Don't know if this is the correct forum or not but I have an '02 Z28 A4 with 42k miles on it that seems to have an internal engine vibration, or so it seems to me? I can only feel the vibration through the center console and my rear through the seat.

Specifically at 2100-2400 RPM when revving and stationary. I have done the following:

-Unbolt torque converter so it does not spin, then rev the engine, vibration is still there.

-Swapped crank pulleys with a known good GM replacement, still there.

-Checked flexplate through inspection hole and cover where starter is, no visable cracks at all.

-Removed belts for a short and quick test.

-Pulled all pushrods, all look straight to the naked eye, but about 6 don't roll "perfect" and look just ever so slightly bent. Either that or poor manufacturing. Would think this might cause a little bit of a misfire, not a vibration?

Valve springs look intact and no misfire codes. Injector pw's are almost dead even on both sides. I'm kind of at a loss as to what it could be? Any suggestions would be greatly appreciated!


Mods to the car: QTP long tubes, true duals, tune, 3.73s, Volant CAI.


Sean

 

Have you installed a Poly trans mount? My car developed this after my stall/built trans install....I also put in a poly mount, and I think thats the culprit

 

I have the same vibration.Thats funny,mine is an 02SS
with almost same miles and mods.The vibration was
always there,I just notice it more now with the
headers and conveter.I have heard a few people say
the same.Keep us posted if you find a cause

Brian

 

Defiantely replace those. They should be straight. It is hard for me to think how you bent them since you have an A4. Most people with bent pushrods have manuals and bent them missing a shift( 2->1 rather than 2->3 or 4->3 rather than 4->5 ) and over reving the car. Has the car been bouncing off the rev limiter much?

Keith

 

I have this vibration too.More so with the poly trans mount,but one day it got real bad. I looked under my car and noticed that my passenger side hedder was touching a heat shield.I pushed up on the heat shield and most of it whent away.Some of it still there,but its because the poly trans mount

 

FWIW: This is my car and I have it at a reputable shop for determination of what's causing the vibration. It has been put against the rev limiter (which is set at 6100 rpm) a couple of times. I know I should let the computer shift for itself but there have been a few times when I 1st purchased the car that I tried shifting myself. Slightly bent pushrods being the result.

Still wondering what is causing the rpm dependent vibration though. I have an aftermarket torque arm with a poly mount but the tranny mount remains stock.

 

Ordered some chrome moly pushrods from TSP, will report back. I can't imaging the torque arm mount transmitting that much vibration, poly trans mount yes, but it is the original GM trans mount and is still in good shape. Hmmm .

 

Update, installed new pushrods, vibration is still there, ugh. Wonder if a poly torque arm mount would cause a vibration? Will disconnect and try.


Sean

 

Is this something that just started or has it been there? Have you done a compression, cylinder balance test?

 

Customer does not remember it being there when the vehicle was initially purchased. Seems to have started after some rear end work, doesn't make much sense since the vibration is there when the vehicle is stationary, possibly a coincidince. I disconnected the exhaust and torque arm mount, no change. Swapped transmission mounts, no difference. It must be in the engine somewhere. I will perform a compression test, although the car runs like a top, low 13s @ 106mph here in Phoenix.


Sean

 

Sorry to bump, but any update on this? My vehicle is doing something similar.