Idles fine but no power...and backfires.
#1
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Location: Easley, SC / '86 951 / '02 A4 Quattro Sport
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Idles fine but no power...and backfires.
Here's the story. I was accelerating in 3rd gear to about 5K rpm and I then felt a noticeable hesitation. I let off the gas and there was no engine braking sensation at all. I gave it throttle and there was no more power. It began to backfire and would not accelerate. I had to limp back to the house(luckily only a mile or so) The car seems to run fine at idle, just nothing under load. I'm thinking maybe it skipped a couple teeth on the timing belt and possibly bent a valve...any ideas. Thanks.
-Pat
-Pat
#2
Nordschleife Master
Here's the story. I was accelerating in 3rd gear to about 5K rpm and I then felt a noticeable hesitation. I let off the gas and there was no engine braking sensation at all. I gave it throttle and there was no more power. It began to backfire and would not accelerate. I had to limp back to the house(luckily only a mile or so) The car seems to run fine at idle, just nothing under load. I'm thinking maybe it skipped a couple teeth on the timing belt and possibly bent a valve...any ideas. Thanks.
-Pat
-Pat
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Thanks for responses! I'll check those things out and report back. It was the part about the no engine braking while in gear that led me to think maybe a valve issue. I'll definitely be much happier if it's just a hose or coupler though
-Pat
-Pat
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It's an hour straight down 25 basically. Hopefully it is something simple. I'll post up either later today or tomorrow with an status. Thanks.
#10
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If this is the unit connected directly to the airbox then I believe it may be the culprit. I only had a few minutes looking at it but could hear the rushing sound of air through it at idle. That is definitely not the normal sound under the hood when idling. When I manipulate the throttle by hand the car stumbles as if it is about to stall. Also, while it was idling I removed the connector plugged in to the unit and the car died, which I expected, so it appears that bit is functioning.
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You might also check the hose that comes off the turbo to the intercooler. I had one that split on the underside, just past the hose clamp. Sounds like you have a hose blown past the turbo.
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The other suggestions are right on but also; see the small screw at the very center of this pic (top of the throttle body), is yours missing/hissing from there - those little puppies get blown out sometimes... Bruce
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Okay so I finally had some time to look at it. The rubber couplers on the intercooler look fine as do the others. When I pull the connector from the tps the idle comes up and it seems to rev better without stumbling so I'm leaning that way. What is the best way to test the tps and afm? I'm guessing I would need a volt meter to check the signals. BTW the set screw on the tb is still intact and has not moved from it's normal spot. Thanks!
-Pat
-Pat
#14
mine was do'ing the same thing when my tps went.New tps fixed it ,then a few months later was getting similar simptoms, but not as bad. found torn bypass valve diaphram. repaced that and now all is well.