stuttering at high rpm

**DOUGLASMELTER** · 05-15-2009

got a 200 gtp with the zzp 1.0 pcm. at *** my car stutters and i can hear a very faint backfire in the exhaust like the spark shuts down for split sexonds at a time. ignition module is ok and cps is new. is this a bad pcm?

**DOUGLASMELTER** · 05-15-2009

ps all of a sudden when this started happening my gas mileage went from 13mpg to 18mgp. love the mileage but would trade it for my old power back anyday

**blueguy** · 05-15-2009

ZZP PCM is why. They are horrible and lost their ability to tune well over a couple years ago. Now everything coming from them is junk. Can we have a ZZP PCM sticky on here so no one buys one? I went through FOUR and they were still wrong...lost my motor about a month after the last one came in. And I was only running a 3.5" pulley with A LOT of mods...

Did you throw any codes? Sounds like a misfire. Maybe new plugs and wires and a new o2 sensor to help with the mpg's...you should start there.

**DOUGLASMELTER** · 05-15-2009

u dont understand the mg went way UP! thats what confused me. one last thing i forgot to say was this happened as the transmission was being rebuilt. could this be it and not the pcm. im no expert but it doesnt feel like the tranny though. is there anything else that could cause this other than the pcm? regardless im buying a hptuner from intense next week anyways. oh and the check engine light never came on but weird thing is i can disconnect the map sensor and maf sensors and the light still doesnt come on and no the bulb isnt broken

**blueguy** · 05-16-2009

1) Keep **** plugged in...unplugging stuff is just meant to diagnose things
2) MPG going up means less fuel = leaner. Probably not good.
3) Change your plugs and wires like I said

**DOUGLASMELTER** · 05-16-2009

okay, plugs and wires are new now and still the same. anything else you suggest

**blueguy** · 05-16-2009

Does the motor make any noises like a rattle or knocking sound? Doesn't sound too good. What are your mods...jw.

**DOUGLASMELTER** · 05-16-2009

she sounds great all the time just a slightly ruff idle and his crap cutting out for very tiny bursts. its killing the power but increasing fuel econ. mods r 1.0 pcm from zzp, msd ignition, k&n cold air kit, off road cat delete, 3.4 pulley

**blueguy** · 05-16-2009

Originally Posted by DOUGLASMELTER

she sounds great all the time just a slightly ruff idle and his crap cutting out for very tiny bursts. its killing the power but increasing fuel econ. mods r 1.0 pcm from zzp, msd ignition, k&n cold air kit, off road cat delete, 3.4 pulley

3.4" is way too small. You might have the first stages of boom coming on.

**DOUGLASMELTER** · 05-16-2009

do you mean detonation? also, why now? the pulley has been on the car for over 4 months and this just started.

**Scimmia** · 05-16-2009

Well, what have you done recently? I'd be taking a look at the plugs and wires from what you're describing.

**Sabrewings** · 05-16-2009

Originally Posted by Scimmia

Well, what have you done recently? I'd be taking a look at the plugs and wires from what you're describing.

Or coil packs.

**DOUGLASMELTER** · 05-16-2009

checked plugs and they r good. wires too. msd ignition coils good too as they were my first thought i tested them twice to be sure. did you know it huts to remove the plug wires while the vehicle is running lol. the only recent repair is the tranny was totally rebuilt but thats not it as it actually happened for the first time as i took it to the shop. nothing new in 3 months.

**DOUGLASMELTER** · 05-16-2009

trust me im quite confused.

**Scimmia** · 05-16-2009

Do you still have the stock coils around? MSD coils and supposed to be a downgrade for the GTP, and MSD wires are very hit or miss, and are known to cause misfires in some cases.

**DOUGLASMELTER** · 05-16-2009

two coils failed so they r gone and i through the other out when i bought the entire set. you think its the coils too? like i said i really thought that was it myself but they read perfect on my ohm meter and they arc like crazy with no wire

**DOUGLASMELTER** · 05-16-2009

just pulled them all and tested again and they r all perfect

**Sabrewings** · 05-16-2009

I've seen coils pass the resistance checks but still be bad. Stuttering is an ignition issue. You've replaced the plugs and wires. Coils would be next. Then the ICM (which is rare to be bad).