engine only running on 3 cylinders?

[S13FASTBACKSR]

I'm not sure if my engine is running on 3 cylinders or 4. From the sound of it, it seems like only 3. I know though that cyl. #2 is running rich because every time I pull out the spark plug its quite a bit blacker than it should be. All other spark plugs are fine. So what I did was swap #1 and #2 coil packs and that didnt fix anything. Then I swapped #1 and #2 spark plugs and thats didnt fix anything either. I bought a new fuel injector for #2 and swapped in a different ignitor and yet still nothing. The compression test checked out fine 131-133 on all 4. So does this sound to you guys like my engine is running on 3 cyl.? any ideas? Thanks in advance

[ca18det_boy]

if you were swapping coil packs around then it would be obvious if one of them was bad. Since it didn't make any difference when you swapped them I would say that the coils are fine. If the ignitor was bad then your car wouldn't even run, if the injector was stuck either your plug wouldn't have anything on it except fuel or you would be blowing smoke from it running rich. So we're going to be looking for something else. Unfortunately I have no idea what since I'm not standing in front of the car.

[S13FASTBACKSR]

Yes I know we are looking for something else since none of those fixed the problem. My question was what is that something? any suggestions?

[srpowered240sx]

swap ecus with a friend, i just went through this too. it ended up being my ecu was frying injectors one at a time. also, to see it you are missing on a cyl, unplug the coil pack while it is idling. you will notice a diference if that cylinder is working. if no difference, cylinder is not firing.

[Dori Dori]

^that's what I was going to suggest.

Get back to us and tell us what's happening.

[S13FASTBACKSR]

before i buy another ecu does anyone else have any suggestions? just a little more info for you guys to give you a better understanding..the only problem im having is when accelerating anywhere from idle (800 rpm) to about 4,000 rpm. The car is very hesitant and you can clearly hear from the muffler that the engine is missing. If my ecu was bad, wouldnt I have more than just one problem with the car? thanks in advance
Modified by S13FASTBACK_SR20DETNESS at 2:48 PM 1/1/2006

[srpowered240sx]

not neccessicarily i had to scrap my last ecu because it killed injectors for some odd reason, it worked perfect otherwise. just every week or two, it would kill one, very weird. just keep troubleshooting, eventually you will find your problem.

[S13FASTBACKSR]

bump to the top for me...took off the panel to just check for loose wires around the ecu but all was fine. I found out though that i was running a 63 ecu but from what ive read using an automatic ecu should not cause any problems. I havent bought a new ecu yet i tried cleaning my tps and i put on a new adjustable fuel pressure regulator i had laying around. that did help a lot. now instead of hesitating and misfiring all the way to 4000rpm it only does it to about 2300. thats an improvement but i want to fix it completely so anymore suggestions before i get another ecu? thanks

[straightedge]

while the engine is running unplug an injector one by one and see if it makes a difference in the performance of the engine, if it does then the cylinder is fine, if it dosent that is the dead cylinder. otherwise id check your fuel filter as well, never hurts to check the easy stuff. should be able to blow through it one way with little resistance and not the other way. i would also check to see if you are getting voltage to both the injector and coilpacks