80k miles and started stalling when cold at low speed. I am thinking idle air temp sensor. Any Suggestions?

 

You are on the right track with thr IAC. Take it apart and give it a good cleaning and it should be good as new. Let me know.

 

I have same problem with my 99 GM.


It misses for a few minutes,then it runs fine.Only happens on cold mornings and car sits outside.Has to be below 20 degrees.


Replaced IAC,plugs,2 coils,coolant temp sensor and had the injectors flushed out through the fuel rail.


Still does it.Gonna try swapping the air temp sensor with my other GM and see if it helps.


Any suggestions?


Thanks

 

check the battery for weak cells. (take it to the parts house and have them check your battery if you don''t have a battery load tester). if you have a multimeter, you can do this yourself. hook it to the battery. will prolly read around 12.5V. put it where you can see it from the driver seat and not get it tangled in any belts or fans, etc. start the car. if the voltage drops to around 10.x then there''s one weak cell. if you have a big battery, it might still crank it while dropping to 8.x. this would essentially kill the computer each time you crank the car and it will have to re-learn it''s idle again. Takes a few minutes.

other things to check might be the mass air flow sensor and throttle position sensor. but I''m betting a weak battery. need to replace the battery in my wife''s car. it''s got a weak cell.

 

 

Have replaced the battery too.Same condition.


Is there a way to check which cylinder is misfiring while it is running?


Thinking it must be either a weak coil or injector.


I am really getting frustrated with this one.


Have 2 other 97 GM and never a problem with these 2.


Was 7 below this morning and it was having a hard time after cold start until it warmed up.


Any other ideas?


Thanks

 

if any cylinder is misfiring you should get engine codes that tell you that. have you replaced the wires? (I noticed almost everything else was listed but not wires)

if you have a lot of miles on the car (in excess of 150-200K) then that may be it. Also, if the oil is too thick, it will cause this problem. Like using 10W40 in a car that needs 5W30... etc.

my MGM runs a little better with 10W30 than 10W40 (even though the manual says either is good) in the winter (all month of it we have in north Texas). I bet going to a thinner oil in the winter would help in your case. also some of those oil additives that bond to metal may help as well. It will help keep things at least a little lubricated during start-up.

did the air temp sensor swap help at all?

 

 

Car does not have wires as each cylinder has its own coil.


Using 5w30 full synthetic oil.


Need to figure out which cylinder is misfiring.


WIll try swaping mass air flow sensor and see if that helps.


Thanks

 

in that case, have you checked the wires leading to the coils to make sure none are frayed? also, if you think it may be a coil that giving you problems, try disconnecting one at a time until there''''s no difference from normal. then you''''ve found the bad one. This is not an approved method (I don''''t know if it will hurt anything, but it might). The best way would be to have some place test each coil with a tester - preferably cold, since it seems to work fine once it''s warmed up a bit.Edited by: slymer