HELP - RS7 rough idle, no boost

[zabds319]

2017 RS7. Stock turbos, 25,000 miles. APR stage 1, catted Redstar DPs and SRM intakes. Had all of that for 10,000 miles or so. Regular oil changes obviously.

Today was driving normally, and then turned one corner and hit the gas and noticed no boost. I was at my destination and didn’t have time to test it out much. I parked the car and noticed the idle was rough. 2 hours later left, car started fine, although idle was rough. Car drove ok but since it wasn’t warmed up I didn’t punch it and test the boost. 10 min highway drive taking it easy, no issues, and got off the highway and when I approached a stop the engine got very rough, drove 6 more blocks home and when I pulled into the garage the idle was the roughest yet by far.

On the gentle 6 blocks home I gave it a little gas and could hear the turbo whirl but zero boost on the gauge. At home the idle was so rough that once in park the engine damn near stopped and like started itself back to life a couple times. I didn’t turn it off immediately just so I could get the video. And it smells horrible, far stronger than catless downpipes for example.

See videos of engine bay, and you can almost hear better at the rear how rough the idle is. But you can see the engine moving.

Zero check engine or other lights. I have a simple OBD code reader and no codes.

By default I’m obviously most worried about turbo failure… Are the turbos the culprit? Boost leak? Neither of those would explain the rough idle or shutting off while coasting though right? Spark plug? Ignition coil? I am absolutely not a mechanic. The dealership and good shops around me have a months-long wait to get in, which is frustrating obviously, but I’m dying inside to at least have an idea of what it is.

Edit: trying to figure out how to add videos


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[zabds319]

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[kabukie]

Chicane in Olathe is a trusted shop with the KC Audi group.
Most people seem to have luck getting in with them quickly

[rabbitdog]

I see your passenger side wastegate actuator seems to be moving it in your second video. Mine doesn’t do that.

[GlacierS5]

Damn! Pull the SRM inlets off and check for any shaft play.

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[VinnysS4]

+1 for turbo inspection. If the oil feed screen hasn't been taken out/care of... that's 5 years on the screen.
That being said, the wastegates bouncing like that looks more like a vacuum iissue.has the pcv been taken care of?
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[zabds319]

+1 for turbo inspection. If the oil feed screen hasn't been taken out/care of... that's 5 years on the screen.
That being said, the wastegates bouncing like that looks more like a vacuum iissue.has the pcv been taken care of?
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Thanks for the replies.

No on the PCV… I don’t think my car was eligible for the service covered by Audi.

I’m just curious if folks here think a boost leak or wastegate problem would cause such a rough idle? I have very little knowledge of this stuff if I’m being honest.


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[ericw.]

My guess is turbos and metal is in the engine. Real bad move to run the engine without inspection.

[VinnysS4]

I’m just curious if folks here think a boost leak or wastegate problem would cause such a rough idle? Audizine Forum

No and no


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[edg71908]

Any update? Just started having this same problem yesterday. I'm at 41k so need to do plugs and hopefully that is it!

[zabds319]

Any update? Just started having this same problem yesterday. I'm at 41k so need to do plugs and hopefully that is it!

Turbos. Actually just the passenger side turbo. The shop is confident there's no other damage so hopefully they're right and I should be good once I get the turbos replaced... but I guess there's always a chance there could be some issue not yet seen, so I was holding off on updating until I have it back and running smoothly. I'll post some pictures eventually. Pretty sad at 25,000 miles for a $150,000 car in my opinion (regardless of a tune).

[Alabama]

Turbos. Actually just the passenger side turbo. The shop is confident there's no other damage so hopefully they're right and I should be good once I get the turbos replaced... but I guess there's always a chance there could be some issue not yet seen, so I was holding off on updating until I have it back and running smoothly. I'll post some pictures eventually. Pretty sad at 25,000 miles for a $150,000 car in my opinion (regardless of a tune).

The recent turbo warranty extension may not help you, but it is surprising that an RS turbo failed like this.

[zabds319]

The recent turbo warranty extension may not help you, but it is surprising that an RS turbo failed like this.

Agreed. Curious to see what the oil screen looks like

[VinnysS4]

25k miles is ridiculous low mileage for failure too

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[zabds319]

Public service announcements: remove or replace your oil screens!

5000 mile oil changes is not enough. This is my screen at 25k with 5k changes.

IMG_1319.jpg


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[zabds319]

And here’s the passenger turbo. The shaft is snapped and can hardly even spin, which I’m told explains the rough idle.

Engine was fine. Interestingly the driver side turbo is pristine with no shaft play.

Do these turbos have any value? I obviously have no use for them.

I went SRM +4mm and with my SRM intake and Redstar downpipes I’ll be doing DS1 stage 3 unless someone talks me out of it.

image-2022-03-09-20:45:20-143.jpg


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[9times]

Do these turbos have any value? I obviously have no use for them.

I went SRM +4mm and with my SRM intake and Redstar downpipes I’ll be doing DS1 stage 3 unless someone talks me out of it.

First, sorry that really sucks; second, way to make lemonade.

Yes, you should be able to recover a good chunk from your stock turbos! For the least hassle you can sell them as-is and let someone else rebuild one/both, or for a little more work have the bad one rebuilt to stock and sell them as a stock pair. I guess you could rebuild the bad one to +4mm and sell them separately, but that may take longer (?) Having them both rebuilt to +4mm may be another option, as you could get more from the +4mm pair, but you'll have to do that tradeoff with real numbers or maybe someone smarter than me already knows. But you definitely have options. New RS+ turbos go for what, $1700 new, people are asking $1500 refurbished.

DS1 is a no-brainer IMO. I've barely scratched the surface of the tuning capability, incredible support and user community. I just flashed the DS1 OTS Stg 3 S6 tune over APR stage 3, and besides just getting a lot stronger tune now I get to learn how to do it myself, by starting with a proven map and making slight adjustments in a safe environment.