So My car is weird. Scenario 1: Some times it fires right off and starts great other times it will half start and act like it doesn't want to but will eventually after like 2 seconds come to life and fire right. Any ideas? It only does this occasionally when warmed up. have never had it happen cold after sitting all night. usually after shutting it off and it sitting like 20 to 30 min. Scenario 2 : Also I don't know if this is normal but it likes to idle high sometimes after sitting for the same period of time and then after like 20 sec drops down to normal idle. so example in Scenario 1 I drive 20 miles to town to walmart go in shop for 30 min to at the most an hour come back out and it will either fire right off or do the slow start. And with Scenario 2 It will start and idle around 1000-1200 Rpms for like 30 sec then slowly come back down to 6-700 Rpms. Any Ideas?

 

Hello,

I would start by checking out the sensor that tell your Cold Start Injector (CSI) to come on. If the engine is seeing an incorrect value then it might be using the cold start injector when the engine is warm. When the cold start injector is running the extra fuel might push the RPM's up while the cold start system is operating and after its shutdown your idle returns to the normal value.

In the old days of Carburetors I would say that your Electric Choke is out of adjustment as it sounds like what you are describing. This Cold Start system on the L98 engines works to do the very same thing as the old choke plate and its controls.

It seems that when the temperature sensors mounted on the engine fail that starting issues start to appear. If the engine sees a sensor indicating that the engine is warm it will not use the CSI. If the engine thinks it is cold or cool enough it will try to use the CSI to assist in starting by adding additional fuel to make it run.

There are two temperature sensors on these cars, one for the gauge and one for the Engine controls. The one that supplies info to the Computer is likely faulty or it could be the one that is connected to the cold start system, I am not sure if the CSI has its own sensor or whether it used the engines temperature data that is fed to the computer.

To test this idea you can unplug the CSI power connector and try to see if you still have issues. If you do not have any more trouble then it is a bad temperature sensor telling the engine erroneous information. There are procedure to test the CSI and the temperature sensors in the FSM.

I hope this little bit can help you. Have a great day checking out your Corvette!