need help with 95 G30 van idle problem
 

1995 Chevy Van 350 V8 2wd Automatic with approx 11500 miles

I got a motorhome which is based on a 1995 chevy g30 van with a 350 engine. It was working perfectly before I parked 2 months ago. 2 weeks ago, when I try to take it out, It starts and ran a little rough. The idle speed feels low. However, I was still able to drive it. It stalls a couple of times at stop lights. I was able to re-start and drove it home. The next day, it still starts but unable to idle. It will start and run for about 10 seconds then stalls. If I keep my foot on the gas pedal and pump it, I can run it for as long as I want. No check engine light. Same problem regardless engine was cold or warm. I tried a few things like checking all the vacumn hoses. replaced IAC, drain old fuel, replaced fuel filter, clean injector with seafoam with no luck.

Here what I have found....
If I unplug the connector to the coolant temperature sensor, then it will start and idle fine. However the check engine light will come on.
Thinking it has a bad coolant sensor, I replaced it with a new one but didn't fix the problem. If leave it un-plugged, it starts and idles ok. While the engine was running, as soon I plug it in, the engine stalls immediately. What do you think is wrong? Where should I look next? Where can I find information on how coolant temperature sensor affect engine function? Thanks in advance for your help.

Do you fix the problem? I have the same issue

well , first , never unplug /connect ANY of the ECMs sensors while the engine is running . thats how you fry parts . second , after you have everything back together , start it . let it do what it s gonna do . thirdly check the codes, or better yet hook a scan tool up to it and read some live data . see what is got to say , and go from there .

No CTS signal keeps it from going into open loop. If the check engine light wasn't on before there's no codes set in it save the one you may have created.

This is going to be an OBD-1 vehicle so nobody has a scan tool that will read it.

I would try checking the fuel pressure, perhaps the fuel pump is starting to fail. Should be about 15 PSI. No test port on these engines, so you'll have to disconnect a fuel line at the TBI unit.

For just pulling codes all it takes is a paperclip. For a scan tool I made one from soldering up a few things on a diagram I found online and used a serial to USB adapter and free software. I might have tossed it as I don't have that old S10 any more. I bet someone still has the info... I might be able to dig it up if anyone is interested.

That's a 1 wire temp sensor? Did you use Teflon tape? If so pull it off and use liquid thread locker because it needs to ground. You can check by grounding the body of the sensor.

I hope you all realize you're responding to someone that hasn't been here in 5 months.

this one was 13 years ago

closed loop

I always mix up which loop is which name.

Need to set old threads to auto-lock or give a warning that it's old before letting people post

that's a good idea