Doc Holiday

I need some serious help with this one....

There's a strange vibration that is only felt in the shifter and by putting my hand on the engine or exhaust pipes. I don't feel this vibration in the pedals or the steering wheel.

1) The car idles smooth, but has a vibration (like a cell phone) felt in the shifter with a random thumping pulse every second or two. I checked vacuum at idle and it's steady at 24" hg.

2) The vibration and random thump felt in the shifter while driving gets a bit more intense as load increases. It happens in all gears, at all speeds, as well as zero speed at idle.

3) When crusing at a steady speed (usually on the highway) The vibration will "sometimes" start to oscillate, or make like a wave feeling. It's the same constant vibration, but it gets more intense and then less intense every 2-3 seconds. This is the most puzzling to me, since nothing at 70+ mph is rotating every 2-3 seconds.


Things I have checked....

1) All exhaust mounts, clamps, pipes, clearances and bolts, including manifolds.
2) Pulleys with belt removed.
3) Engine vacuum at idle.
4) Pulled plug wires (one at a time) to verify missing cylinders.
5) Pulled fuel injector wires (one at a time) to verify missing cylinders.

PLstang

Is it visible when you watch the engine? Could you have a bad plug? It kind of sounds like a dead hole. Mine did that once and I found a plug that was bad when I pulled them.

GidyupGo

Engine harmonics. Could be the ballancer or any number of other components.

Doc Holiday

I have had this problem for about 6-8 months. It doesn't seem to be getting worse, but yes... I have pulled all 8 plugs about 6 weeks ago and they looked ok (off-white insulators with very slight tan colornear the tips).

When I pull the plug wires, one at a time while idling, I hear a distinct miss and it recovers a few seconds after plugging it back in.

I'm not ruling out a miss, but with no codes, and the plugs looking good, it's hard to say.

I have to ruleout anything past the flywheel, because it can be felt with the clutch pushed to the floor inneutral, although it's much fainter. Gets much more pronounced as load increases. The thumping or pulsing on top of the vibration gets really bad under heavy load and lowerRPM's.

GidyupGo

Since you vacum is steady, you can rule out plugs. Like I said before, could be many things but not valves or plugs. More like a bearing or the harmonic ballancer.

Doc Holiday

I checked the plugs a few weeks ago and they all looked ok (off-white with very slight tan color near the tips). I also checked the plug wires by pulling them one at a time while idling and got a distinct miss, then it recovered when I plugged them back in. I did the same with the injector clips.

Doc Holiday

I have the Steeda UDP's (balancer) and I put the stock one back on, and both do the same. I even sent the one I bought back to Steeda to check, and they said it was fine. I can't "see" the engine vibrating or shaking, but I can feel the same slight vibration at idle as I do in the shifter.

GidyupGo

Anything wrong with the valve train will show up on the vac guage. That's how we used to diagnose in the ole days. Check motor mounts.