KLZE performing bad at high RPMs

[unclegreg]

Have som problems with my MX3 -92, KLZE.

Have bad MPG, when I changed plugs last time they were really black, so im assuming it's running rich. Also have problems at high RPMs, loses power and it always struggles above 6k (sometimes it dont get past 6.5RPM). Also think it's kind of slow in general.

Currently running KL36/JE50.
I've tried K8/JE50 = bouncing idle, bad low end power, jerking (runs fine only when accelerating), still bad above 6k
Probinator chipped K8/JE50/KL02 - strangely it runs crap with this ECU, bouncing idle and black smoke from exhaust
Kind of funny that i've got a steady idle with KL36 but not with the other two..?

I've changed:
Plugs, wires, fuel pump, fuel filter, new CAI, ECTS sensor, distributor with HEI, changed and adjusted TPS, timing is spot on, no cat.

So the main problem is around 5,5 to 7K RPM, where its performing really bad, i assume because of it running really rich.
Need some input of you guys since im beginning to loose faith.

[wytbishop]

well your description of running badly at higher rpm leads me to think it's an ignition issue. Good spark at low rpm but not at higher rpm. Either that or the timing is not advancing. That could also account for some of the poor fuel economy.

Have you checked codes?

[unclegreg]

Yes, I forgot to mention that. No codes, except for 3 EGR related (when reading with K8). Since it's a ZE it has no EGR though.

[Rick Johnson]

Are your VRIS working properly?

[Gro Harlem]

VRIS valves opening? you can check this while its parked. Just rev it and watch the two valves on the back of the intake manifold to see if they open the butterfly valves. one should open then both should open at the same time depending on RPM. You shouldn't have to rev it past 4k though to have both open.

[PATDIESEL]

How are you running the vacuum to your fuel pressure regulator and which intake manifold are you using?

[Daninski]

Did you diconnect the negative from the battery and depress the brake pedal for 15 secs to clear the ECU memory in between trying different ECU VAF combinations?

[unclegreg]

VRIS is working fine. I have tested different ECUs and reset each one of them. Intake manifold is Curved Neck from Eunos 800. Vacuum goes from intake to FPR.

When i got time i will check cam timing to confirm that its not 1 tooth off. Does anyone know if you could destroy a FPR with the higher flowing Walbro 255 HP? I had that installed for two months, but now using stock ebay pump.

[wytbishop]

My money's still on the ignition system.

[unclegreg]

Good news!
It seems to be working fine now! I changed the HEI-module and redid all the wiring. It performs well all the way to the redline now. At least it did on my quickdrive. Snow and summer tires isnt such a great combo.

[RX8SE3P]

wytbishop wins

[wytbishop]

I'm not sayin'. I'm just sayin'.