HELP , misfire issue r32 gtr

[bakerman1978]

hello I am having a misfire issue when the car gets hot ,however it runs great when cold will misfire as soon as it gets hot, cylinder 4 fails then sometimes it will be fine again I just put new plugs in but it was also doing this with the old ones I checked the coil pack and I still get spark, it seems that it may be the injector or injector plug cause when I push on it hard while engine running it seems to come back on ( cylinder 4), I checked theat plug and it is a little wet and then i checked cylinder 3's plug and it is dry and white but clean from what I understand a white plug indicates running lean however as soon as it drops from 6 to 5 cylinders all you can smell is gas so wouldn't that be running rich, so is there a way to tell if it is the injector or plug itself without pulling the injectors out , also I am missing 2 exhaust studs and the car holds boost steady at 14psi and my vacum is at -15 also my speedo is behind (slow) which is also a new problem basically I'm just looking for any feedback before I start spending money for parts that I may not need thanks

[xcye]

I'd do the following in your case.
0. Swap spark plug. (Faulty spark plug?)
1. Swap Coilpack with a known good one. (Faulty coil?)
2. Swap ignitor with a known good one. (Faulty ignitor?)
3. Check ignition wire with for cylinder 4. (Faulty ignition wiring?)
4. Check ECU for error code. (Faulty ECU or wiring?)
5. Check compression for cylinder 4. (Low compression?)
6. Swap injector with a known good one for cylinder 4. (Sticky injector?)

[hp44incgtr]

had the same problem i fix it by changing the coils and also coil wire car is dinosaur old thems wires get hot like crazy where they sit in the engine, hard to tell by eyes but i bet if u open the insulation some of this wire are for sure green.. HAS FOR the dead cylinder most def an connection problem make sure the injector plug clip nicely in with the locking pin..

[bakerman1978]

had the same problem i fix it by changing the coils and also coil wire car is dinosaur old thems wires get hot like crazy where they sit in the engine, hard to tell by eyes but i bet if u open the insulation some of this wire are for sure green.. HAS FOR the dead cylinder most def an connection problem make sure the injector plug clip nicely in with the locking pin..

thanks that is what I thought my coil wires were replaced last year with other used ones but I will start with the coil pack and hope it's that, thanks hp44incgtr and xcye

just a side note after i drove it yesterday I tried pushing down on the injector plug wire and the cylinder would't come back on
and also could the coil still provide spark even if it's faulty thanks

[quadracer111]

Did you gap your plugs properly? I had same issue with my mkiv supra and my r32 when I first got them, turned out previous owners gapped the plugs wrong. At first I thought it was coils. Glad I didn't drop $400+ on new ones.

[bakerman1978]

yeah I gapped them at .8 mm and it was doing it for about a week before I changed the plugs

Did you gap your plugs properly? I had same issue with my mkiv supra and my r32 when I first got them, turned out previous owners gapped the plugs wrong. At first I thought it was coils. Glad I didn't drop $400+ on new ones.

[Nvdgtr]

Im having the same issue and have done the following and still no luck for me.

-delete cat, new test pipe
-new plugs gapped at .8mm
-changed igniter with a told working one
-new coil pack harness
-compression is 162 across
-briefly tested for vac leaks
-reset ecu
-assured maf are plugged in
-looked at intercooler and bov pipes and all seems to be intact, didnt check very good as car wasnt jacked up or anything so..
-assured the grounds a good

today i started my car was running fine (bc it was cold still) switched the ignitor an it started misfiring on cyl 5. i then put my igniter back on and it was good. i drove the car around for about 10 min and it got warm and started misfiring again but this time on cyl 2. i switched back the other igniter and then the misfire was back to cyl 5...

i think my next step according to the research i have done is to:
-clean/check the MAF
-check the 02 sensor. i was told if i start car, (while its misfiring) unplug 02 sensor, if the car started running worse, then the 02 sen is/should be good still. if theres no change then the 02 sen is bad or on its way out.. I'm not 100% sure on this (maybe anyone else can confirm?)

ill update this thread with what i have done to locate my issue n maybe it will help you in a way. gl!

[bakerman1978]

yeah i just swapped my coils and it's still cylinder 4 that goes out so I'm wondering if the injector or injector wiring could fail under high heat but I think I might clean my mafs next and see if that makes a difference ahh the joys of being a skyline owner it always gives you something to do

Im having the same issue and have done the following and still no luck for me.

-delete cat, new test pipe
-new plugs gapped at .8mm
-changed igniter with a told working one
-new coil pack harness
-compression is 162 across
-briefly tested for vac leaks
-reset ecu
-assured maf are plugged in
-looked at intercooler and bov pipes and all seems to be intact, didnt check very good as car wasnt jacked up or anything so..
-assured the grounds a good

today i started my car was running fine (bc it was cold still) switched the ignitor an it started misfiring on cyl 5. i then put my igniter back on and it was good. i drove the car around for about 10 min and it got warm and started misfiring again but this time on cyl 2. i switched back the other igniter and then the misfire was back to cyl 5...

i think my next step according to the research i have done is to:
-clean/check the MAF
-check the 02 sensor. i was told if i start car, (while its misfiring) unplug 02 sensor, if the car started running worse, then the 02 sen is/should be good still. if theres no change then the 02 sen is bad or on its way out.. I'm not 100% sure on this (maybe anyone else can confirm?)

ill update this thread with what i have done to locate my issue n maybe it will help you in a way. gl!

[Nvdgtr]

Have you swapped the coil pack itself or the harness?

[bakerman1978]

the coil pack itself

[AL91GTR]

I went through the exact same issues and tried a new coil pack harness, tested the ignitor, installed new plugs gapped at 0.8 and basically exactly what you describe.

My car has 125 K on the odo. From what I have read the factory coils are generally good for about 100k. So, check your coils. Run the resistance on them and if it is out of whack than likely they are on their way out and causing issues once they warm up. I believe factory resistance is suposed to be 0.6 - 0.9 ohms and mine all reading 1.2 across the board.

I put in new LS2 coils with a ToroGTS harness and new plug wires and got rid of that 22 year old POS ignitor and my car runs so smooth now that when i'm idling at a stop i quite literally cannot feel the car running. It is so smooth and no misfire, hesitation or anything. IMHO better than spending more $$ on new coils and still having the old ignitor in there.

[xcye]

Have you swapped a good ignitor and checked the ignition harness yet?

[Skym]

What can cause missing -

Coilpacks (coilpacks are damaged due to wide sparkplug gap, incorrect heatrange and engine can randomly run on 5 cylinders and then eventually always run on 5 cylinders, usually 2x coilpacks fail and rest are ok, but best to replace all 6 coilpacks if sparkplugs weren't gapped down and engine missed at higher rpm)

Coilpack loom (due to age and if stiff as a ironing board, replace it)

Ignition module (engine would stall after 10 minutes of driving and won't be able to start it for another 10 minutes due to ignition module has to cool down). But can cause some cylinders to not fire (rare but does happen).

Injector loom (due to age and if stiff as a ironing board, replace it)

CAS (bearings inside fail due to age, engine hard to start when cold, hot, eventually engine starts randomly stalling, rough idle). Sometimes incorrectly set CAS can cause missing.

Also Skylines can missfire at idle due to o2 sensor making engine go lean (lean missfire). If unplug o2 sensor x2, start engine it should idle smooth. If this is the problem, then ECU retune is needed to correct this. This is a common problem on many modified Skylines without retuning ECU.

MAF's can make ECU make engine stutter if there's a intake airleak just after MAF'S (similar to coilpack failure and often can be mistaken for coilpack failure).

Intake leak before MAF can make MAF max out and hit boost cut (fuel cut) on ECU (if have clamp onto adaptor type of airfilters infront of MAF's. Fit Apexi or similar podfilters that bolt onto MAF's to fix this problem).

Injectors can start leaking, which makes engine seem like it's misfiring.

Intake manifold gasket's can blow (common on GTS, GTR) which can make rpm go up and down (due to o2 sensor making ECU make engine go lean, rich) causing a rough idle. Engine running leaner, into 17's should give it away.

Too thick oil for engine, which makes engine struggle to idle, sluggish response, etc.

[bakerman1978]

sounds like a good idea however what am I looking at for cost for all that

I went through the exact same issues and tried a new coil pack harness, tested the ignitor, installed new plugs gapped at 0.8 and basically exactly what you describe.

My car has 125 K on the odo. From what I have read the factory coils are generally good for about 100k. So, check your coils. Run the resistance on them and if it is out of whack than likely they are on their way out and causing issues once they warm up. I believe factory resistance is suposed to be 0.6 - 0.9 ohms and mine all reading 1.2 across the board.

I put in new LS2 coils with a ToroGTS harness and new plug wires and got rid of that 22 year old POS ignitor and my car runs so smooth now that when i'm idling at a stop i quite literally cannot feel the car running. It is so smooth and no misfire, hesitation or anything. IMHO better than spending more $$ on new coils and still having the old ignitor in there.

[bakerman1978]

no I don't have anyone around me with a gtr to swap with

Have you swapped a good ignitor and checked the ignition harness yet?