So the car was running perfect all day and then I stop at the drive in to get some food and the engine light turns on. The idle starts bumping up and down like i'm tapping the accelerator and when I let out the clutch it hesitates. When I shift gears sometimes it will buck, this happens more often the less I rev the engine. I get back on base and get out and the muffler is put putting but the sound is a much deeper tone than when it was misfiring a month ago. Its also less frequent but still rhythmic. So then I turn the car off and back on again and everything is working fine but the CEL is still on. I drove it around for a bit and no more bucking or bouncing RPM's. Weird!

I dont have my tools with me otherwise I'd be checking the plugs, etc. So I was just wondering if you guys have any ideas? Maybe I'll just reset the ECU and see if it comes back.

 

Okay, so after restarting the car the problem seemed to go away. CEL was still on but since there were no symptoms I pulled the clock fuse to reset it. Car drove fine for about 3 days and then while I was driving around again the problem came back and the CEL came back on. Problem was exactly the same. When at idle, rpms bounce slightly. When giving slight gas the rpms bounce a little more, the bouncing gets stronger the longer I hold it. As soon as I give it a little more gas and get above around 2000 rpms, the bouncing stops.

So once this happened, I immediately stopped the car and restarted and the problem went away again leaving me very confused.

Some recent things I've done to my car:

Replaced clutch, flywheel.
Replaced short block.
Replaced timing belt, crank pulley, water pump.
Replaced rotor, cap, plugs and wires.
Valve job, replaced some bent valves.
Ignition switch recall.

I put about 600 miles on the engine after all this was done with no problems.

The only thing I changed right before the problem first occured was I added a quart of oil but this oil was a different brand than was already in the engine.

Any ideas?

 

Shameful bump, if you guys need any more information I can find out. Any help would be much appreciated.

 

sounds liek u have an h22 eh!? well most ppl with h22 has that problem, ppl narrowed teh problem down to Knock sensor, or teh EGR valve. but most ppl are saying its teh knock sensor, and they fixed this problem by getting a p28(being it doesnt have a knack sensor board) and get it chipped and tuned with the h22's basemap.

theres a huge thread goin on about this. search its called 3K hesitation.

 

This is all pointless. What is the code?