Hi everybody. I'm new here but I've owned my '00 GTP for three and a half years now. It's my first car and overall it has given me a fair amount of issues but I still love it.
Anyways I've modded my car from stock to safely run a 3.5 inch supercharger pulley. My knock retard numbers are under 3 at heavy throttle (usually when shifting so I'm not really worried about KR). I'm happy with the extra power, but lately I've been having a frustrating issue with engine hesitation at highway speeds. Basically when applying light throttle to maintain a speed going up a hill or passing somebody on the highway, the RPM's surge back and forth and it feels like the car is hesitating, until I give it more gas and it downshifts then it runs smooth again.
I'm no stranger to this issue. I had the same problem when the car was stock a couple of years back and new OEM plugs and wires fixed it. Only problem is this time the car is modded and I put in colder spark plugs and a reprogrammed PCM. As recommended personally by Will Overkill, I'm running AC-Delco 41-104 iridium plugs (same plugs used in C6 Corvette, Camaro ZL1, CTS-V, etc.) with a .045 gap. I first noticed this issue when the weather got cold here in Massachusetts. I have no check engine lights and my scan gauge shows no misfires. I've had my fuel filter and lines replaced and my MAF sensor cleaned off and have had no improvements. I'm doubtful that this is a transmission/TCC issue. The car idles, shifts and drives around town perfectly, just on the highway do I have this issue.
So do any of you think that my engine surging/hesitating might be caused by spark plugs that are too cold? Should I try some different plugs? Or could there be something wrong with my tune?
Mods: Wizair Cold Air Intake, ZZP 3 inch downpipe, ZZP PLog, 180* thermostat, Overkill PCM, 3.5 inch press on pulley, AC-Delco 41-104 plugs (with AC-Delco wires)
I run Mobil 1 oil and 93 octane gas. The car has 115k miles.
Please let me know what you all think! Thanks so much!
