Ignition Problems

[Parker]

Hi Sau brains trust

My 32 GTR has recently developed some troublesome ignition related problems and i am hoping someone here with more knowledge than me can help shed some light on the problem.

It all started about 5 months ago when i went to start the car one afternoon and found it had dropped a cylinder. On inspection the 3rd spark plug from the front was very dirty and assumed that the coil pack had given up the ghost. A friend had a set of splitfires available so i grabbed them and also replaced the plugs with a set of pfr (or is it prf?) 7 platinum plugs.

All was well until last week when upon returning from 4 weeks away (the car was started and run until warm every weekend whilst i was away) the car had once again dropped a cyllinder. Once again the 3rd spark plug from the front of the engine was fouled but the 4th one was also quite dirty (the rest were perfect). As i needed to use the car i cleaned both plugs and changed their position in the engine so if #3 or 4 fouled again i'd know it wasn't just a dodgy spark plug to blame.

50km later and dropping another cylinder i find that only #4 is fouled and #3 is pristine along with all the other plugs.

Seeing as the position of the fouled plug wasn't consistent i have decided to try a set of 6 platinum plugs incase the 7's were just fouling up because of too much time spent idling and not getting thrashed (i understand they are a 'colder' plug?). I've now been driving without incident for 100k's and the 6's seem to be working much better. I am however noticing more hesitation and missfires than before my troubles started last week.

Both set of plugs were gapped to .75mm.

The car has:

Rebuilt engine (forged internals)

N1 water and oil pumps

R34n1 turbos

PFC Djetro

Sard 700cc injectors

and the usual boost controller/exhaust/pods etc with about 360rwhp

I have also cleaned and inspected the earths on the ignition module and the bolt holding the coil packs down at the rear of the engine. The only things i can think of left to try is another ingition module and/or loom that goes from the ignitor to the coil packs.

Can anyone help with some suggestions before i go running to my workshop?

Cheers.

[R31Nismoid]

Ok, so 260rwkw though R34 N1's... your only running around 1bar, or less.

So your not really pushing the setup by any means.

Hmm.. IMO - The gap is too short on the plugs for a start.

The most i would be gapping down to is .8 and thats it.

If you need to go further you have ignition problems especially if you have new coil packs in there already

I would check the coil packs, they might not have a great connection.. ie. the connections might have corrosion or a wire that might not be set in correctly or something like that which is a pain in the ass to find, but causes these niggling problems.

So check the connections and the loom for anything that might not be right

See how that goes and let us know... all i can offer at the moment

[Parker]

Thanks nismoid,

the 360rwhp is with about 19psi. I say about 19psi because i have had some weird boost control problems that looks like being caused by the standard wastegates not being able to control that much boost. (peaking at 19 and then dropping to 15-16 and then fluctuating between 15 and 17psi)

I've had quite a few thorough looks at the loom and the connections to the coils themselves and haven't been able to find anything amiss. But as you say these sort of niggles can be a tail chasing exercise to sort out.

[Parker]

P.S. i only run stock boost pressure normally.

[R31Nismoid]

So was 360rwhp on what boost level?

Sounds like you need a better boost controller for that problem as no-one else has issue with the internal gates, infact people are making over 400rwhp no problem at all

Hrm... what else would cause it... 32GTR's have the black ignitor box dont they?

Also, not a fan of platinums... once they are fouled, thats it. So they are a waste where coppers dont cost much at all.

Maybe try a set of coppers and see what happens?

Not sure... just throwing you some cheap ideas that you can DIY

[Parker]

Cheers,

360rwhp was at a peak boost pressure of 19psi (but after the initial spike it was only about 17psi max).

I have the blitz dual solenoid boost controller (spec R) and it was purchased and installed new earlier this year. i know of quite a few of these boost controllers working well on GTR's over here in the west so i'm assuming my boost control problems aren't to do with the ebc.

I've now done about 200K's on the 6 plugs and still haven't dropped a cylinder but there are definate ignition quirks when the engine is hot and most frequently this is at light throttle applications.

Edited October 27, 2006 by Parker

[Parker]

OK just for a bit of an update.

After doing about 200k's on the 6 range platinum plugs i took the car for a run down south (about a 230k trip each way) On the way down the car was perfect until up to operating temp and from then on whilst driving the car would occasionally missfire. The miss was almost always when doing a consistent speed and not bad enough to really worry about. For example at 110kph you'd feel the slight stumble every few minutes.

The car sat overnight and the next day and then was driven home again where, suprise suprise, the car performed faultlessly and has continued to do so since.

So my question is:

Could the fuel sitting in the tank for the 4 weeks when i was away somehow have gone bad and caused my ignition problems or is it still likely to be a gremlin somewhere in the electrical system? I have left the same vehicle for up to 6 weeks when i have been away in the past and not had a similar problem. I only ever use BP ultimate.

Cheers.