Thread: Gtp issues

I have 98 Gtp having misfire in cylinder 3 and 4 only at idle . On the highway I could be doing 75 and try and give it gas slowly and it sounds like it's bogging down till supercharger makes boost . My abs light and tsc off light stays on and recent had swap back to stock pcm after a ecu malfunction code which made my car shift really hard and delayed . Changed plugs and coil paks wires check injectors . And tryed to swap things around to chase the misfire but no movement. My interceptor gauge reads 14 misses in 4 in the cycle scan and 2 in cylinder 3 . I checked plugs the had orange tips normalburn idk . I know I need new pcm but unsure of my setup . 3.5 pulley cold air intake stock injectors and slp exhaust . Any tips ?

Originally Posted by Fivefingerdeathpunch

He didn't say thing about octane though, so you don't have proof of that.

More so would the pulley drop without enough exhaust mods could chip a piston.

What kind of plugs are you running and what gap?

Stock acdelco uraduim100 thousand mile ones and I use 92-93 gas everytime stock header down to the u bend then it's slp out tryed changing coils with used working ones and moving them around even wires And third gear Boggs like hell got to push pedal to get it outta the bogging .

Plugs came pre gapped on count of the tiny electrode.

Originally Posted by BillBoost37

So .060" on iridium plugs with a 3.5 and no other real flow mods.



Which plug fouling would you say it looks like?

All the plugs looked fine but he was running autolites cylinder 4 is the worst and cylinder 2 and 3 sometimes when cruising but at idle it number four and three will pop up once in while.

Prong was orange with clean burn rest was black chard I was told it was a normal looking plug wasn't shinny or burnt or wet

The second one by the tiny image