Hot start issue

**98GPGT2D** · 04-10-2011

Hey guys, got a hot start problem here. Well, not so much of a problem, more of an annoyance.

Anywho, cold start, starts fine, no issues.

Warm start, it fires right away without any issues, but runs like a small block with one hell of a lump stick in it. Give it about 4 or 5 seconds and it clears up and runs fine. I replaced the plugs and wires about 10,000Kms ago. Just removed and cleaned the MAF and IAT sensors with the Gunk brand sensor cleaner.

Car is a 98 GrandPrix GT with a 3.8L, 257,000Kms.

Jay

**Jaybird** · 04-11-2011

Coil pack. hard to catch which one since it's intermittant. Timing light might work...

**98GPGT2D** · 04-11-2011

Originally Posted by Jaybird

Coil pack. hard to catch which one since it's intermittant. Timing light might work...

Think so? Even though it clears up and runs perfectly after a couple seconds? Once its running good it never bobbles or hesitates or misses.

From my experiances, usually when a coil pack takes a dump, it works fine when cold, but as it warms it breaks down internally and just quits. Let it cool to ambient temperature and re-start and its fine till it warms up again.. Thats how small engine coils go anyways...

Any way to ohm out the coil when its hot and cold? Anyone have any specs on it?

Jay

**Jaybird** · 04-12-2011

Try pulling the coils and cleaning the base and mounting plate as these are contact areas.

**KZOO3800** · 04-12-2011

I've posted rather over-extensively on this exact issue. My car: '97 Grand Prix SE with 3.8 NA. 164K miles. Cold starts = beautiful. Warm starts = 5-10 seconds of chug. I also cleaned MAF and put in new air filter. Didn't think to clean IAT but I doubt that would help. I'll try it anyways and let you know. My plugs and wires were also replaced about 3K miles ago by me, and on my second oil filter since I just did second oil change in 4K miles. Lucas Oil Stabilizer used for 20% capacity, new plugs and wires when I bought it.

I know next to nothing about the coil packs, all my other cars had cap and rotor. Have you changed your fuel filter? Mine is old as fu**, and my fuel line has to be replaced with the fuel filter because its so rusted that it would break it to take the filter off. Are you getting an abrubt "snap" to idle speed with your warm starts? My guess is as good as yours, but I also suspect EGR, LIM gasket, small exhaust leaks, and possibly the MAP sensor. Of course, my fuel filter being ancient means my fuel injectors are probably screwed too.

Check your engine bay fuse box, my micro-relay #15 is missing, discovered that yesterday and it controls fuel pump and speed sensor or something like that.

**98GPGT2D** · 04-12-2011

Well, I was poking around under the hood tonight after work..brought my stethoscope home, found a vacuum leak. Check out where the TB meets the plenum. I dont know if the previous owner had the TB off for some reason and didnt get it seated correctly, or if the Plenum is warped.. What are your thoughts?
I can deff hear a vacuum leak here without a doubt.

FRONT SIDE

BACK SIDE

Jay