Absolutely befuddling idle vibration...need the big guns
Steps taken:
Lifted car on all corners
replaced exhaust bracket rubber mount, no change
put car in gear in the air and poked around for vibration. Could not find an obvious source.
the harmonic dampner looks like its got some vertical runout to it but it looks similar to the original and every other m113 i've seen so I don't think thats the problem.
I used a floor jack to support the motor, no change so i believe my motor mounts are ok.
one weird shifting oddity i've noticed lately. After the car shifts, it bogs for a milli-second before re-engaging the power. So instead of a smooth flow of power through the shift, there is a little hiccup. Not motor related.
Drove it on the highway and got excellent smooth performance with good fuel economy. If you were on the highway you'd think the car was just fine.
If I end up keeping the car, I think torque converter is something I need to have replaced.
Have you changed out the original balancer for another, is it an OEM new or used. A vertical run out could be the source of you issue. Do you see any tensioner movement caused by the runout?
Have you changed out the original balancer for another, is it an OEM new or used. A vertical run out could be the source of you issue. Do you see any tensioner movement caused by the runout?
The issue did not start after replacing the dampner and there is no play when i try to move it with my hand. Unless it spun the outer part on the inner, then i'm not sure why it would be an issue.
I'm more and more convinced its a torque converter.
From everything you have stated this is a mechanical issue or noise & not related to tuning & electronics. It might be a harmonic or primary mechanical noise. The fact that it only occurs when you load the engine is telling.
It could be anything from something touching e.g. exhaust heat shield, to a rear tranny mount, to a TC, to a piece of Cat monolith that has broken off, to a loose tail shaft flange nut on the transmission, the EECS circuit & purge valve or sympathetic vibration that needs to be moved out of the audible spectrum. The joys of NVH engineering.
I suggest you buy a $5 mechanic's stethescope, place the car on a hoist with brakes on & in Drive & tie down exactly where the noise is emanating from.

Good Luck
1. The TC doesn't appear to make any unusual noise. If you can post a soundclip that would be great.
2. I have checked exhaust heat shields and found no issues. Trans mount is essentially new.
3. There is no rattling from the Cat, 02 sensor readings are normal, and the car gets good gas mileage with good power. I would think a Cat issue would affect performance.
4. what is the EECS circuit? the purge valve I'm guessing you mean the fuel tank/charcoal canister fume purge? It ticks like normal when its working.
5. I used the mechanic stethascope and found nothing.
I held onto the front halfshafts while at idle and noticed nothing unusual.
thanks again guys.
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Apologize, just did a google search for Corteco harmonic balancer issues and found this, it seems this fellow has run the gauntlet trying to find out his vibration issue.
I continue to go back to the torque converter.
If you are in for some experimenting, remove the serpentine belt and using some tape fasten securely a small 1/4 oz wheel weight to the outside of the balancer, start the car and see if there is any difference in the vibration. Idle only. While you are placing the weight check for bulging rubber.
If you are in for some experimenting, remove the serpentine belt and using some tape fasten securely a small 1/4 oz wheel weight to the outside of the balancer, start the car and see if there is any difference in the vibration. Idle only. While you are placing the weight check for bulging rubber.
I checked for bulging rubber while under the car the other day and did not notice anything untoward.
Will try the weight trick as well.
thanks man, really appreciate the ideas.




Cheers,
maw
If you prefer remove the throttle body from the back of the super charger and clean it off the car.




Did you ever get yours sorted?
maw





