Spark

[BIG K]

I have a r32 with a rb25 conversion and have just brought a new set of super spark coil packs and new plugs after i changed these it was only fireing on 5 cylinders number 4 wasnt working. I checked compression on all 6 and they were all round the 125 mark which is good, checked the wireing harness to the coil packs and it was ok wireing was very crap but still getting power to them all. Tested the coil packs and they are all good, tested the plugs and tryed a different set that was all good too. Im running the microtech ltx12s ecu in it..

What could be my problem? Anyone know what to replace or to try next

cheers

kyle

[blind_elk]

Standard investigative process, move items around, see if the problem follows.

What happens when you swap #4 coil pack with, say, #6? Which cylinder isn't working properly.

And what about swapping #4 spark plug with #6?

[QWK32]

as blind_elk has said, see if the problem to stays on cylinder 4 when you swap some coilpacks over. if it does, have a better look at the wiring and plug to that coil, there may be something you missed first time checking, and even if the electrical plug looks ok it could be broken down inside.

if that still checks out ok, look at the microtech, you said you have the LTX12S, would i be correct in saying this model has built in ignitors? maybe the ignitor for cylinder 4 is fried?

[BIG K]

Ive tried swapping plugs and coild around and nothing changes. I have been told about that ecu and the igniters, a mechanic up here said that could possibly be the problem. If so and i need a new ecu what would be my best option as to what to get? Everyone says something different but what do other skyline owners think?

cheers

[QWK32]

pull the coil pack out, leave it plugged in, put a spark plug in it, earth the body of the spark plug out on the engine and crank it over, you should see it spark. if not, have a real good look at the wiring, use a multimeter and test continuity between the coil plug and the ecu pinout for any breakdown of the cable. if it does fire, check that the fuel injector for that cylinder is firing, no fuel could also cause this.

if the coil isn't firing and all the cabling check out it might work out cheaper to send the unit to microtech and get it repaired.

[blind_elk]

Is your ECU still under some sort of warranty? Have you spoken to Microtech about it?

[Godzilla32]

If it was fine before, whats the chances the wiring to number 4 has become damaged. If it was heat affected and on its last legs fiddling with it may have finished it off. Good check list there to find out the problem though, text book style