Allrighty...

this is a nagging problem in my gf's car. its a 305TPI, 89 trans am with a cam. it has a 5 speed conversion in it.

when the car warms up, it will try to die - and will stall out. the problem is intermittent, it doesnt do it all the time or at a specific temperature. its really driving me nuts. the SES light will come on and go dark as the engine misses. you have to pull the car over and let it cool off before driving again.

my mechanic replaced the distributor/cap/rotor/wires and replaced the cooant temp sensor. both times got the car back as "fixed" but the problem still exists. today, on the advice of one of my buddies, after the car got hot and started jerking, i pulled the plug on the coolant temp sensor. it didnt seem to be jerking around as bad as it was (undriveable), but it wasnt running very good either. i didnt get enough good drive time in to determine if it will run "ok" and if the coolant temp sensor is the problem.

the car is throwing a code 15, but that was only today when i had the sensor disconnected. is it possible my mechanic put in the wrong CTS (car is an 89 but engine is earlier)? what else that could be causing this problem?

 

Which coolant temp sensor did you pull? There is 3 IIRC. One is a gauge, one for the fan, and one for the ECM.

IIRC, the one on the pass. head is the one for the fan. Cant fully remember which one the other two are.

 

dave, the one for the ECM is under the throttle body on the front of the intake.



ive been searching the board for similar problems and so far ive found solutions of:

bad o2 sensor
https://www.thirdgen.org/techbb2/sho...coolant+sensor

bad coolant temp sensor (mine is new, but could still be bad)
https://www.thirdgen.org/techbb2/sho...coolant+sensor

EGR
https://www.thirdgen.org/techbb2/sho...coolant+sensor

Fuel Pump (mechanic tested and said it was good)

Ignition/bad pickup (new distributor as stated above)

bad chip



i hate to just keep throwing parts at this thing until i find the problem, especially since i have to drive it for awhile to get it to act up - when means if the problem doesnt get fixed, i'm more than likely stranded for awhile.
my friend with a laptop & scanning software wasnt able to get his system to work on the car, it wouldnt connect. so i cant even ghet him to scan it for me.

 

c'mon fellas, anyone have a direction for me to go in?

i took out my multimeter and the CTS appears to be giving proper resistance. it is also getting its 5 volts.

also another hint for anyone with ideas, my mechanic did mention that he felt the car was running awfully rich...

 

Aquire a scan tool such as Auto Xray. you can see what the car is doing while runnig without removing the sensor, especially since some sensors can cause the same problems. then it becomes easy to solve your problem.

 

Two problems that occur when the engine gets hot are the ignition module and the injectors. Check the injector resistance with an ohm meter. They must be between 12 & 16 ohms.

Don't know of any check for the ignition module. Just R&R if you have one around. Can also be the distributor pickup coil.

Do the tap test on both the MAF & the ECM. They too can cause problems such as you have.

RBob.