Red92Bird

Well, when you crank the car over cold and it fires up, she seems to run oddly for about the first minute. from the exhaust it sounds kind of like a miss although im not entirely sure that is whats happening. after that the car runs real smooth during the rest of the warmup. seems to be more noticable if the car has sat for a few days. 92 firebird lo3 completely bone stock besides exhaust.

any thoughts??

Jtufts

well its just that cold , i need to give my car gas after she turns on just so she dont idle stall her self

ChillPhatCat

Just a quick guess I'd say you're running a little rich and this is fouling the plugs. It might just be because the temperature outside is causing the computer to richen up the mixture... or it might be a sensor going out. Another idea would be that if you're constantly driving it without letting it fully warm up, this might be a consequence you'll have to live with.

Red92Bird

Well i always let the car warm up so i dont think thats the problem. any ideas on what sensor could cause this? could a bad oxygen sensor be the culprit? i know its been a while since the cars had one.

dimented24x7

iTrader: (2)

If its very cold out, it could be due to the fuel not really having enough heat to vaporize. If it runs fine otherwise, but the idle is off a little for the first minute, then it may not be an issue. Do you still have the stock air cleaner with the thermac? Having that hooked up will help.

ChillPhatCat

Well running rough is either a misfire or engine damage, it's unlikely to be damaged because it sounds like it runs fine once it's warmed up. So I would start checking everything that has to do with ignition and fuel delivery. The easiest thing you can do is throw some dry gas into the gas tank to see if you're having a moisture buildup problem in the fuel tank. Then I always check the oil, check the coolant, smell the exhaust and check the plugs to see if they look like they've been running rich or lean. If the plugs look rich, either clean them up or replace them and see if it makes a difference.

It's really hard to plot a course of action if you haven't checked the basics.

Oxegen sensor is probably not the cause unless you're also getting bad mileage or throwing a code.

dimented24x7

iTrader: (2)

IMHO, if its a little off kilter at idle but runs fine under load when first started at very cold temps and it doesnt have any vac leaks, then its probably ok so long as it clears up after a short time. Might just be a too rich while cranking . Sometimes that will foul the plugs and cause a slight miss. Too rich while cranking is a common problem with the stock calibrations because the computer cant properly meter the crank fueling. Maybe give it a tune-up and see if it improves. Try hooking a vacuum gauge up as well and see what it shows. If the vacuum is below 17 inHg and/or the needle fluctuates alot or has a periodic downtick, then theres issues.

bilms01

I had a similar problem, even though it was a MPFI 3.4 in a Monte Carlo, it might be food for thought. It would run rough when I first started it but cleared after a minute ot two of playing with the throttle, and it was worse after sitting a few days also. After the a few hundred bux worth of ignition parts thrown at it, I found a sticky injector, new injectors no more problem. I haven't seen it on a TBI but I suppose it could be possible.