My 1995 Mk3 1.8i Golf (Engine code ADZ) is failing it's exhaust emissions at high idle.
The print out from the test centre gives the following information:
RESULTS
Engine oil temperature 69 C
Low Idle CO 0.14 vol% Pass
(880rpm) HC 30.00ppm Pass
High Idle Lambda 1.01 Pass
(2920rpm) CO 0.38 vol% Fail (above 0.3% )
HC 18.00ppm Pass
The catalytic convertor was replaced last year so is hopefully not the cause of the problem as it was very expensive to replace. I have also replaced the air filter and the coolant temperature sensor. A local mechanic has suggested that I put an injector cleaner into the fuel and let it do it's stuff before I take it in for a retest.
He has also told me that there is no adjustment of the idle settings on the car.
If anybody has any other suggestions / ideas please fire away.
Thanks,
S
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Run through tank of fuel with injector cleaner in it Get it warm and give it a good thrashing on a motorway, runnit it near the red line for 5 or 10 minutes.
Also the car wasnt hot when it was tested. it looks to be at least 20c down on running temperature.
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If it is a build up of carbon which injector cleaner do you recommend ???
My local mechanic has suggested a STP Service pack . Which is a 2 bottle kit.
The first botte is the injector cleaner, to be run through in the first tank of fuel.
The second bottle is a petrol treatment which is to be added to the second tank.
Thanks for the quick reply.
S.
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S,
Whay are you asking if the idle can be adjusted? Is it too high? Or did you mean can the CO be adjusted? (In either case, no.)
If the car is mainly used for short runs, then the chances are the CAT will just be sooted up. (I take the the new CAT was OE?)
Dont worry about a fuel cleaner. Just fill up with a premium grade fuel. (Ie NOT the "economy brand") and take the car for a drive at speed for at least 1/2 hour@ 60mph min. If the car is manual, then keep it in fourth not fith as you want to keep the revs up. Then drive the car briskly through the rev range a few times. Make sure the car is fully hot for the retest, and ensure it is over 80 deg! (That temp was too cold, but should not have caused the fail.) Ask if the emmisions can be checked BEFORE the car is registered for the retest as the PC will only give you one try.
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Sorry I meant CO adjustment and not idle.
From the answers so far, I take it most people agree with my mechanic's diagnosis of carbon build up. Does anybody have any other ideas of possible causes of high CO at high idle.
For info. the cat was a replacement unit.
When it comes to the retest I will definitely make sure that the engine is piping hot !
S.
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If anybody has any further ideas ? , solutions to this problem ? or personal experience of fixing high emissions at high idle with a fuel injector cleaner. I would love to hear from them.
Many thanks,
S.
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Ladies and Gents,
I have got a retest booked for next Thursday 11th Feb.
So if anybody has any further solutions I would love to hear from them, before I contribute again to the government coffers !
My plan is to run the tank down to about a quarter full. Then put in a fuel line cleaner on the morning of the test and as previously suggested give the car a "really good thrash" for about 30 mins. before I put it in for the test .
S.
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Passed !
Thank-you all who replied to my thread.
My plan ( see above ) worked.
S.
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good to know, you know what to do the day before the next MOT now!
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