ishootstuf

iTrader: (1)

I tried searching, but I either suck or the answer is not out there. I'm good either way.

I replaced the head gasket on my NA-T 95 SC300. The car idles and runs beautiful as long as I don't try to make any power. The car is actually faster if I keep it under 25% throttle compared to WOT. I know it must be related to the head job because other than leaking oil and running a bit rough, the car was still pretty powerful with the blown head gasket.

It's worse when warm
It's worse when timing is retarded to stock - I'm running 15 degrees BTDC
I was able to "see" the misfire using a timing light while power braking
AFR goes rich when I floor it then slowly goes lean

Spark plugs gapped to .035" - same plugs that worked great before
EDIT: New plugs installed
New cap and rotor
Wires are less than 2 years old.
Problem MAY have improved slightly when I added an extra ground to the head, but it's hard to tell.

I can actually feel something change as I increase throttle. It will be breaking up, then I slowly reduce throttle and boom it takes off. I made no changes to the TPS during the head job.

What did I not plug in or hook up wrong?

craaaazzy

iTrader: (4)

how much boost u running?

u definitely need to gap those plugs down, i say at least .028. i'm at .026 myself. was still breaking up every so often. now i have an ignition amplifier and haven't seen it happen yet but only drove it once for a short time since installing it.

ishootstuf

iTrader: (1)

Boost is not the problem. This issue still happens when I disconnect the intercooler piping basically turning the car back into a NA. But, to answer your question, I'm currently only running 8 PSI until I get this resolved. I was running 11 with my plugs gapped at .035" and never had issues - with spark anyway.

rykwebb

coil packs? not running strong enough spark plugs (BKR7s or BKR8s)? ummm...air/fuel ratio through your electronics? running too rich? Dunno...

Biggu

iTrader: (12)

sounds to me like spark blowout.

what plugs are your running?

get some NGK BKR7E's and gap them to .027

either that or you need a better tune.

ishootstuf

iTrader: (1)

I just installed NGK V-Power BKR5EYA-11 this morning. I was running BKR6ES-11. No change.

It's not spark blowout. It happens when I cap the intercooler pipes and run NA. I started off gapped at .028" and it still had the issue. It's not tuning either. Mad rich, mad lean, no matter what - it breaks up.

ishootstuf

iTrader: (1)

I don't have coil packs. I have tried all different AFR's. I'm convinced it's ignition, not air or fuel - but I could be wrong... I'd think if it were fuel, I wouldn't be able to make it rich, and it would only break up when it went lean.

v8soarer91

check the spark gap and heat range
coil packs for cracks
sensors
remove the afc neo (use the std ecu)
then ecu

im guessing that when the timing belt was installed the motor was not at top dead center on the 1st piston or the timing marks on the cam gears are out.

Biggu

iTrader: (12)

both those plugs are not the correct plug for your application a BKR5EYA-11 should be used with a N/A car.

ishootstuf

iTrader: (1)

It doesn't matter. The car was running good prior to replacing the head gasket. It's not the plugs. It's got to be related to the work done. I just don't know where to start.

ishootstuf

iTrader: (1)

No coil packs
What sensors could be causing me to lose spark under load?
Tried different ECU already, and the Neo can't cut spark - can only affect fuel.
Valve timing is good - and can't affect losing spark, only timing it.

2jzlex

iTrader: (3)

Did all of this happen after the headgasket job? Or did it happen before? If it happened before, how/when did it happen? Such as; boosting and it just starting running like crap? You fired it up and it was having problems? Kind of asking what circumstances did it happen under if you get what I mean. That's the first thing we need to know.

*Edit. Nevermind. I missed it. Start with the basics. If you're positive it's ignition related, make sure you're gettin fire to all cylinders first. If this is good, check everything thoroughly for cracks. If a boot is cracked, plug wire is split, and that arc jumps to the head, it can cause problems that you're describing. Dbl check your reinstall and make sure that all your timing marks are lining up on the belt, damper, and timing cover.

ishootstuf

iTrader: (1)

Yes, all happened after. The car ran fine before. It's related to the job, but every connector, vacuum line, and setting I check seems correct. I don't know where to start.

2jzlex

iTrader: (3)

Start with spark to each cylinder and the cracks, then let us know.

craaaazzy

iTrader: (4)

^^^any of those could have happened to the wires when u were removing/installing parts to get to the headgasket so double check them.