1JZ-GTE Missing

[Cressida25T]

Hey guys, I have a 1JZ-GTE (JZX81) running Microtech LT12S with X6 Igniters. It was missing in one or two cylinders. So far I've pulled all the coils and repaired any hairline cracks, and cleaned the spark plugs - weren't too badly carbon'd up. Reinstalled, same problems.

The car hasnt been run for very long in the past few months so is it wise/safe to give it a light run up to operating temperature?

What should be my next move to diagnose the problem before I have to get an auto electrician out?

Any replies appreciated

[TRD-12A]

Compression test straight up make sure its within specs. How many hairline cracks were there? you have to look for white track marks which indicates spark isnt getting to plug. What did you use to repair the cracks. Use electrical tape to see if it works the best thing to do is replace that coil.

[Cressida25T]

There were a few hairline cracks on each coil - seems to be a common problem in 1j's. I repaired them using liquid electrical tape and then heatshrink over the top (as per a quick-fix thread poster here).

Weren't any white track marks, spark plugs cleaned up nicely with some brake cleaner and wire brush.

The car isn't registered so I can't take it to a workshop for a comp test, perhaps someone knows a mobile mechanic (North Bris) who does them?

Do you think it's wise to run the car up and back in my street to see if some heat will clean out the cobwebs (haha seems to work for my 7mge )?

[TRD-12A]

Give it a go man and see if it still misses after its warmed up properly.

Are the plugs platinum tipped or just standard 1J are normally platinum if they are by cleaning them you may have damaged them so they may need replacing.

[TasCressida]

just a quick note.
my 1jz fouled the plugs the other day. Cleaned them up with wire brush and a can of brake cleaner thinking it would be sweet cause they were really clean. The missing got slightly worse.
went to parts supplier and was informed that brake cleaner will kill plugs if u clean them with it.
Brought new plugs and hey presto all was fine.
so id replace them. just to be sure.

Also if your running stock coils check the 2 pin plug on each coil. the have a tendacy to de pin them selves. check the pin in the plug is actually making a full connection on each coil.
This problem caused a miss when i was running factory coils.

all else failing that ..... do the LS Chev V8 coil conversion. Ive never looked since doing that.

[TIMTAMS]

everytime i put plugs in my cressy i had to gap them right down to .7 or .6 otherwise it would miss under load.

What gaps are u running?

[TasCressida]

oh and if u replace the plugs just use base series NGK items. Ive had nothing but dramas with Platinums and iridiums.
Just my personal experience there though.

[TasCressida]

i run mine at .7 1 other wise it misses on boost.
i used a NGK at 1.1 and it was fine on low boost but would miss and foul them on 16psi plus. And would wet the plug badly on cold start.
Same plug with a .7 gap is perfect though. even on 20 psi.

[Cressida25T]

I'm using standard NGK's at the moment, will get new ones and gap accordingly.

How do I go about isolating the missing cylinder/s?

[lexsmaz]

It sounds like it is missing all the time even at idle ? if it is still missing at idle just pull off an injector lead at a time & refit & then pull off another one until you find the offending cylinder .. And as the others have mentioned put in new plugs dont waste your time cleaning them it often wont work & once you have tracked down the cylinder & tried a new plug to no avail ? you will need to do a compression test & go from there ..

[TasCressida]

what part number NGK's are u using?
i reccommend NGK- BKR-5E 's.
Dont let them palm BKR-5E-11 to you though.
thats a 1.1 gap.
Just normal 5E's .
Try them.

cheers

[chris davey]

he is using bkr7e's gapped to .7mm. It is possible that the plugs are fouled as the cold start was still pretty rich.


I would change the plugs first and I think it will probably be it. It did that in the past but I did lean the cold start a bit but maybe not enough.

[Draven]

hairline cracks in the coil packs is not necessarily a problem - it's only if it's causing the col to not spark correctly that it becomes a problem.

If it's a constant miss, you can check which cylinder it is by pulling the power from one coil pack at a time and see which one makes no difference.

I've always used BKR6E on standard engines, have gone up to BKR7E for my modded 2j

[Cressida25T]

Thanks for the replies. 6 fresh BKR-5E's did the trick, purring like a kitten now.

The plugs I pulled out and cleaned 3 days ago were caked in carbon, so I fear these plugs will be eaten in no time without a tune :S.