I'll try to be specific as possible on my issue. The car is running rough. It runs great when cold (rich?) even being able to get moderately hard acceleration without misfires. Once it warms up it has a hiccup at idle, you have to "clear its throat" riding the clutch to get moving, or the engine will stumble when accelerating from a stop. If you mash the throttle at any speed, it drops a cylinder, but doesn't always seem to be the same one. Doesn't like to accelerate under heavy load without misfiring. When accelerating and it misfires, you can back of the throttle until it picks up the misfiring cylinder
Everything is stock. The engine has 262k on the odo. Rebuilt after the classic failure at 162k. The car sat for about 10 months. To my knowledge the car was running fine when I parked it. At the time of being parked it did have codes P0456 and P0442 (evap codes).
When I got the car out of storage the alternator was seized, so I replaced it.
The engine seemed to be running fine at idle and acceleration, but if you pulled over 5500rpm it would misfire. The high rpm misfires progressed to becoming rough idle and misfires under acceleration. I assumed the evap leak could be contributing. Being unable to find the evap leaks I had my shop put it under a smoke test and found leaks in the gas cap and purge valve. Replaced both. Codes have not reappeared in 2 months time. I assume I have fixed this problem.
I am still getting P0301, P0303 and P0300 codes. Since it was still running rough and the engine has a habit of eating aftermarket MAF sensors, I swapped it for new (sensor under warranty). No change.
The issue seems to be an air/fuel mixture problem, and the car sat for awhile, I put in fuel injector cleaner and dry gas. The engine runs much better when there is fuel injector cleaner in the tank. (changes octane?) With fuel injector cleaner in the tank the st and LF fuel trims are within 2% lean/rich. If I force it to misfire continuously, the short terms will go about 15-20% lean. Which makes sense I guess since a lot of raw fuel is being dumped in the engine. Without fuel injector cleaner I was getting the blinking CEL.
I couldn't remember the last time I had changed the plugs, (probably when I rebuilt the engine at 162K) so I threw in a new set. The idle only has occasional misfires, acceleration problems persist, but at a higher engine load. When I pulled the plugs, gaps were pretty large (didn't have tool to measure at the time) the outer area was carboned, but the central ceramic cone was bright white looking lean. (see misfires/STFTRM).
I inspected air plenum, but haven't found any tears, (I would have expected them to leak during the smoke test if they existed). I haven't pulled the injectors yet, and I don't have a way to measure fuel pressure.
HELP! Suggestions?
Everything is stock. The engine has 262k on the odo. Rebuilt after the classic failure at 162k. The car sat for about 10 months. To my knowledge the car was running fine when I parked it. At the time of being parked it did have codes P0456 and P0442 (evap codes).
When I got the car out of storage the alternator was seized, so I replaced it.
The engine seemed to be running fine at idle and acceleration, but if you pulled over 5500rpm it would misfire. The high rpm misfires progressed to becoming rough idle and misfires under acceleration. I assumed the evap leak could be contributing. Being unable to find the evap leaks I had my shop put it under a smoke test and found leaks in the gas cap and purge valve. Replaced both. Codes have not reappeared in 2 months time. I assume I have fixed this problem.
I am still getting P0301, P0303 and P0300 codes. Since it was still running rough and the engine has a habit of eating aftermarket MAF sensors, I swapped it for new (sensor under warranty). No change.
The issue seems to be an air/fuel mixture problem, and the car sat for awhile, I put in fuel injector cleaner and dry gas. The engine runs much better when there is fuel injector cleaner in the tank. (changes octane?) With fuel injector cleaner in the tank the st and LF fuel trims are within 2% lean/rich. If I force it to misfire continuously, the short terms will go about 15-20% lean. Which makes sense I guess since a lot of raw fuel is being dumped in the engine. Without fuel injector cleaner I was getting the blinking CEL.
I couldn't remember the last time I had changed the plugs, (probably when I rebuilt the engine at 162K) so I threw in a new set. The idle only has occasional misfires, acceleration problems persist, but at a higher engine load. When I pulled the plugs, gaps were pretty large (didn't have tool to measure at the time) the outer area was carboned, but the central ceramic cone was bright white looking lean. (see misfires/STFTRM).
I inspected air plenum, but haven't found any tears, (I would have expected them to leak during the smoke test if they existed). I haven't pulled the injectors yet, and I don't have a way to measure fuel pressure.
HELP! Suggestions?