dead cylinder...Extremely frustrated!

[mikey719]

Alright, well my N/A started to miss slightly at idle about a month ago, not horrible, but annoying, i noticed the spark looked a little weak, so i replaced the coil pack and the miss continued, did the normal stuff, cleaned maf, ohm tested the injectors and all that fun stuff, but found no problems. Today I was driving to my friends house to have him look at it, and that cylinder started cutting out, then completely stopped firing all together. I replaced the plug, swapped coil packs, tested injector (12.6) and its still completely dead. The old plug looks fine, no build up, nothing out of the ordinary. Another thing that may help, is when i first start it, it will fire for maybe 5 seconds before it stops. I pulled the radiator cap, no bubbles, the cylinders next to it are all firing perfect, so that makes me doubt head gasket. Usually when i've had similar problems, I would get a strong smell from the unburnt fuel, but i noticed theres no smell, and the plug didnt seem wet when i took it out. I spun the CAS and the injector clicked but I'm wondering if they can get clogged to the point where they can kill a cylinder, and still test out? Any help would be appriciated, this is my DD and need to get back and forth to work!

[bartZ32tt]

Don't waste any more time/money - get a compression and/or cylinder leak down test done. Been there, done that

[300ZXttZMAN]

+1^

You must remember, 3 things are needed for an internal combustion engine to run. Spark, fuel, and compression. You have fuel and spark you might not have compression.

Test the compression and get back to us.

Oh and welcome to NICO!

[nissanfreak12]

Alright, well my N/A started to miss slightly at idle about a month ago, not horrible, but annoying, i noticed the spark looked a little weak, so i replaced the coil pack and the miss continued, did the normal stuff, cleaned maf, ohm tested the injectors and all that fun stuff, but found no problems. Today I was driving to my friends house to have him look at it, and that cylinder started cutting out, then completely stopped firing all together. I replaced the plug, swapped coil packs, tested injector (12.6) and its still completely dead. The old plug looks fine, no build up, nothing out of the ordinary. Another thing that may help, is when i first start it, it will fire for maybe 5 seconds before it stops. I pulled the radiator cap, no bubbles, the cylinders next to it are all firing perfect, so that makes me doubt head gasket. Usually when i've had similar problems, I would get a strong smell from the unburnt fuel, but i noticed theres no smell, and the plug didnt seem wet when i took it out. I spun the CAS and the injector clicked but I'm wondering if they can get clogged to the point where they can kill a cylinder, and still test out? Any help would be appriciated, this is my DD and need to get back and forth to work!

After you do a compression test, re-look at that injector.

Im not sure if you have the newer or older style injector, but I had an interesting thing happen to me with a dead cylinder. After I got to Denver, my car started to get a miss. Before I moved I bought newer style injectors and the car ran great on the drive here. Well when I started to miss, I assumed injector. Tested the injector and it tested fine, clicked, everything. So I just passed that up, did a compression test, leak down, boost leak(which I found some leaks), every test I could think of. Still had a miss, so one day after ready to just give up on it, I decided to swap injectors, the miss followed. So I sent back the injector to ConceptZ, he calls me and say it flows fine and test good. So I told him my scenario, he sent me a new injector, everything has been good since.

It could be worth a shot if your compression comes out good or not. I just about sold the car cause my first three readings on the test had shown the compression was bad, but in all the cylinders, not just the one. So I knew something was up, after I got the injector fixed, retested the compression, a couple more times, all shown comp at 155. It was worth the extra work.

[Z-owned]

The injector have corrosion on the pins? could be testing fine with the plug pulled on it And the corrosion could be in the plug making for a bad contact when plugged in. Also check the wires to see if they look ok around the plug

[mikey719]

Thanks for the replys! I know compression can kill a cylinder, but the one thing that is kind of making me lean away from it being a compression problem, (still testing it later today) is that in the past when i had cars with compression problems, the cylinder would misfire until the rpms got higher, which i am assuming is because there is not enough time for the amount of blow by you can get at idle. but i guess if it was a head problem that wouldnt matter.

[mikey719]

Or a more likely problem is that i'm in compression problem denial....

[bartZ32tt]

Thanks for the replys! I know compression can kill a cylinder, but the one thing that is kind of making me lean away from it being a compression problem, (still testing it later today) is that in the past when i had cars with compression problems, the cylinder would misfire until the rpms got higher, which i am assuming is because there is not enough time for the amount of blow by you can get at idle. but i guess if it was a head problem that wouldnt matter.

I speculate that it would only appear to go away at higher rpm due to more engine noise - a misfire is less apparent with more engine noise. A dropped cylinder would not come back with higher engine rpm. Let us know how the test goes - hope to hear good news.

[mikey719]

Compression tested out fine...the only thing I can think of is clogged injector, any other ideas on what it could be?

[mikey719]

The dead cylinder is the middle cylinder on the drivers side, and it seems like you could get the injector out inbetween the plenium. does anyone know if it is possible? I have never pulled the plenium, and the only time i have to work on it as at night, in my driveway, not the ideal conditions for things ive never done before... is there any trick to figuring out if the injector is spraying fuel with the injector installed? like i said, i already checked the plug and it looked dry

[Ace2cool]

You can pull it out, but you have to dremel into the plenum near the injector to get enough vertical clearance to remove it. IF it comes out without needing a vise. Most of us have to use homemade tools to press the injectors out of the rail, which is why it's usually easier to just pull the plenum.

[mikey719]

well, i cleaned off the corrosion from the plugs, and put new batteries in the multimeter and now its reading at 37 ohms! My only worry now is that when I put the new injector in (hopefully tomorrow if i can find one) that it still will miss. To me it seems like if anything, an injector would cause a miss at higher rpms rather than at idle, since it would demand more out of it. Mine seemed to go away once you pressed the gas, but maybe it just became less noticable?

[Ace2cool]

A misfire becomes less apparent at higher RPM's due to the faster rotation (inertia) and more engine noise.

[mikey719]

well finally replaced the injector, runs beautiful, it missed twice in the first five minutes, after it was sitting for 5 days and cold, once it warmed up, didnt miss at all. thanks for all the help!

[Ace2cool]

No problem. That's what we're here for. Thanks for sharing your solution for future searchers.