Sputtering at idle

2005 AUDI A4
120,000 MILES • 4 CYL • TURBO • 2WD • AUTOMATIC
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Friend of mine bought this car as is, it was very inexpensive. She was acting bad first as far as dash flashing and so forth we put a new battery all was good, but it kept having a check engine light on and a sputtering, rough idle at start up. Even when it's warm, same thing, but only at idle. If you rev it up smooth as silk, if you drive it, very very smooth.
Code was for the thermostat heater element, mapping thermostat I believe. Replaced it and code was gone. Still sputtering. Had misfire on 1 and 3. checked hoses and found the bottom PCV part underneath the intake was broken, replaced it and gotten better. Found another hose cracked along the PCV system, replaced it, gotten better. Found the plugs black, replaced them and coils as well. Kept getting diverter valve code, removed it and checked it with vacuum gauge and works fine, put it back, still getting misfire on 1, 3, sometimes 1, 2, 3.. checked the valves when I replaced all this stuff and they are very clean.. checked many vacuum hoses can't find one with a leak or a crack anywhere.
Dec 31, 2020 at 1:49 PM
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Attached.
Dec 31, 2020 at 1:55 PM
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This sounds like a low compression issue. let's start by removing the plugs and checking the condition (in order) and sending pics of them. Here are guides to help with the repair:

https://www.2carpros.com/articles/how-to-test-engine-compression

and

https://www.2carpros.com/articles/engine-misfires-or-runs-rough

Let us know what happens and please upload pictures or videos of the problem.
Jan 1, 2021 at 11:30 AM
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oh, forgot to mention that compression is very good, plugs are new, coils new.. I found the pressure relief valve which has a diaphragm has a tear, ordered one hopefully that is the issue.
Jan 1, 2021 at 11:32 AM
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Let us know what happens and please upload pictures or videos of the problem.
Jan 4, 2021 at 8:26 AM
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it was the PCV on top of the motor, changed many things to make it stop misfiring, hoses, etc. dang Audis always have these issues. Now I need to replace this small part, the little hose broke off of it. do you know what it's called? greyish piece in the picture.. I just put a screw in the line for now so no vacuum leak would occur.
Jan 16, 2021 at 12:28 PM
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good job finding the issue that is a vacuum check valve off of the intake.
Jan 18, 2021 at 6:20 PM
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Would that make the car stumble and shut off sometimes? It does that randomly since that dang hose broke on it.
Jan 18, 2021 at 6:36 PM