Backfire Anyone?

[libbygrosch]

Greetings all,
I was hoping I could get some input as to why my TT is backfiring. It doesn't do it all of the time, but when it does it's usually shifting between 2nd gear and 3rd. I thought it may have something to do with the plugs. I changed them out (they looked bad and smelled burnt) and added some fuel injector cleaner to try to get around taking off the fuel rail and soaking it. Once I changed the plugs the problem subsided for a few days, but is now doing it again??? I just bought the car 3 months ago and have already had to have the air compresser and clutch for the compressor replaced ($2000...ouch). I am also having, like alot of people it seems, electrical problems. Any ideas would help.

Libby

[Kelvin]

Hi libby,

I am not expert enough to say why but the underlying cause it excessive unburned fuel so anything leading to that could be the cause. I have just replaced the MAS which was causing some bad idling and loss of power but not backfiring. I am guessing, but it may be possible that in an extreme case it could cause this too. Another guess would be faulty spark plug leads and even dirty injectors.

[libbygrosch]

Originally posted by Kelvin@Feb 13 2005, 12:35 AM

Hi libby,

I am not expert enough to say why but the underlying cause it excessive unburned fuel so anything leading to that could be the cause. I have just replaced the MAS which was causing some bad idling and loss of power but not backfiring. I am guessing, but it may be possible that in an extreme case it could cause this too. Another guess would be faulty spark plug leads and even dirty injectors.

Quoted post

Thanks for the advice. That sounds like a good place to start.

[cheesemax]

This is pretty simplistic and I'm sure you've thought of it but,,,,,,,
Are you using the highest octane available? I find Audi engines are very sensitive to using the right fuel and have mis fire issues with mine when not using the highest octane.

[Kelvin]

Good point cheesemax. Always good to go simple before hitting complex!
We only get two grades out here and I always use the highest. As a matter of interest, what octane are you using normally and which gives you problems?

On a similar point, in South Africa, we are always very conscious of the tailpipe colour as a first sign indicator of good tuning and typically consider that if we see a pale grey colour all is well. Out here, I have never seen this and all pipes are pitch black. Any thoughts?

[cheesemax]

The highest octane we get here is 94. Anything below 92 and I get the "check engine" light glaring at me. This is usually due to the oxygen sensor that sometimes seems to have a mind of its own (lol). I waisted a couple of trips to the dealer only to have them re-set the computer and send me on my way. After some research, I found out that it will actually re-set itself after a couple of days. If it doesn't re-set itself it could mean there is a some other (more serious?) problem.

[libbygrosch]

Originally posted by cheesemax@Feb 16 2005, 10:34 AM
The highest octane we get here is 94. Anything below 92 and I get the "check engine" light glaring at me. This is usually due to the oxygen sensor that sometimes seems to have a mind of its own (lol). I waisted a couple of trips to the dealer only to have them re-set the computer and send me on my way. After some research, I found out that it will actually re-set itself after a couple of days. If it doesn't re-set itself it could mean there is a some other (more serious?) problem.

Quoted post

KISS right? I have been getting gas at the same place, it's 92 Octane. I may try finding a higher octane and see what that does.