06MS6

Hey all,

I have a 1990 Miata with a turbo and COP setup. When I purchased the car, everything was fine but randomly started acting up.

Exactly at 3k RPM, the injectors lose pulse (I verified this by hooking up an oscilloscope to the PCM). I checked every single input related to the fuel injectors and none of them seemed to lose signal when the injectors did. I also wired a separate ground from the battery to the ground bus, and the injectors still went flat. I purchased a used PCM off of ebay and it had the same problem. The resistance of the injectors is also within spec.

I'm at a loss here and would really appreciate some input.

Braineack

iTrader: (62)

Id be more inclined to think it was your CAS. Especially considering it's like the only thing your ODB-I reports back AND you're throwing a CEL.

06MS6

I thought the same thing, but the CAS does not lose pulse when hooked up to the oscilloscope. The spark plugs are also firing when they need to...

Braineack

iTrader: (62)

make sense since the tach isn't going crazy either. but i can hear/see that your fueling goes to complete ****.

is it all injectors or just one pairing?

06MS6

All the injectors are causing the problem. I unplugged each one to verify as well and it does the same thing.

therieldeal

iTrader: (2)

Are they hi-z or lo-z injectors?

Many years ago i had issues with flyback voltage spikes from lo-z injectors causing issues with my megasquirt. Swapped in hi-z injectors and never had a problem again.

06MS6

I am not exactly sure, but I believe the injectors are stock.