1G Vibration and power loss under load

[cjridert1]

A few months ago the car ran great, next time I drove it, it felt like the clutch was slipping (low mileage PTT). RPMs were going up, drivetrain had a bad vibration to it (only when boosting, having symptoms by 10psi), and it was making bad power. Let off the gas and it runs normal.

I took the clutch out, looked good, but sent it anyhow. PTT says everything is in spec and looks great. The car cruises and shifts perfect. Transmission oil looks good. axles look good.

Any ideas? Log attached

 

[weasel1G]

I would check plugs, wires first. Sounds like a bad misfire. Do you run E85?

 

[zedicus]

i had something very similar happen in my 1g a couple years ago. weirdest thing i ever saw after chasing my tail for weeks. the battery hold down clamp had the end broke off of it and even though it looked fine it wasnt actually holding the battery in. just as the boost would start getting good there would be a terrible vibration and the engine kept spinning faster but the power tanked. but i could cruise around all day and even lightly boost fine. i guess the vibration from the batter and battery tray bopping on the intake hose would either temporarily unseat the hose or something.

anyway im not 100% sure on HOW it affected it but one day i tore off all the intake piping, seen the broken battery tray bracket and fixed it just to fix it, found no issues so i put all the intake tubes back on, happened to go for a drive and started spooling 32psi with no issues.

(im not saying its going to be identical for you but pull the intake tubing apart and look for brackets that are close that might be doing weird things under load of engine)

 

[cjridert1]

I would check plugs, wires first. Sounds like a bad misfire. Do you run E85?

Wires are new, Ill try new plugs (hopefully next week). Just 93 + methanol

 

[JS4G63]

Another thing you might want to check is your driveshaft carrier bearings and u-joints. If the carrier bearings are really worn out, the driveshaft can move around enough to bind up a bit under load.