CantStopTheFox...

What's up guys!

Started about 2 weeks ago....(I swear it was after I put some cheap gas from Lukoil in it)....but at 1000 – 1500 RPMs, the motor runs really rough, and the entire car shakes really bad.

It is whether I am in neutral or on the road...

When it sits idle at 900, it is fine. Once it passes 1500 it is fine. But anywhere in between....it runs very rough....so rough that my dash-mounted tach looks like it is going to fall off!?!

I checked under the hood and it seems to be a little louder on the passenger side, but nothing looks out of the ordinary.

Any advice would be greatly appreciated!

droptop302

Did you check the HB (Harmonic Balancer)

CantStopTheFox...

I actually had issues with the balancer in the past. The rubber ring was slipping out the back, causing it to wobble....so I replaced it, and it is very tight (I just threw a wrench on it to make sure).....but it still wobbles a little bit. It actually leaks a little oil from there as well. I think the crank may be a little bent.

Could the crank be bent...(or warped enough to make a "tight" balancer wobble)?

droptop302

I do not think you crank is bent. Did you get a stock HB or aftermarket? Stock ones are cheep cheep cheep. Start the car and go look at the HB above that rpm range and see if its wobbling. If that is you problem then do you self a favor get an aftermarket one thats SFI approved and replace the seal behind the HB That should stop that leak.

CantStopTheFox...

What about ignition?

The reason I ask is that it now breaks up over 4k RPMs. Almost feels the same as when the rev limiter kicks in. Then it vibrates the whole car real bad as it decelerates down to 1k RPMs (Really rough ride...something broke somewhere).

But idles perfectly. NO vibration at normal idle (900RPMs)...or when I am able to get around and listen!?!

I had so many idle issues before I got the SCT Chip and a tune...could it be related to the tune?

-When I rev in neutral it vibrates and breaks up at high RPMs.

-I took off in 2nd gear and wound it all the way up to 5700......and it was breaking up at the top bad...big drop in torque....No way I was going to make it to 6000.

-Major vibration as I slow down to stop at a light...

Tune/Chip? Or maybe ignition issue? I have MSD6al with the 6k pin. Could it be off?

Or maybe plugs? When I tuned it, they were fouled pretty bad.....(had to replace them 9months ago). Could it be something as simple as that?


Appreciate your time guys...!