Seriously doing my head in....Can alternator cause misfire?

Thanks Dave, the engine is still being run in, so I'm still using running in oil. I'll check the voltages as per your recommendation. The issue is always there hot or cold, it's just much worse when the engine is cold.

 

Yes we tried this at the tech day but its like the fault is dynamic....we couldn't pin it down to a particular cylinder by way of injectors or coil pack connectors/wiring. It just seems to roam around the cylinders.

 

It could be o2 sensors as i had this problem on my NA, went to the trouble of replacing everything under the sun then said nahhh cant be o2 so i left them for another 6 months. I then changed them to BRAND NEW ones and reset the computer and disconnected battery and whatever else i could think of, even monitored it on conzult and it said they were fine. I ended up just disconnecting them and leaving the plugs hanging and that fixed it completely although i could not understand why even with new ones it was playing up. Disconnect your o2s and see what happens, I think it will fix it!

 

Timing looks to be ok.

 

Radical idea, but hey I'm willing to try anything. At least it might point me to where the issue is located. I'll try this after checking the alternator since its a quick easy one to do.

 

regarding misfire being dynamic?
If you run Consult during driving (passenger of course) and when the car is misbehaving (under early load) have U tried 2 switch off each plug in turn to see if its not as dynamic as thought when stationary.
Could it have anything to do with earthing current (bleeding voltage) at low revs but as revs increase power is sufficient to provide the right (enough) charge .. could check wires in fusebox near power steer for exposure?
Admittedly may be off planet with these suggestions?
good luck

 

Thanks coolum. Like I said....at this stage I'm considering any suggestions. I'll add it to my list.

 

Background

Can you give us a little more background. Did this problem just start to occur or was there some work done on the car / engine and the problem started afterwards. I'm leaning towards some sort of electrical fault. But have you checked fuel pressure? What do the plugs look like? Can you pick a cylinder thats not working as hard as the others from discoloration? How about a full buzz out of the engine loom. Good luck.. Sounds like this thing is driving you nuts.

 

So what

I've had this car for two years and it's only been running properly for probably one week during that time.

ever problems the car has had before the re-rebuild, are not related to the current problem, or has something similar existed all the time you've owned it?

 

seriously thats why I let mine go, mitch the guru tried to fix it but it was too unreliable missed too many events, went to skyline problems over just fill her up and change race rubber, purrs like a kitten and bits like a rattle snack

 

Bought the car 2 years ago with blown motor. Got recondition stock motor and turbos put in her. I have been unlucky enough to have one failure after the next, often with similar symptoms. First I had a short in the ECU, found and replaced ECU. Fixed and went great for a week then new problem. Found dead coil pack, replaced and went great for a week. Injector failed, plenum pull, replaced injectors went great for a week. And now this one. Believe it or not, I think there was almost no overlap with any of these problems as between each failure the car pulled like a car does with a new motor and turbos.....beautifully. It has always been so short lived though. I haven't checked the fuel pressure, but I have replace pump and symptoms don't suggest fuel pressure problem. When I pull the plugs they are clean. None of them are black and that another reason I'm starting to think it's not a particular cylinder that is the problem, but more an electrical fault elsewhere. And yes it's driving me crazy, I just want to be able to drive the bl00dy thing!! The new motor has only travelled 1500km in 2 years because its always off the road. Cant seem to keep it on the road long enough to run the dam thing in :bash:

 

I bought the car with a blown motor so don't know what it was like before, but each failure has clearly been a new issue.

 

But you know what. This is the third Z32 I've had and the other two were great. The last one I drove every day for 5 years and it hardly ever missed a beat. It really is the luck of the draw. You are probably correct in saying though, that the Skylines are going to be more reliable than the Z's.

 

I know it's a Skyline, but does it really have "bits like a Rattle Snack"???:rofl::rofl::br:

 

Earth problems?

try puting some more earthing points around the motor. I over earthed mine because I heard they were notoriously bed for earth probs. Just a sugestion as it could be bad earthing between motor and body/chassis.
hope this helps, Andy

 

Lot's of good suggestions.

I think the key here is temperature.

Does our ECU do anything different during warmup? (especially timing related)
For example, I can't engage OD until my Z is at operating temps.

Though, with this said it could be indirectly linked to temps, like a bad earth that comes good due to heat expansion.
Or even a boost leak that does the same thing. (but doubt this as it would have to be a pretty damn big leak)

Hope you sort it soon, would be doing my head in trying to figure it out.

Good luck,

Egg

 

Thanks Andy, I'll look at the earths after I check the alternator.

 

Voltage Results

Ok so here are the voltage readings:

Ignition on only: 12.1V
Engine Idling: 14.0V
3000rpm: 14.2V

Does this means the alternator gets a clean bill of health, or can there still be an issue with it?

 

With those voltages, yes the alternator is doing its job. do they vary much? whats the range (min-max)....