91 Z28 350 TPI. When cold the car runs and idles rough till it warms up then runs great. Try and give a little help. I'm thinking it may be the cold start valve but not sure. TIA

Scott

 

its not cold start valve. i believe the cold start valve will only be open for a Max of 8 seconds. i may be wrong. but either way it wont effect your idle once u car gets started.. my car does the same thing, and im pretty sure my cause is im running lean at idle. and the ECM locks the BLM's at 128, well acordign to my scan tool anyways.. but im not certain if thats the cause of mine or not..

 

how rough, i mean i start my car up in the morning and it idles at 1k rpm and feels abit rough, but no where near like going to stall or anything like that... i dont drive the car hard at all untill fully warmed up.. like i stay under 2,500 rpm untill i get to 220 engine temp..

 

souds like its running on 6 cyl. Sometimes it will die

 

mine wil stumble when accelerating. like u push the gas and the engine will kinda stumble and the RPMS will go down a little. and then it jumps up. it even does this when in neutral

 

same problem here. with TBI LO3. When it gets below freezing it takes a very long time to fire and then runs like it's got a funnycar cam in it for a few minutes till the idle slows down. Sometimes it will take a shot of starting fluid to even get it running, but sometimes it dies after it runs out or ether. You're probably thinking the fuel lines are freezing, but I hit the dry gas hard in the winter for this reason, even use it in the fall in anticipation of the winter.