Emissions Test Failure
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Emissions Test Failure
After initially failing my emissions test the garage adjusted the fuel mixture and it has now passed. The problem is the car is now hesitating badly as where before they adjusted the CO% it was running great.
My question is: Is it hesitating because I'm running too lean or too rich? My guess is I'm running too lean but I have noticed that it now takes me 3 litres of gas to get to work where as before the adjustment it was taking me 2.4 litres of gas to get to work.
So I am now using more gas but my CO% is almost zero.
86 5000 QT
My question is: Is it hesitating because I'm running too lean or too rich? My guess is I'm running too lean but I have noticed that it now takes me 3 litres of gas to get to work where as before the adjustment it was taking me 2.4 litres of gas to get to work.
So I am now using more gas but my CO% is almost zero.
86 5000 QT
AudiWorld Senior Member
Joined: Dec 2000
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In pursuit of happy emissions (a once upon a time tale)...
Once upon a time there was this lunatic who collected old Audis. One time this lunatic found a non running '87 TQW and trailered it home 800 miles behind an old 6 cylinder Ford pickup.
When he got it home, he discovered that (just like the previous owner said) the car would start, but not idle - it would stumble and die. He found vaccuum leaks everywhere, and once he cured them the car would idle just fine.
Unfortunately, the PO had apparently richened the fuel injection mixture richness to compensate for the lean condition caused by the vaccuum leaks. So when emissions time came around, the car failed miserably, since the mixture was set too rich.
Once the car was taken to his favorite independent Audi shop (Autobahn Performance in Atlanta GA), Martin the Magician Mechanic put the HC sniffer on the car, then turned the basic richness down to where it should have been, and the car passed with flying colors on the re-test.
So make sure you don't have any air/vaccuum leaks, and have your mechanic put the emissions sniffer up the old tailpipe and adjust the mixture accordingly. Do not let him set it by ear.
If this is done, you should live happily ever after (and pass emissions).
HTH!
-Steve Jensen
(whose career in writing fairy tales has been a dismal flop)
87 5kcstq
When he got it home, he discovered that (just like the previous owner said) the car would start, but not idle - it would stumble and die. He found vaccuum leaks everywhere, and once he cured them the car would idle just fine.
Unfortunately, the PO had apparently richened the fuel injection mixture richness to compensate for the lean condition caused by the vaccuum leaks. So when emissions time came around, the car failed miserably, since the mixture was set too rich.
Once the car was taken to his favorite independent Audi shop (Autobahn Performance in Atlanta GA), Martin the Magician Mechanic put the HC sniffer on the car, then turned the basic richness down to where it should have been, and the car passed with flying colors on the re-test.
So make sure you don't have any air/vaccuum leaks, and have your mechanic put the emissions sniffer up the old tailpipe and adjust the mixture accordingly. Do not let him set it by ear.
If this is done, you should live happily ever after (and pass emissions).
HTH!
-Steve Jensen
(whose career in writing fairy tales has been a dismal flop)
87 5kcstq
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Joined: May 2000
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Re: In pursuit of happy emissions (a once upon a time tale)...
Make sure there are no vacuum leaks??? Easier said than done. There are plastic tubes buried where no man can ever get to them. And there's only about 700 different areas where you can have a leak.
Anyways I ended up tweaking it myself and all is well.
Anyways I ended up tweaking it myself and all is well.
AudiWorld Senior Member
Joined: Dec 2000
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Here are the top offenders for the Vaccuum Leak of the Month award...
In no specific order (this is for the MC turbo engined cars):
1. Michelin Man hose
2. Three way hose on top of the valve cover
3. Crankcase breather hose from the the crankcase up to the three way hose
4. Valve cover gasket
5. Idle adjustment screw on throttle body
6. Clamp on the airboot on top of fuel inj. metering head.
7. Turbo to intercooler hose
8. Blown intercooler end caps on intercooler
That's just for starters, gimme a few minutes...
-Steve Jensen
87 5kcstq
1. Michelin Man hose
2. Three way hose on top of the valve cover
3. Crankcase breather hose from the the crankcase up to the three way hose
4. Valve cover gasket
5. Idle adjustment screw on throttle body
6. Clamp on the airboot on top of fuel inj. metering head.
7. Turbo to intercooler hose
8. Blown intercooler end caps on intercooler
That's just for starters, gimme a few minutes...
-Steve Jensen
87 5kcstq
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