I have just finished installing a fresh lt1. I have a new factory gm opti and factory wires installed. In fact the engine is all stock except for .030 over and cai.It starts fine idles about 1500 then drops down to about 1000(which seems high to me). Excellent power and driveability. However after my 3rd. test drive (after topping off and bleeding coolant system).After car warmed up it started to just completely cut in and out. With no warning lights. I pulled into a parking lot and inspected obvious wire plug ins/connectors no problem found. Started up, started fine and didn't seem to cut out. Then just before I got home same problem, service engine light amber light illuminated this time. Its like its completely losing ignition/spark. Any ideas? Its a 95 6 speed. Also I have no scan tool. From what I read you can only jumper the 93-94 12 pin style obd connection, to get codes. Can I jumper a 16 pin connection for check engine light code flashes? Or do I need a scanner? Any help appreciated...

 

Not sure if its the same with the LT1 as with it is LS1 but i do know LS1 starts up on Open loop until cats warm up then go's to closed loop and the PCM strives to keep AFR at 14.7:1 (stoich). Sounds like your car starts up fine because it is in open loop and feeds itself to stay running then when cats warm up and go's to closed loop it almost dies perhaps due to the Long term fuel trim being incorrect, you can try to force a pcm relearn by disconnecting battery for like 10 min and then rehooking it up and starting car and do a few drive cycles. If that didnt work take it to tuner and have them check your fuel trims at idle.

 

I went and bought a actron 8145 scanner. It had a stored code of 15 which is coolant temp sensor. I cleared it and ran the car with the scanner hooked up. Once it warmed up the car started cutting out again. The scanner captured code 15 again and the coolant temp was displaying -40 deg F(on scanner). I changed the temp sensor(on water pump) and its running great and hasn't faulted again. I put a ohm meter on the removed sensor and warmed up the end of it in a soup can with water and a torch. It's checking fine resistance wise. So I am wondering how that fixed it. I checked the wires at the sensor. Lighter colored one read 5volts dc with key on and other has good ground. Perhaps the sensor is shorted when its screwed into the water pump? Anyways Its running flawlessly now and I have a new tool in my toolbox

 

Awesome!

 

You should have bought a cheap laptop and a cable. That way, you could log/monitor your sensors and check and clear DTCs. You could also start tuning if you wanted. It's a great tool.