Engine hesitations

[dump]

Hello guys,

My Rs4 b7 makes me crazy

For several months, she has engine hesitations between 2000 to 3000 rpm as soon as the engine start eating. Before 50°C, it runs perfectly. No hesitation, engine revs perfectly from 0 to 8000rpm+

When the engine is at 90°C, I can feel hesitation. Sound exhaust is also changing with strange high sound noise like a whistle

Car smell gasoline at the exhaust, she seems to run rich, black smoke sometimes at high rpm

https://youtu.be/dyxVM08fRzU

After 3500rpm, she’s running perfectly until 8250rpm.

Here is what I already changed:

Spark plugs x8
Ignition coils x8
Lambda sensor x2 (before kat)
Mass airflow sensor
Carbon cleaning
PCV valve
Air filter
Gasoline filter

-Zero defaults on the VCDS
-No misfire even by driving between 2/3000rpm when hesitations are there.
-Flaps are still there and working well, no game, they move easily. No chip tuning, no modification.
-Fuel pressure seems to be ok

Pleaaaaaase Heeeeelp, I’m lost…

[dan32v]

....with strange high sound noise like a whistle

Be careful, sometimes it is the membrane of the oil separator (or PVC) that is pierced...

[dump]

....with strange high sound noise like a whistle

Be careful, sometimes it is the membrane of the oil separator (or PVC) that is pierced...

I know, but the sound is coming from the left exhaust, no noise close to the engine

[dan32v]

Exhaust manifold leak ?

[dump]

Nope, hissing is coming from the muffler

Check my video on my first message

My first idea was injectors, but unfortunately there is no way to test them even with the VCDS. I don’t want to disassemble them and spend 1.5k€ for nothing

[dan32v]

OK.

I think it turns like a potato.

It sounds like a valve leak...

[dump]

I know…

Engine is running perfectly until it starting to heat.

It’s worst when outside temperature are high.

I did a diag with my VCDS yesterday, and still no fault code

[dan32v]

Indeed, it will not be easy to find the cause or the faulty sensor without a defect report except a stroke

of luck...

In any case, there is a sensor that changes state or gives wrong information depending on the

temperature.

[dan32v]

Variable Valve Timing Failure – Audi 4.2 V8

Audi’s V8 engines use variable valve timing technology, commonly referred to as VVT or Vanos. The system variable alters the position of the camshaft, allowing for more precise intake and exhaust valve timing.

The system uses a VVT Solenoid which is actuated via oil pressures to control the camshaft timing. These solenoids frequently get clogged or gunked up which can cause them to fail and lead to performance and timing related engine issues.

https://www.ecstuning.com/b-genuine-vol ... utm_term=1

[dump]

Indeed, it will not be easy to find the cause or the faulty sensor without a defect report except a stroke

of luck...

In any case, there is a sensor that changes state or gives wrong information depending on the

temperature.

That’s true and I know that it will be not easy to find which one…