C4 AAT Vibration: Causes and Solutions

Hi!

Short question: When I first installed the chip, I could feel a vibration between 2000 and 2300 RPM, but it disappeared once the engine speed exceeded that. Now that I'm not feeling it anymore, I'm just wondering why it's gone.
Could it be that there is currently less of it because pressure builds up in this area?


Best regards, Marko.

Hello!

I can't say anything about the question asked above, but I also experience this annoying vibration (even within the same RPM range, and even after installing the chip)! Without the chip, you can only provoke the vibration by accelerating under full load in a higher gear (e.g., 3rd or 4th gear) while being under-revved (sometimes it's gone, and in that RPM range, the car pulls better and makes less noise!). By the way, I also have an uneven engine idle between 1000 and 2000 RPM, which causes the whole car to shake a bit (it manifests as annoying jolts when starting in gear). The car has also been to a Bosch service center, but they say everything is fine !
I've also been thinking about the boost pressure buildup, but what could be the cause? The turbo shouldn't be faulty, because sometimes the vibration disappears and the power delivery is better?! Is it possible that the boost control valve is slightly worn and can't regulate the boost pressure accurately during buildup?
So, I'm curious to see if any of you can help me!

Best regards from Austria.

Andi.

Audi 100 2.5 TDI AAT, 115 hp (with chip tuning, 140 hp), manufactured in January 1994.
150,000 km