Hard Cold Starts on '89 3.8L
O.P
09-05-2003, 07:42 PM
My bonneville has a real hard time starting when its cold. It kinda coughs and wants to start, it takes a few of these coughs before it fires up. Then once it briefly starts, it dies. As I attempt to start it again it might cough a little then run a little longer. Finally by about the 3rd or 4th time it gets better. Once it is warmed up it runs great and starts great, but after sitting a few hours, its is the same cycle. I've replaced O2 sensor, camshaft pos. sensor, TPS, Sparkplugs, wires, fuel pump, fuel filter. I have also let the car sit overnight and check the fuel rail the next morning and it seems to maintain sufficient pressure when i release the fuel valve. Any ideas?
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GMMerlin
09-06-2003, 02:40 AM
The is an old tech bulletin on cold start stalls with these engines.
Most likely cause is a faulty IAC valve, If I remember right the part number for the new valve is a 17112650
Most likely cause is a faulty IAC valve, If I remember right the part number for the new valve is a 17112650
O.P
09-06-2003, 09:45 AM
Where is the IAC valve located? Is there a way to test it and can you tell me where I can find the old tech bulletin dealing with the same problem.
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GMMerlin
09-06-2003, 11:24 AM
The bulletin # is 93-t-04
The IAC valve is located on the throttle body. It is round with 2 screws holding it to the throttle body and has a 4 wire connector.
The best test for that problem is to scan IAC counts with a scan tool...the counts will be different each time you start and let the car idle.
The IAC valve is located on the throttle body. It is round with 2 screws holding it to the throttle body and has a 4 wire connector.
The best test for that problem is to scan IAC counts with a scan tool...the counts will be different each time you start and let the car idle.
O.P
09-10-2003, 03:11 PM
Wow! I'm impressed. This car has given me hell for the last two years with the same problem. I have done all sorts of things to it EXCEPT for the IAC. Well, I must say that you are on the right track GMMerlin. I pulled of the IAC and it was stuck closed with ignition on and off. I cleaned it with carb cleaner and it began to move in and out. The car starts a hell of a lot better, it will start immediately, but it still turns off when i gas it. It does this twice before it stays on. It is giving me a service engine code 14 (CTS). I have replaced the CTS twice and the thing that i have noticed is that the car will fire up right away after i replace the CTS, but then the service engine light comes on and it continues with the same difficult starting problem. Am i burning out the CTS or is there a reset (I unplugged + batt for 10 min). Nonetheless, it does start better, but i want it perfect.
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GMMerlin
09-11-2003, 07:09 AM
the problem may not be the coolant sensor, but the wiring or ecm.
The coolant sensor is a 2 wire sensor..if memory serves me right, the wires should be yellow and black.
Check the service number on your ECM..if it is a 1228253 (or the last 3 digits are 253) replace it (perferably with a GM part). We had a lot of problems with that part number ECM and GM did an excellent job with coming up with a remanufactored one to replace it. (I dont trust aftermarket ECM's)
The coolant sensor is a 2 wire sensor..if memory serves me right, the wires should be yellow and black.
Check the service number on your ECM..if it is a 1228253 (or the last 3 digits are 253) replace it (perferably with a GM part). We had a lot of problems with that part number ECM and GM did an excellent job with coming up with a remanufactored one to replace it. (I dont trust aftermarket ECM's)
O.P
09-12-2003, 12:49 PM
The ECM has already been replaced. The Temp sending unit is a 2 wire and the CTS is a single wire. Both of these have been replaced. How many volts or ohms should be in the CTS wire?
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