Oh oh, engine check light on!
Thread Starter
AudiWorld Super User
Joined: Mar 2000
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Oh oh, engine check light on!
About 1 minute after starting this morning, and while the engine was still cold, the engine check light came on. I did the usual visual checks and drove my daughter to camp...and then to Sonnen Motorcars.
When they ran the diagnostics it showed that it was a problem with the air mix. When the car is cold there's a little vacuum pipe that feeds fresh air into the exhaust manifold to ensure dilution of any unburned gas particles (my explanation! lol) So, either the vacuum pipe is loose or (sometimes) the sensor wire is malfunctioning. My Service Representative says they often cut the wire and replace it with a bigger wire that can handle larger resistance.
So engine check light re-set. If it comes on again when I do a cold start it means a trip back to the dealer...and I have to leave it for the engine to get really cold because, needless to say both the vacuum tube and the sensor wire are right by the red hot manifold where you can't fix them when things are hot.
Anyone else experienced this?
When they ran the diagnostics it showed that it was a problem with the air mix. When the car is cold there's a little vacuum pipe that feeds fresh air into the exhaust manifold to ensure dilution of any unburned gas particles (my explanation! lol) So, either the vacuum pipe is loose or (sometimes) the sensor wire is malfunctioning. My Service Representative says they often cut the wire and replace it with a bigger wire that can handle larger resistance.
So engine check light re-set. If it comes on again when I do a cold start it means a trip back to the dealer...and I have to leave it for the engine to get really cold because, needless to say both the vacuum tube and the sensor wire are right by the red hot manifold where you can't fix them when things are hot.
Anyone else experienced this?
AudiWorld Senior Member
Joined: Jun 2000
Posts: 647
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Re: Oh oh, engine check light on!
As far as I understand, the reason fresh air is pumped into the exhaust manifold is to further oxidize unburned hydrocarbons in the exhaust as it passes over the catalyst. The platinum in the catalyst needs oxygen to do its work, hence the fresh air.
While 'dilutive' to a degree, pumping more air into the exhaust stream from a physical standpoint merely increases the velocity of flow. As such, this method wouldn't show a net decrease in harmful gas emissions were it not for the chemical reaction at the catalyst being improved by added oxygen.
Just thought you all might like to know.
While 'dilutive' to a degree, pumping more air into the exhaust stream from a physical standpoint merely increases the velocity of flow. As such, this method wouldn't show a net decrease in harmful gas emissions were it not for the chemical reaction at the catalyst being improved by added oxygen.
Just thought you all might like to know.
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Yes it is! Chris, maybe you should call PBIS...
despite the agony that might cause. I have PacHell DSL and internet access, though they don't host my evan.com domain and email. I'm sending out through PacBell though, and everyone else is getting my mails. Something is just not right with how they have you set up. Perhaps some screwy DNS thing with your cjlloyd domain?
New Member
Joined: Oct 2000
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Re: had the same problem
Did you have a Forge or Bailey DV installed ? My engine light also came on a few weeks ago, and the dealer removed the Forge valve and replaced it but had to replace the " air flow meter " also. I am not sure about the term for the part. The forge was sent back by me and had some new internals replaced, and I haven't reinstalled it yet. The dealer said that the stock DV was designed for a different " pressure setting " than the Forge. Pete at Stratmosphere said that was BS. Can anyone comment on this since I don't know anything about it and don't know who is correct. Thanks.