ignition break up, high RPM

[93supercoupe]

Hey guys, quick question

My car breaks up at 6000rpm (7200 rev limit) at around 11psi of boost. Ive tried the conventional plug gap, new coil boots ect.,, but i have a simple question

If my trigger log doesnt log any errors, can i assume that its not my crank sensor/noise/interference in that circuit?

Ive got a new set of coils coming on monday, but i just wanna check my basis first.

Thanks again

[grom_e30]

if there is no reported sync loss you should be good, what about dwell time

[93supercoupe]

Mines set to 2.7ms at 14v which seems right from what ive read.

In the stock harness, theres a ground for the coils (pin 15). This ground goes from the the ECU, to each coil, then to an inline resistor, then grounds to the head. I measure 230ohms between the ECU pin and the point at which it grounds to the head. Tested 2 harnesses, both got 230.

Pin 45 is shown to be a shielding wire for the ground wire?

What should i do with these 2 pins? go right to a mainboard ground with each? tie them together and bring them to a single mainboard ground? or something else?

And 1 other ground question. The raw wire strand wrapped in the crank sensor wiring, where should this end up on the engine harness side?



Thank you all, just trying to have my ducks in a row for the dyno!!

[grom_e30]

have you still get the resistors in there?

[93supercoupe]

have you still get the resistors in there?

yea, i left it all stock

[grom_e30]

wondering if thats causing spark loss energy, i take it there a 3 wire coil? so power ground, and signal ground from ecu via quad spark boxes?? is it?

[93supercoupe]

Thats plausible for sure. Im not even clear on the operation of the ground wire. It has a key switched 12v, then a ground going to the ECU (high current driver) and then this ground. So each coil has this ground lead and the all splice right at the injector rail and goto head ground. The only time that it connects to the ecu pin 15 is threw a tiny tiny shielded wire that meets up in the splice at the injector rail.

So im not even sure what it does.

[grom_e30]

cant comment on that running back to the ecu with the shield wire id leave that well away from the ms3 though, and possibly try wiping the resistor out see if it helps.

[93supercoupe]

So i brought the shielding wires 15 and 45 to a mainboard ground, and also grounded the shielding strans of the crank sensor, along with brand new OEM coils and boots, and its still breaking up above 6k.

2nd gear i can make it to limiter with only a small amount of popping, but higher gears break up 6-6500.

I did notice that the tach drops out when it breaks up. I havent taken a trigger log in a while, maybe i should. The last time i did, it had no errors.

[grom_e30]

if the tach is dropping i think it may be losing sync, pretty sure when i was getting a ignition misfire on my bike at 11,500rpm the tack stayed fine. time to log it.

[93supercoupe]

I had an ignition setting flipped around. The one that suggests the wrong setting could cause the timing to walk. After I flipped it around, it now runs amazing. 15psi and 11degrees of timing and she's still a rocket. It's gotta be close to 400hp/400tq

Dyno time Saturday with 93 pump and meth. I'm excited!!!

[93supercoupe]

Thank you grom!!!

[grom_e30]

GOOD STUFF

[rdclark123]

93supercoupe....What setting did you change around to fix the problem? I have the same problem.