AE92 Engine Vibration - Misfire?

[JKD]

Hi all,

I developed a strange issue with my 1992 Geo Prizm (AE92 w/ 4AFE) today. I have had this daily beater for about 8 years now.

Problem:

I drove the car this morning 20 miles one way and everything was perfect. When I got back in the car to drive it this afternoon, the car sounded very strange. Upon driving the car, it vibrates terrible at low rpms. With the engine idling, I can visually see the engine moving. It almost feels like a misfire of some sort. The problem is amplified at low rpms and under a load (pulling a hill). I'm certain it is not the motor mounts because the noise is conveyed through the exhaust with or without a load.

I took a peak at the crank pulley and did not see any type of wobbling which may rule out the harmonic balancer. I also combed through the vacumn hoses and did not see anything that caught my attention.

I put new a new fuel filter, plugs, wires, cap, and rotor on the car around 10k miles ago so I do not think that the problem is ignition related.

Anyone have any ideas?

Thanks in advance

[90 GP]

It could still be ignition related as in ignition coil or igniter (both located under distributor cap). Do a compression check to see if have a cylinder with low compression.