i have a 1998 sunfire, has 190,000 miles, has been running great until the really cold weather hit, now for some reason it is surging. it runs great when i first start it and the engine is cold, as it warms up to when the temp guage gets to right at the normal starting range it will surge while driving and then after a minute or two as it warms up some more it stops surging and runs smooth. not sure what to check so if anyone has an idea let me know. this is more of an annoying problem then anything else as it stays running and clears up after the engine is warmed up to normal.

How long has it been since the car has had a tune up?. Has the cooling system been serviced? How old is youre battery?. Is youre charging system working properly?.

i was thinking a tune up myself rich.

well i don't know when the last tune-up was, i bought this car a few months ago and all i have done to it was put new plugs, air filter, oil & filter. the charging system is working fine as far as i know, the light on the dash for the battery comes on when i first start it and it goes out and doesn't come on while driving. i don't know when the cooling system was last serviced but it has proper level of coolent and i check it and it's good for around -20 degrees. battery was in car also when i got it and there is no sticker anywhere i can find saying how old it is but it looks maybe 1-2 years? posts are clean & tight. also no check engine light while driving just when i first start it then it goes out.

I would recommend getting a digital meter on the battery to confirm its charging properly, And the battery is read the correct 12.5 volts with the car off, If you only replaced the plugs/ I would replace the wires also, Wouldnt hurt to get the fuel filter replaced as well, I fogot to mention in the last post. Thats all I can think of now, What I have explained is cheap trouble shooting, It will $$$$$$ then the mechanic charging u if you got to take it the shop.


GoodLuck.

Intake air leak,fuel pump,injectors,fuel filter,spark plug wires,Have your battery tested and the alternator.Ask some part stores they well help you.When is the last time you had the transmission serviced?

checked the battery, with car engine & ignition off volts at battery are 12.2 volts, car running at idle & when reved up volts at battery are 14.8. i removed the plastic part (can't think of whats it called right now) that attaches to the TB and has the hose from the filter box on other side, when i removed it there is a lot of liquid stuff which i am sure is from blow by all over the inside and on the TB blade, i cleaned off all that i could and reinstalled it, haven't had a chance to drive it yet to see if there is any change. also when i was doing that i noticed a very faint buzz/hum coming from the alt. i know it is coming from that as i used a piece of heater hose and held it to my ear and moved the other end around and i could hear it louder then. car was off and no key in ignition. i am sure that is not normal so i will have to do some checking to see if i can find out whats causing that.