gtp bad miss

**Rico** · 04-10-2012

P0135, aye? Could it be injector related or O2 sensor? A good scan couldn't hurt.
Do you have an Aeroforce or anything else?

EDITED: Sorry, I just noticed that you do have a scanner.

**Rico** · 04-10-2012

Have you tried removing the supercharger belt and run it? Is it missing only under boost?

**jrock** · 04-10-2012

wellhow do i check the injectors

**Rico** · 04-10-2012

You can check the signal going to them with a DVM set on duty cycle but this will only tell you if the PCM is commanding them correctly at idle.
I remove them and wire them up to 12 Volt (with switch) and a can of carb cleaner attached to the inlet and go to town. A 1000mL graduated cylinder works great for time vs volume checks. Only problem is you'll go through a lot of carb cleaner.

Have you checked fuel pressure? I guess you would see a lean condition on the Aeroforce though.

**Rico** · 04-10-2012

Some other things to check:

TPS - Idle about 1V and WOT about 5V (someone correct me if I'm wrong)
MAF - These can get real flakey but you'll see crazy things on the Aeroforce like AFR and timing all over the place.
MAP - I have never personally seen one of these go bad.
Knock Sensors - You said that header install dropped retard from 4 to 7 down to 2.9, but who knows?
I can see KR causing a loss of power but not a bad miss. I could be wrong.
Injector wiring or any other wires - Did you compromise any wires during the header install?

I think that a bad O2 sensor or a wiring issue would set a code since the output fingerprint of the sensor is closely scrutinised by the PCM. And you do have a P0135. So I would start there.

**jrock** · 04-10-2012

just noticed about the maf. my ignition advance is everywhere reading 15.0 to 46

**Rico** · 04-11-2012

Originally Posted by jrock

just noticed about the maf. my ignition advance is everywhere reading 15.0 to 46

We're kinda out of my realm of expertise but I think on heavy acceleration the timing and fueling are being controlled in speed density mode. The PCM is commanding these right from tables and some input signals are disregarded. I don't know if what you're seeing is normal.

Any tuners out there want to chime in?

**Fivefingerdeathpunch** · 04-11-2012

timing is always going to be all over the charts, its adjusting for his foot, on and off the gas.

timing adv should lock in around a givin number at WOT.

Seeing how its been a few days here.

What exactly is going on now?

Which cylinder is giving the misfire?

**Rico** · 04-11-2012

Originally Posted by Fivefingerdeathpunch

timing is always going to be all over the charts, its adjusting for his foot, on and off the gas.

timing adv should lock in around a givin number at WOT.

Seeing how its been a few days here.

What exactly is going on now?

Which cylinder is giving the misfire?

Thanks man, we need some help.