engine diagnostic experts....need help bad!

[jammy]

Ok, I am in need of some serious help here cuz I am stumped with this engine vibration (85 2.8) that I think has been there for quite a while. The vibration is apparent all across the rpm band but it expecially doesn't sound good when revving past 3000. You can even notice a distinguished shake to the car at idle (really noticeable in the dash pad, shifter and seat).

I recently noticed that the harmonic balancer was screwed as you could see it wobble so I thought that has to be it! NOpe......even though the rubber ring was half way out and the outer ring was definitely shifted off centre, not a bit of difference in the vibration :eek: The balancer wasn't new (from wreckers) but it looks great and now when spinning is completely true.

I checked the timing tonight and it was at about 20* (not sure how since I set it at 10 last fall) so I shifted it back to 10 and it ran even worse! There was a bad throttle delay and choking which made it hard to get it into 1st. So I put it back to where it was for now since it runs better.

Now I am stumped, what are some other problems that could lead to this vibration???? I am going to check compression, spark and vacuum tonight and will post what I find to see if that helps any. I have been told that V6's naturally have vibration but this just doesn't seem right to me I have put so much time into this car and now it is treating me like ****.

Can anyone help point me in the right direction?

greatly appreciated.

[chris the great]

if it vibrates, something isnt balanced...simple at that....or is it.

[jammy]

Originally posted by chris the great:
if it vibrates, something isnt balanced...simple at that....or is it.

WHat about ignition or fuel problems (cylinder not firing). That can result in the same thing can't it?

[saved1]

you could have a broken motor mount,or a cylinder not firing.

[Brian_D]

An out-of-ballance problem would not cause vibration at all RPM's. There would be some RPM value where it would get better, or disappear completely.

You're probably missing on one or more cylinders. With the car running, stat unplugging spark plug wires. When you pull one off, the car should stumble, then return to normal after replacing it. If you pull off a spark plug wire and can't tell the difference in how it's running, it wasn't firing in the first place.

Good luck!

-Brian

[silvachris1]

Ummm, I'm not too sure about trying that while the car is running, if it arcs over to you, it's gonna hurt like crap. Maybe take them loose before you start the car and just let them set on the plugs, then just pull em off with some rubber handled pliars. Just giving you some warning cause gettin shocked by a plug wire isn't fun.