First W Body

[02GTP 91WS6]

Hey everyone,

Yesterday I bought my first W body and 4th Pontiac, a 2002 GTP coupe. I recently sold an 85 Fiero GT and still have my 91 TA and a 2006 G6 Coupe. The GTP has 80k miles, very clean, with the following mods:

2.9 Pulley
Polished Gen V Supercharger
N* Throttle Body
ZZP full size intercooler
TOG Ceramic coated headers
Full Custom Exhaust
GXP brakes
Full Dyno tune



I just wanted to introduce myself, as well as present a problem that came with the car:

The idle is somewhat rough. Never enough to stall, but it surges after warmup. I was told it was normal and done after the tune, but I wanted to get your opinions as well. From what I've noticed so far, it's had no impact on drive ability, but it is still a concern I have. Was told there is no vacuum leak.

[Fivefingerdeathpunch]

Without seeing a data log of the vehicle running with the tuner I can't really comment on the surging.

A aftermarket camshaft will lope/surge at idle but you didn't list a cam upgrade. Smoke test to be positive for vaccum leaks, don't just trust what people say.

[blueguy91]

OOOOH, C5!

That's more important.

Welcome to the site!!

[02GTP 91WS6]

Without seeing a data log of the vehicle running with the tuner I can't really comment on the surging.

A aftermarket camshaft will lope/surge at idle but you didn't list a cam upgrade. Smoke test to be positive for vaccum leaks, don't just trust what people say.

Right, I'll double check for a vacuum leak in the coming days. Yeah there's definitely no loping. Thanks for the suggestion

[02GTP 91WS6]

OOOOH, C5!

That's more important.

Welcome to the site!!

He inherited it from his dad so the wife was making him sell one or the other to have garage space so the GTP had to go lol

[buickman104]

Although nowhere near as modded as you mine does the same thing. Do you have poly or solid mounts as well?

[02GTP 91WS6]

Although nowhere near as modded as you mine does the same thing. Do you have poly or solid mounts as well?

Sorry for the late reply, I'm pretty sure they're solid. It also has a weird "moaning" sound that has been present for ~5 years. He had a tuning video on Youtube where the sound was present and nobody could track down the issue. I initially thought a belt or pulley but even after shutoff it fades away after 1-2 seconds. No performance impact or issues, but that coupled with the idle is pointing me to a vacuum leak.

[Slick2500]

Link to the video?

[02GTP 91WS6]

Link to the video?

https://www.youtube.com/watch?v=OJCBfEhdLhE

It's really subtle, but I can take a video in the coming days where it's more audible. Doing a LIM gasket replacement this weekend so it's back at home right now

[fst]

the car and video looks so familiar (not in a bad way mind you) as well as the username bcartman2 .

[02GTP 91WS6]

Yeah I looked him up before buying the car, he was doing this build himself around 2011-2012 and asked some questions on a couple forums. He was an awesome guy and had a folder of paperwork and receipts from the past 6 years