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Misfire, no acceleration, rough idle

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Misfire, no acceleration, rough idle

Old 07-21-2018, 06:53 AM
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These are the gaskets your speaking of correct? Fuel Pump Gaskets
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Old 07-21-2018, 07:04 AM
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Thats it,my mechanic installed this one also

https://www.ecstuning.com/b-genuine-...it/4d0298135b/
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Old 07-21-2018, 07:26 AM
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As was pointed out earlier, low-erratic fuel pressure from a failing pump could do this.

As an alternative theory, have you replaced the O2 sensors lately? My son's 2001 A8L had one go out awhile ago and it ended up with most of the codes
you listed, since the bad sensor was causing the fuel trims to get all out of whack. One easy way to check this is to clear the codes with a reader and pull the battery ( have your Radio Code handy!). Come back in an hour, re-attach the battery and re-start it. If it suddenly runs better with the factory default fuel trims that's a pretty
good indication of a bad O2 sensor.
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Old 07-21-2018, 07:55 AM
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No I haven't replaced the 02 sensors lately. I take it there is more than one? Is one more prone to failure over the other? What is the radio code and how do I find it? Does it have something to do with the security system?
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Old 07-21-2018, 08:38 AM
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There are a total of four O2 sensors: two upstream and two downstream. Radio security code can be gotten from Audi Dealer, but they will most like charge you for it.

See link in my signature for info on O2 sensors.

Good luck.
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Old 07-21-2018, 08:59 AM
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The other forum is quattroworld. Radio code might be in your owner's manual, maybe on a card. You also do not need it if it's the original head unit to the car, if so it won't ask you for a code (I believe).
Personally I do not think O2 sensors can strand you unless maybe there is a serious wiring issue, the ECU should decide they are way out of range and throw an O2 sensor code before they might degrade to the point of noticeably bad running. I could be wrong, of course. It happens.
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Old 07-21-2018, 09:36 AM
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Upstream O2 sensors do all the heavy lifting. The passenger side one is a PITA. It IS a long shot, admittedly, but it's easy to RESET to factory fuel trims without a lot of work. Much less work than swapping the fuel pump anyway.

My Radio Codes have generally been on a card/label inside the "Entertainment System Guide", not Owner's Manual. If you bought used or didn't get the Guide then the dealer can recover. I've always thought they goofed up when they built the head unit-- If it's "unlocked" you should be able to display the code from the front panel. But, as far as I know you can't
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Old 07-21-2018, 09:39 AM
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@jfrahm

Yeah, I'd think the evidence would lean toward Fuel Pump-- and he should definitely replace the filter before the pump.
But I did have one in the fleet recently show basically this set of codes-symptoms where the fuel trim was all out of whack. Bad O2 sensor replacement fixed it.
Likely a fluke, but I always like to try the easy stuff first if there's a chance.
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Old 07-21-2018, 09:47 AM
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I found my radio code so that's not an issue. I sprayed some started fluid into the intake and it started for a brief moment but then immediately died. I tries to idle it's just very rough and low rpm. I was able to get one rev out of it before it died. So I'm thinking it's the fuel pump. My experience with fuel pumps has always been it won't idle at all. That's what has me thrown off.
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Old 07-21-2018, 09:53 AM
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Have you done the fuel filter lately? I'd probably do that first if it's been a long time.
Fuel Pump is generally the #1 "won't start" issue. I've gotten tired of wondering what the pressure actually is up on the rail (since there's no Test Port) so have tended to retrofit a 1/4" NPT port up there to check it on our cars, just because it's a PITA to swap the actual pump.

I only mentioned the O2 sensor fuel trim angle since I've had one car do that-- rough idle, run like kraap, hard start. Fortunately they tend to run rich when that happens.
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