Runs like crap for 5-10 minutes...

[Vett-Klr]

After sitting overnight when I first start up my car it runs like crap until it gets warmed up. I believe it is firing on 3 or 4 cylinders, even is if give it some throttle it shakes like hell missing badly. Once it's warmed up it's fine and as long as it doesnt sit more than a few hours it will be fine next time I start it up. What might cause this? Also it seems to smoke a whole lot while its missing.

 

[cabech984]

maybe running like crap in open loop only. once warmed up it runs fine?

 

[mikestertwo]

What chip are you running?

 

[hemity]

This sounds like the sensor in front of the throttle body under the intake tube . I think its called a idle sensor. Unscrew it with a pair of channel locks then take a can of carb cleaner and spray all around the tip for like 15 seconds with never touching or wiping it. Give it a minute dry and reinstall. This worked for me with the same exact problem.I hope this is it.
Good luck

 

[novaderrik]

if that doesn't work, unplug the temp sender and see if that changes anything.
if the sender is bad, it might think the motor is warmed up all the time, and thus will run it too lean when it's cold.

 

[Fuelie600]

Sounds like a bad/leaking injector. You might be loading a cylinder with fuel after shut down. Check your FP gauge after shut down to see if FP holds. Also, pull the spark plugs prior to start up and see if any are wet. Brian

 

[Vett-Klr]

Well, I'm not sure the two are related but, I found coolant in my oil. I'm not sure how long I've been driving it like that either. Now chances are that the head gasket is blown, but any chance it's simply the intake leaking? I drained the oil, let the car sit overnight and when I drained it the next morning coolant came out (there was no oil in the car and I had not started it). If it is only the intake, how can I be sure. Or should I just pull the motor, replace the head gasket, check the bearings and be done with it? If I do pull the motor what parts should I replace while I'm in there?

 

[SHADOWII]

how long....

has the motor been doing this? if it has just been idle time and low volume of coolant(ie:couple ounces) I doubt if it would have carried thru the oil pump. however, w/your mod's why take the chance. It may have been going on for a time and it just now became noticeable. If nothing else, it will give you peace of mind.

 

[SGRIM]

This sounds like the sensor in front of the throttle body under the intake tube . I think its called a idle sensor. Unscrew it with a pair of channel locks then take a can of carb cleaner and spray all around the tip for like 15 seconds with never touching or wiping it. Give it a minute dry and reinstall. This worked for me with the same exact problem.I hope this is it.
Good luck

You spray it you kill it!