Cold natured 98 LS1?????

[phastls1]

Hello...
I was wondering if anyone can help me with this...when it is cold out my 98 z28 takes for ever to get running right. The idle fluctuates so viloently that the car will die. After it warms up, it is fine or if the temp. outside is 40 or warmer the car runs great. I have had several lt1 cars and have never experienced anything like this (my 1st ls1 car). Any suggestions on the problem...Thanx, Tom

[Roger in Kensington]

Sorry, but I can't be much help . . .

I have never experienced that problem with my '98 TA. What I do experience in cold weather (along with many others, apparently) is for the trip odometer to reset itself to zero. Irritating, but does not affect performance.

What, if any, modifications have been done to the car?

[phastls1]

What, if any, modifications have been done to the car?

As far as I know, the only mod is a flowmaster muffler...there possibly is some ecm mods, but I'm not sure. I bought it used and have driven it maybe 1000 miles since early Sept.

[blackthunder50]

If there was some PCM/ECM changes, maybe the idle settings were changed around for different temps. Maybe find someone to plug a scanner into it when you start it up.

[thenuge876]

That would be the best place to start, have it scanned. Cuz I was thinking it could be a vaccum leak but with it being fine at warmer temps it doesnt fit. So try getting it scanned, im not real sure what it could be but thatll get you pointed in the right direction.

[phastls1]

Thanx for the suggestion folks...I'll try to do that...I never though of that since I never seen any check engine light....

[94 formula]

phastls1-I'm pretty sure the LS1 uses the coolant temperature sensor to decide the A\F ratio until the car hits closed loop and the oxgyen sensors are used. I'd see if that may be causing your problem.

Roger in Kensington-There is a TSB out for LS1's having the trip reset. My brother had this happen to his 99 Z28 you can fix it by replacing the instrument cluster but that is expensive just to have a working tripometer in the cold.

[Roger in Kensington]

Well, as the car has only 28,000 miles on it and . . .

Roger in Kensington-There is a TSB out for LS1's having the trip reset. My brother had this happen to his 99 Z28 you can fix it by replacing the instrument cluster but that is expensive just to have a working tripometer in the cold.

. . . I don't drive it much in the winter anyway, I think I'll just live with the problem. It's a very minor irritant.

[brynnda]

i had a 90 ws6 formula that started throwing a fit when i started it, horrible idle, shed die, smoke out the rear, just a bit. turned out my thermostat was bad. it was reading 40* below 0.

[phastls1]

I think I'll try the coolant temp sensor...It's only around $20 so that's not too bad. And with the miles on the car, couldn't hurt to replace it anyways...thermostat was replaced shortly before I bought the car so I don't think that's it...I did see a sale ad today for advance autoparts and they have an OBD 2 scanner on sale for $99 (described as extremly user friendly), so if all else fails I'm gonna grab one of those as well

[94 formula]

I think I'll try the coolant temp sensor...It's only around $20 so that's not too bad. And with the miles on the car, couldn't hurt to replace it anyways...thermostat was replaced shortly before I bought the car so I don't think that's it...I did see a sale ad today for advance autoparts and they have an OBD 2 scanner on sale for $99 (described as extremly user friendly), so if all else fails I'm gonna grab one of those as well

I'm not sure if its the same on the LS1's but on LT1's there are two different sensors, one that tells the computer the temperature and one that goes to the guage. Make sure if thats how it is on the LS1 to replace the sensor that tells the computer the temp.

[Injuneer]

i had a 90 ws6 formula that started throwing a fit when i started it, horrible idle, shed die, smoke out the rear, just a bit. turned out my thermostat was bad. it was reading 40* below 0.

A reading of 40degF below 0 is symptomatic of a failed coolant temperature sensor, or an open sensor circuit. A failed t'stat would not cause the coolant temp sensor to read -40degF. The PCM has no way to know the t'stat has failed, at least until the engine operheats.