Thread: 98 GTP starts and dies intermittently on cold starts

Hey everyone, I have a 98 GTP with 255k miles on it. Once in a while, typically after 15-20 cold starts, the car will start, and die almost instantly. Today, for instance, the car started and died 5 times in a row before it would stay running. When it does finally run, it will idle very rough for about 3-5 seconds and smooth out. The car runs fine any other time, and most starts it has no problem. I had an issue in February where the car idled rough when warm and set a code. This ended up being a cracked EGR tube which I replaced with a new tube from the dealer. I also took the time to clean all the carbon from the throttle body when I did this.

I have a scanner and can check the fuel trim when running, and it doesn't seem to have a vacuum leak when warmed up. I have checked the fuel pressure. The car has about 55 psi when you turn the key, then drops to 50 after the pump stops running. I have seen it as low as 44 psi while idling. The car does have the new fuel pump resistor installed. I also checked the fuel pressure once when the car started and died, but it was right at 50 psi and the car started fine on the second try. Fuel filter was changed back in February when I was diagnosing the rough idle. I am unsure if the pump is original (I hope not) or if it has been replaced, as I've only put about 20k on the car myself.

Last summer I replaced the intake manifolds, injector o-rings, and some other top end items when I had the front cradle out of the car for a transmission swap. I have also replaced the plastic vacuum lines around the supercharger with rubber hose, as the plastic was brittle and cracking.

One issue I do know of, is that the rear manifold has an exhaust leak when cold, but goes away after it warms up. It hasn't been bad enough for me to repair yet, considering what a pain it is to get back there.

I've done my research, and haven't found many people with the same issue. I have seen someone recommend that the crank position sensor could be bad. Is there any way to test this?

Thanks for any input!

I've always wondered about the IAC valve. I guess I could unplug it and see how it starts, but that may not tell me anything. I actually had the car start, idle rough at about 300-400 rpms for about a second, then die after it was warmed up today. Still not sure what to think, but will continue to do some research.

A lot of times being cold and dieing could be weak ignition. Have u ever changed ur plugs? Could be maf also check it to see if its dirty

I installed some Autolite 606 copper plugs a while back. Just looked at my maintenance records and they have 20k on them.... probably about due for some new ones. I pulled a couple out about 5k miles ago and they looked like they had worn some, but were still usable. Hard to believe its been 5k miles since then, but I will be ordering some new plugs to put in there regardless!

Installed AC Delco 41-101 iridium plugs today. Didn't want to start on the first crank afterwards, so the plugs weren't at fault. I replaced the IAC with another used unit, so we will see how that works out. The no start issuing has been more frequent lately. I cant get the car to even start when it acts up without giving it some throttle.

That sounds like a maf problem. With it running tap on it lightly with ur hand shouldn't stumble or attempt to die if so I'd replace it! Did u check to see if the element was clean on ur maf?

I've replaced the IAC with positive results. I haven't had the car start and die on me for a week and a half. I'm hoping that was the fix! Thanks for all the suggestions.