I have been trying to figure this out. My '89 350 TPI will not idle by itself when started cold. I need to rev it over 1,500rpms until it for a bout 30 seconds or so. Sometimes it will die when cold also.

I wonder if the IAC could be causing this? It is pretty new. Once it is warm/hot, the car will restart fine.

Any ideas? Could the initial timing set at 9 degrees cause this? No trouble codes come up either.

I am stumped.

 

Throwing any codes?

 

i would check the cold start injector, u still use that right?

maybe redo the tps and iac adjustments to be safe.


https://www.thirdgen.org/newdesign/tech/tpimod2.shtml

 

does your coolant gauge work? if not maybe your coolant temp sensor is no good. this is what was wrong with my car and i had the same exact problem.

 

Cold start only functions when cranking.
I like the CTS Idea.

Also get some FI cleaner and put the red nozzle in the little opening between the throttle blades and douse with cleaner. then let dry and start car.

also could have vacuum leak.

 

No trouble codes come come up.

The car is post-cold start injector.

I never though about the coolant sensor. It does work, but could be sending weak voltage at startup?

Hmmm....I have all winter to figure this stuff out.

 

MAke sure your ect is reading correctly, should match the mat readings when cold in am(or be very close at initial startup), it can be a little out and read richer than actual...

Injectors being bad/plugged/leaking can also show up more so on cold starts as well due to excess fuel being present , u can ohm them out for a quick check usually somewhere around 15-17 ohms when stock, they should all be very close either way...

Make sure that your TB is clean and that your TPS and IAC are set correctly as well because they could do almost the identical thing
LAter
JEremy

 

Please bear in mind that the sensor for the gauge in the dash is NOT the same one the computer pays attention to. (temp) a failing cts would indeed cause some interesting problems, but, normally when they fail, they go open. (coolant temp -40* C, talk about flooding.....)

Make sure the rest of the system is in good shape, tune-up, etc. and do the basic maintenance to the TB. should fix ya right up.

 

Interesting. Looks like I will start by replacing the CTS first. I did have an SLP stage II chip that I removed and put the stock PROM back in. Maybe the ECM has not relearned the settings in that area yet.

 

Yeah like I said it wound up being the CTS for me. I started by changing the TPS which wasn't in great shape. That wa not it so I did the IAT relearn thing. That also was not it so my buddy told me that it was probably my CTS. So I changed the one on the side of the motor and the one on the manifold. He is pretty damn smart and I usually ask him when I can't figure something out. Well turns out he was right on the money. The car was running pretty good and my gauge works again.