Cold run problem
Thread Starter
1st Gear
Joined: Nov 2013
Posts: 1
Likes: 0
Cold run problem
1985 corvette 350 automatic. Has a 192,000 miles on it. The car starts perfect everytime, but when you give it gas it conks out. Hit the key it starts right up again, give gas it conks out again. However, if I let it warm up for 15 minutes the car runs great. Have changed out plugs, wires, cap, rotor, and mass air flow. Does anyone have a solution to this problem? My tech has run the scanner on it and no codes come. Any help would be greatly appreciated. It is driving me crazy!
Safety Car
Joined: Aug 2009
Posts: 3,752
Likes: 278
From: Melbourne, Victoria, Australia
Have you checked the TPS throtte position sensor voltage? should be 0.54 volts dc (measure middle and top wire) multimeter probes can be pushed in the connector.
Should be 0.54vdc to 4.5 volts wide open throttle, check the voltage ramps up smoothly. The computer needs to see throttle percentage to deliver the correct fuel load. (although its ok when warm i would still check it)
The 85 has a cold start injector but that only activates when engine is started from cold, the temp sensor for that is at the front/middle of the engine in the inlet manifold. Check that is connected and the cold start injector connector is fitted properly (on driver side of engine between cylinders 3 and 5 on the inlet manifold)
Should be 0.54vdc to 4.5 volts wide open throttle, check the voltage ramps up smoothly. The computer needs to see throttle percentage to deliver the correct fuel load. (although its ok when warm i would still check it)
The 85 has a cold start injector but that only activates when engine is started from cold, the temp sensor for that is at the front/middle of the engine in the inlet manifold. Check that is connected and the cold start injector connector is fitted properly (on driver side of engine between cylinders 3 and 5 on the inlet manifold)
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
Check the idle speed when the engine is first started. If it's below 1000 RPM then you probably have a bad CTS (Coolant Temperature Sensor), connector or wiring problem. There are two, one for the dash and one for the ECM. The ECM CTS is located on the front of the intake manifold under the throttle body. If the ECM thinks the engine is warm it won't richen the mixture and it will run the engine at a lower RPM. It should "fast idle" when cold like back in the carburetor days.
