Hi guys I have 94 z28 thats stock except for cold air intake and exhaust. For the last couple days my car had been idling real rough at a stop light but as soon as I hit the gas its completely fine. Also it has almost died on me at a stop light today, the lights dimmed and the battery level went super low, but again as soon as I hit the gas everything was fine. That's part 1 of the problem. Second part is that it heats up super quick when I'm not driving on the highway. When I'm on a side road the temp gauge will go up and down for a little bit then once I get going for a minute is cools back down to normal temp.

So to sum up on the highway its completely fine, at stop lights it idles real rough and it struggles to stay alive, it usually goes up in down from 700rpm- 300rpm (unless i put it into neutral then its okay). Then when not moving it heats up super quick until I get air flowing into it from driving. Today I noticed I have a slight coolant leak from a hose right about the opti spark; I've read other forums saying a coolant leak could of leaked into the otpi and mess it up. I'm thinking that is maybe the problem? And the running hot problem may be from the slight coolant leak. I did replace the opti spark in November of 2017 after the car kept dying randomly on me and replaced the ICM at the same time.

Any help would be great, thank you!

 

Get the alternator checked and verify your battery is good

 

Get a volt meter and check the alternator while it's running. It should read at least a steady 14.5 to 14.7 volts. If it's fluctuating or less than that 14 volts then the alternator is no good. As far as the heating thing, where does the needle end up when you say it's hot? Do you hear the radiator fans?

 

 

 

Define overheating? Is the temp gauge pegged or close to it? Your fans should come on without the use of A/C (I believe) at 228* for primary and 235* for secondary. Don't quote me on that. Not 100% positive.

 

 

There is a bleeding process you should follow before starting the engine, which involves the bleeder screws on the thermostat housing and heater hose.

http://shbox.com/1/4th_gen_tech2.html#radflush

 

 

No idea. Perhaps a short in the circuit. You should still let the coolant system pressurize and loosen the bleeder screws to ensure there's no air in the system.