Vibration Under Acceleration - Another Post

[JZeke]

I also have this driveline vibration under acceleration but zero vibration revving the engine warm stationary. 2003 3.2, 79k miles. Figured a new post might get more views than thread jack.

work done to date (last 3 years);

• Gbox gearbox rebuild - 2nd gear/new hardware
• alignment at a porsche indy shop
• TRW track arms/hardware
• TRW endlinks
• Clutch, RMS (no leak, preventative) - DMF “good condition” (indy shop)
• LN IMSS (indy)
• front engine mount
• coil packs/spark plugs
• throttle body cleaning, MAF cleaning

Vibration is only present under accel (most felt 2200-4000 rpm but smooths out/less noticeable approaching redline) and in all gears, what’s the proper way to diagnose the fix? Of these 4 potential culprits: DMF, lower control arms, axles, transmission mounts - which is more likely to cause these symptoms? Engine revs smooth when stationary after being properly warmed, no vibrations at idle bar a ~25rpm flutter. Engine pulls hard, revs beautifully and power seems very strong. No codes present.

Before I phone an indy/dealer want to see if I could solve it and learn something in the process.

[Gilles]

Have you check the front engine mount?
There are a few different ways to check it, one is driving in a lower gear and quickly apply and release the throttle.
Another is to have another driver in your car while you follow closely and after they apply and release the gas pedal the tips of the exhaust will move up and down more than they should..

[JZeke]

Originally Posted by Gilles

Have you check the front engine mount?
There are a few different ways to check it, one is driving in a lower gear and quickly apply and release the throttle.
Another is to have another driver in your car while you follow closely and after they apply and release the gas pedal the tips of the exhaust will move up and down more than they should..

Yeah, I replaced this a couple years ago and it made a world of difference - it was impossible to get a clean shift, now no issues. Though at times there have been a bit of graunch with imperfect shifts. I usually chalk that up to bad driving, but I'm thinking the transmission mounts might have a little play in them.