2001 3100 misses when cold

[tractorman]

The wife's lumina has developed a problem. Lately when I start it up cold, it misses and the idle surges. It doesn't do it every time. Sometimes I can rev it up once, and then it runs fine... but sometimes I pull out of the driveway with it missing, and it keeps missing for about half a mile then clears up. Today it missed for about 1/2 mile, and the check engine light flashed a couple times then went out. Would I be able to get any codes now, or will that only work if the engine light is actually staying on?

Once it quits missing, it runs great. The plugs and wires are new- about a month old. The fuel filter is just a few months old. I changed the LIM gaskets maybe a month back, but this has only started recently. Any ideas?

[tractorman]

This morning I noticed that the cheapass Advance Auto Parts PCV valve was rattling. I replaced it with a better brand. The new one doesn't rattle, and the car idles a couple hundred RPM lower than it did before. Don't know if this was THE problem, or just A problem. I guess I'll know after several more cold starts.

I also tried getting codes with a reader. Apparently the check engine light actually has to be on before it'll give me a code.

[tractorman]

The wife has informed me that my latest repair (the pcv valve) did not eliminate the cold miss.

C'mon folks- help a feller out.

[sharkey]

if the cel comes on, it will store a code under history. it would have set a soft code, meaning the CEL will come on, then go out once whatever it set the code for is acting ok, but it will still have a code.

in case you are wondering, a hard code is a code that turned the cel on and keeps it on till its fixed. typicaly this is something major, and the engine is put into a failsafe mode. something like a sensor being bad or unhooked will cause this.

[tractorman]

After the check engine light flashed, I took the car over to Advance Auto Parts and borrowed their code reader. It showed no codes. Maybe it only reads 'hard codes'?

[tractorman]

Well, Sharkey- thanks for the attempt anyway. The rest of ya'll bite me. heh.

The cold start miss problem has been solved. I got tired of the wife bitching about it, so I drove the truck and she drove her old corsica whilst I tinkered with the Lumina. I attacked the problem as if it were a tractor. The sonofabitch would only miss reliably for about 10 seconds every morning, after that it might or might not miss occasionally for up to a minute.... so this process took several days.

First I used the paper clip trick, grounded out cylinders and determined that it was definitely the #3 cylinder that missed. I checked the fuel pressure pressure, and it was ok. Well, it was about 50, and didn't change regardless of whether the engine was missing or not- so that's probably ok. I swapped the positions of two coils and re-checked the miss: the next morning it still missed on #3. Then I replaced the #3 plug wire with one off my old ford truck, and swapped the #1 and #3 plugs. LO AND BEHOLD, the next morning... it missed on #1! Glory to Jebus!

I swapped out the bad plug, put the wires back in place, removed the paper clips and ground wire. Started it this morning, and it ran smooth as can be.

I had always assumed that an ignition problem with one of these engines would neccesarily cause a miss on two cylinders. I was WRONG. That brand new standard A/C Delco plug must've been shorting internally. I couldn't SEE anything wrong with it, but I could turn the glass insulator slightly in the metal. Now it's got 5 a/c's and 1 champion.