HC & lambda readings are tested, then the idle test is CO & HC. Your readings of over 5% are very high, as Pete says check the Lambda sensors as if they do not output a signal the computer interprets that as a lean mixture and puts in more fuel.
To test them you need a multimeter, earth the black probe and push the red probe into the black wire connector on the sensor. Warm up the engine, set the multimeter to show DC volts. You should see a fluctuation between approx 0 and 1 volt, if you blip the throttle or hold it steady it should fluctuate, if it stays at 0 volt it's dead.

Hope that helps

Dave

[V6 JIM]

Thanks for all your help but this is a bit over my head. Everything else was fine on the MOT just confused why high emissions were not picked up earlier. Will phone the garage Monday morning as it was a well known garage and was not cheap to service. I've only driven about 50 miles since picking it up! Is it still ok to drive until its sorted? (I'm guessing not) I'll keep in mind all the things you said when i speak to them.
Cheers again
Jim

[JLSELAN]

Driving the car should be no problem at all since running a bit rich for a short time should not result in any engine issues.
Depending on the age and/or miles on the car there is a possibility that the CATS are not doing their job, but as others have said, the lambda sensor is the first thing to check, and your original servicing garage should be doing that for you.

[D_G]

Hopefully your garage can check the lambdas OK, it's much better to have it rich than lean so driving should be OK. It's not a catalyst issue as they can only remove about 1% as measured at the tailpipe. Your 5% plus readings are much more than that.
Your MPG should improve no end when fixed too

Dave

[NobleGuy]

V6 JIM said:

...it was a well known garage and was not cheap to service...

Sounds familiar.

[V6 JIM]

Sorry if im being a bit stupid but the Lambda sensor is the one after the turbo which is at the back end of the car before the cat? it is a white and black wire? I need to put the red probe into the black wire.
I just want to make sure as my mate has a multimeter so will give it a go myself and hope for the best
Cheers

[V6 JIM]

done a test on the Lambda sensor it was about 0.2 on idle and went to about 0.8 ish when i blipped the throttle so that seems to be ok as it didnt read 0.
Cheers

[Jim O.]

V6 JIM said:

done a test on the Lambda sensor it was about 0.2 on idle and went to about 0.8 ish when i blipped the throttle so that seems to be ok as it didnt read 0.
Cheers

That just shows that the lambda sensor isn't dead - it could still be faulty. The output of the lambda sensor is basically a square wave, varying between 0.8v and 0.2v, switching about once per second. With age, the lambda sensor will become "sluggish", changing back and forth slower and slower. Best way to test the sensor is to use a scope, so that you can examine the waveform coming from the sensor. If you don't have a scope, the next best way is the use the diagnostic software to see the output from the sensor. Or, you can watch the voltages on your multimeter - just make sure that the sensor keeps switching back and forth about once per second.

[V6 JIM]

Thanks for all your help guys, car is going back to the garage for them to have a look at it.
Cheers Jim

[V6 JIM]

They have found the problem, its the ECU. they said two options. get the one I have repaired which will take 4/5 weeks as this gets sent off to Noble or buy a new one.
Does anyone have any other ideas?

Im still not sure how this was not picked up in the service?

Cheers

Jim

[GTO400]

James,
YHM

[Adrian W]

V6 JIM said:

They have found the problem, its the ECU. they said two options. get the one I have repaired which will take 4/5 weeks as this gets sent off to Noble or buy a new one.
Does anyone have any other ideas?

Im still not sure how this was not picked up in the service?

Cheers

Jim

Email Yellowshed off of his profile