I've checked all of the wires with engine off and can't find anything wrong. I only have the miss when it's really cold (after sitting for a full 24 hrs or more) for about 30 seconds and then it smooths out. This may be contributing to the surge I have at low loads of which I've been assuming was cam surge all along ....hmmm.

Anyway, I don't know how to do tests with engine running ....anyone care to walk me through it. All I know how to do is check for arcing in the dark.

 

How's the coolant level?

 

lol, what does that have to do with it? Actually I do have a low coolant light but the level is fine, the sensor is bad. I've checked the connections of the wires to the opti and the plugs and everything's tight. I just don't know how to diagnose properly with engine running with ohm meter or by visual check at electrode or ....whatever you do.

 

What does that have to do with it you ask? Well I just got done doing the intake gaskets on my lousy Vortec motor in my truck. It developed a problem of sounding like a diesel engine for the first minute or so after start up when it's completely cold. Then the sound went away. Everything is ok after that until the next morning.

The cause I summized was water leaking into the cylinder while it's cold. Then expansion sealed er up. I checked the over flow bottle, dry. Radiator was down about an inch or so. Intake gaskets were wrecked. Replaced them and problem gone.

So LOL all you want. You tell me how many things cause it to run crappy at first while it's cold then clear up.

If your interested, the GM motec engines have a problem with injectors sticking shut until they heat up and cause the problem you are speaking of. But Bosch style injectors don't have that problem.

Doubt the problem you have is ignition related. Fuel related should only get worse with load and going into closed loop.

Oh yeah, one last thing. Where did you check the coolant level? Just at the radiator or at the over flow tank also?

First the overflow goes dry, then the radiator level goes down.

good luck your going to need it.

 

Do you have a scan tool that you can use? You say it only happens on extremely cold days and for a short time. I'd be currious to know if the coolant temp sensor that the computer uses is reading correctly. This has a direct effect on how much fuel enrichment is required on start-up before it goes into closed loop.

 

gonz, sorry about your problem ....I was only lol'ing because I thought you might be kidding but wasn't sure. I don't think it's an injector firing problem because I see black smoke coming out of the tailpipe while it's missing. I have checked the coolant level a few times in both the radiator and the overflow and it's fine, I have bled the system just to be sure there's no air either. My coolant temp levels are normal, the sensor should not be a problem. The problem clears itself up well before closed loop ever comes into play....we're talking 20 - 40 seconds after cold start up in most cases. I have a Scanmaster permanently mounted and no codes, I have Datamaster too but haven't used it since discovering this problem. Thanks for your input anyway.

The problem just feels too much like an ignition miss to not be, but I could be wrong. So anyway, can someone walk me through troubleshooting wires while it's running? I realize this is common stuff so maybe I should just Google it. Sometimes people in here are just really informative that's all. Man I sure hope it's not a leaky intake gasket, it's been awhile since I checked the coolant level so maybe I better look again. It be white smoke if it was coolant though, I'm pretty sure it was black smoke last time I looked but that can be a gray area.

 

Welp, the coolant level is fine. I pulled the driver's side wires off the plugs and put them back on and it doesn't seem as bad, still there though. I wonder if having a spark plug loose would cause the same thing in a way that Gonz' is talking about. As it heats up expansion fills the gap from the loose plug, that's the next thing I need to check I guess .....

BTW, where in the hell is the coolant level sensor? I see one on the waterpump but that's bound to be the temp sensor, how about the level sensor? (I just want to unplug mine for now 'cause it's throwing a false low coolant light)

 

Not sure which side of the radiator. Passenger I think. But it's mounted right on the plastic end cap of the radiator.

 

old post but how did you fix your cold startup miss??
ive done plugs wires temp censor new opti good coil

 

Haven't fixed it yet, but it's not as bad as it was ...beats me. I don't drive the car much this time of year (or ever, really) as it's not my DD so I'm really slow at resolving things. Someone suggested I try leaning the cold start tables a bit but I haven't tried that yet, it acts like it's getting "too much choke" at start-up so leaning the cold tables may help. I haven't even pulled the plugs ..... .....will get to it when I get around to putting my blower back on.