01 Trans Am LS1 vibration
07-16-2016, 11:35 AM
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01 Trans Am LS1 vibration Hello, first, thanks for the forum, it's been wealth of information to me during my first LS swap into a Gen2 F-Body (71 Camaro).
But, I just picked up a 2001 T/A WS-6 6 speed car and its got an odd problem. I thought I'd run it by you'all and see what your thoughts are. As I said, I just got this car and know zero about its history. Its a super clean, very tight, great driving, 100k mile car.
It has a moderate vibration that starts around 1700 RPM's. It stays consistent with higher RPM's, smooths out a little in some spots, but is there pretty much anywhere above 1700 RPMs. Seems slightly worse cold, but not really.
When I got the car it had a bad o2 sensor, upstream. At first, I was sure it was the cuprit. Nope. Although it did run slightly better, the vibration was still there as strong as ever.
Second, we found a couple weak coil packs. Bingo! Thats gotta be it! Nope, it did run slightly better, much less reported misfires, but the vibration remains. Plugs all looked great. One was questionable with a hairline crack, so it was replaced.
Well, its got to be a bad harmonic balancer, right? So, we installed a new 25% underdrive balancer thinking this has to fix it! Nope. Vibration might be 10% better, but still there big as life.
While under the car, I noticed that there was some writing on the tranny, about a year ago it looks like it had a clutch. Note says, 'thin shim only' with the date.
I guess it could be the flywheel or a tranny alignment. The vibration exists with the clutch engaged or not. Clutch operates and engages perfectly.
I've also noticed that upon 1/2 throttle or greater, the AC vents will change and start blowing out of different vents. This may indicate a vacuum leak(s). I have doused the top of the motor with brake clean, nothing changes.
Another note. I haven't driven one of these cars in many years, but have owned a 98 and a 02 before. Both automatic cars. If my memory serves me correctly, they both ran quite a bit better than this car. It seems down on power at least 25%.
Ideas I have from here are:
Bad wires, although they all look fairly fresh and good.
Replace the plugs, although they all look great.
EGR issue?
Bent pushrod, (not sure how to narrow that down)
Flywheel
trying to explain the low power situation coupled with the vibration, so things like the flywheel are lower on the order of possibilities, at least in my mind. I could be just remembering these cars faster than they really were! Seems like my 2002 back on the day would absolutely roast the tires, not sure this one would do more than chirp them.
Currently, there are no codes.
Starts and idles exactly like it should.
Any ideas on what to look for next? I hate throwing parts at stuff! Thanks so much!
But, I just picked up a 2001 T/A WS-6 6 speed car and its got an odd problem. I thought I'd run it by you'all and see what your thoughts are. As I said, I just got this car and know zero about its history. Its a super clean, very tight, great driving, 100k mile car.
It has a moderate vibration that starts around 1700 RPM's. It stays consistent with higher RPM's, smooths out a little in some spots, but is there pretty much anywhere above 1700 RPMs. Seems slightly worse cold, but not really.
When I got the car it had a bad o2 sensor, upstream. At first, I was sure it was the cuprit. Nope. Although it did run slightly better, the vibration was still there as strong as ever.
Second, we found a couple weak coil packs. Bingo! Thats gotta be it! Nope, it did run slightly better, much less reported misfires, but the vibration remains. Plugs all looked great. One was questionable with a hairline crack, so it was replaced.
Well, its got to be a bad harmonic balancer, right? So, we installed a new 25% underdrive balancer thinking this has to fix it! Nope. Vibration might be 10% better, but still there big as life.
While under the car, I noticed that there was some writing on the tranny, about a year ago it looks like it had a clutch. Note says, 'thin shim only' with the date.
I guess it could be the flywheel or a tranny alignment. The vibration exists with the clutch engaged or not. Clutch operates and engages perfectly.
I've also noticed that upon 1/2 throttle or greater, the AC vents will change and start blowing out of different vents. This may indicate a vacuum leak(s). I have doused the top of the motor with brake clean, nothing changes.
Another note. I haven't driven one of these cars in many years, but have owned a 98 and a 02 before. Both automatic cars. If my memory serves me correctly, they both ran quite a bit better than this car. It seems down on power at least 25%.
Ideas I have from here are:
Bad wires, although they all look fairly fresh and good.
Replace the plugs, although they all look great.
EGR issue?
Bent pushrod, (not sure how to narrow that down)
Flywheel
trying to explain the low power situation coupled with the vibration, so things like the flywheel are lower on the order of possibilities, at least in my mind. I could be just remembering these cars faster than they really were! Seems like my 2002 back on the day would absolutely roast the tires, not sure this one would do more than chirp them.
Currently, there are no codes.
Starts and idles exactly like it should.
Any ideas on what to look for next? I hate throwing parts at stuff! Thanks so much!
07-16-2016, 03:20 PM
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