I was on a 6 day road trip, and developed an engine problem. The car was running great - smooth, even, good mileage, not even warm. We came down out of the mountain pass, and parked in a small town for lunch. After lunch, I got back on the roadway. When I hit the gas to get into traffic, suddenly things changed.
The engine developed a significant vibration, and ran poorly. I pulled over when I could, and checked things out. It had a significant engine vibration around 2300 rpm's, and would not run well at all above that - popping and cracking.
It was clearly missing on one cylinder, and We tracked it down to cylinder #3 by unplugging injectors. Spark is great - a good 1" bright blue spark. After messing with the injector plug, I got that cylinder to work again. So it's a bad injector that needs to be replaced, or a bad harness.
BUT.... the vibration remained. it started around 2300, and fades off around 2700. Anything above or below that and it runs great - smooth, even, sounds good, and decent fuel economy. But, the vibration is significant.
These are the things I tried in the hotel parking lot that did not help:
-- Removing the fan belt
-- Tightened the balancr bolt
-- tightened the pulley bolts
-- swapping spark plugs
-- checked the ohms on the cables
-- Swapped injector plugs/wires (batch fired).
-- Checked compression - finger test only, it was getting some compression
-- visually inspected all the springs and valve train
-- Adjusting the clutch cable.
It is clearly engine related. It's easily reproducable in the parking lot. If I run the car up to 3,500 rpm's, push in the clutch and let it roll, it resolves. It's rpm related.
Doesn't matter what gear it's in, and is not affected by clutch actuation.
So, I drove the car, just kept it out of that magic rpm range. Sometime that was tough to do. But it continued to run well for the next few days.
On Friday morning, the engine started but was rough. Would run well at all. Pulled 1 through 4 plugs, and they were fuel fouled. Cleaned them up, and got the car going again. Once it warmed up, it ran great again - smooth, even, good gas mileage, no hiccups.
Except for that continued and unchanged vibration.
When I got home, I did a compression check, and all cylinders were almost exactly the same. Exscept for one that was a bit higher than the others.
Then I pulled the right head off. The head, block and pistons looked fine, except for being rich. Plugs were fouled like it was running rich. The O2 sensor is in the right bank, and was reading a steady 14.0-14.5.
Pulled the motor out, and inspected the clutch assembly. This is my Centerforce clutch, that's been in the car only 3 years; <15K miles.
3 bolt holes showed cracks like this one:
and this looks pretty bad.
And here you can see that the weights are waaaaay off center.
The clutch disc and flywheel look great.
I will replace this clutch hat with another Centerforce - only because I have it sitting here on the shelf. But when I overhaul the engine this winter, I'll install something else. Probably a Spec 3, or maybe a Ram HD.
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Centerforce Pressure Plate failed
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