Car running on 5 cylinders

[KornFlakeZ]

So basically my 90 n/a started running on 5 cylinders. The cylinder thats giving me problems is cylinder 4. I checked injectors, spark plugs, coil pack, wiring and they all seem to be fine. I also checked the PTU harness since its known for them to come loose and it seemed fine. I dont know where to go from here... i will probably check ecu codes and see if i get anything... any ideas of what could be causing the problem?

[t.mcginley.jr]

What did you do to check the injector? Did you swap out a known good coil pack into that cylinder? The PTU itself could be shot. Check for error codes and post back. How many miles on the engine?

[KornFlakeZ]

basically for the injector i used the screwdriver method to hear it working. yes i did swap it out for a known good coilpack to test it and that didnt work either... havent checked the ecu codes. gonna do that now... i suspect it could be the ptu since its the older ones prone to failure. the engine has about 108,000 miles on it.

[KornFlakeZ]

ok so the ecu gave me code 33 which means its an o2 sensor but, thats because the car has been running rich on the drivers side the o2 sensor crapped out... im getting kinda pissed right about now... im going to see if i can find a known good ptu so i can swap em and see if it makes any difference... any suggestions?

[t.mcginley.jr]

Did you do the power balance test where you leave the car idle and pull one coil pack connector at a time to see if they all drop the idle? You should definitely get a new PTU anyway and see if that helps. The o2 sensor is probably shot from running rich like you said. So either an injector is shot and/or stuck open making it run rich, or the PTU is toast

[GerryO]

Ohm checking all six injectors could prove helpful.

[KornFlakeZ]

yes i did do a power balance test and the only cylinder thats not working is cylinder 4. i checked injector 4 with the screwdriver and heard the twak twak sound that corresponds to a good injector but did not ohm test them... probably gonna do that next. im going to look around my area and see if i can find a known good ptu i can borrow for testing purposes and see if that fixes the problem. any other ideas? this problem just popped up overnight and its very frustrating >:(

[t.mcginley.jr]

Do you still have the old style PTU? or a newer post-93' one? The old style one is more boxy and has an aluminum front. The newer style is smaller and all plastic. Electrical items like this can just blow overnight so it really could be the issue. After testing with a good one then go from there. Btw what did the spark plug from that cylinder look like?

[KornFlakeZ]

it was all wet which corresponds that its running rich. i swapped spark plugs from a known good cylinder and it still didnt work... yes its the older style ptu with an aluminum front. is the recall that nissan made on these PTU still active? cause im thinking on going to a nissan dealer an checking out if i can get it swapped with a new style PTU... if not well im pretty much screwed since im outta cash and new ones on z1 cost about $220 dollars including the wiring harness adapter for old style harness...

[t.mcginley.jr]

Yes the recall is still active I believe. I know I read a post somewhere where a guy got his done under recall just last year. If you just call up the dealership and give them the VIN number for your car, they should be able to tell you whether or not it's eligible. Most likely it is if you still have the stock PTU. If for some reason they won't do it, you can always buy a used newer style PTU and harness from ebay and solder it in. It's a pretty straight forward process as far as I can tell. I'll be doing the same thing soon to mine

[KornFlakeZ]

nice! well i guess i will be giving them a call tomorrow and see if im eligible! ( crosses fingers in hopes that i am ).
i will update as work on the issue!

[t.mcginley.jr]

sounds good!