91 lumina apv overheating

[knuckle ears]

Have overheating problems today. Seems like the rad fan will not come on.

was on the highway and started to hesitate and then the motor died. looked under the hood and antifeeze all over.
filled up the rad again and took the thermostat out. didnt over haet anymore but the fan still wont come on.

I found the fan relay and tested and it works. removed the engine coolant temperature sensor and tested it with an ohm meter in hot water and ice cold water. the readings were according to the book but still the fan wont operate. Also took the fan out, oiled the bearings and pushed the relay contacts in and the fan runs.
Rad is now full and temp guage goes up to 125 degrees C.

any help would be appreciated. 3.1 engine

[knuckle ears]

Just wondering if I have the right engine temp sensor. i checked the one on top the intake manifold by the thermostat. Is this the same one that turns on the fan and or relay?? or is this the one that sends a signal to the pcm??

[knuckle ears]

Originally Posted by knuckle ears

Just wondering if I have the right engine temp sensor. i checked the one on top the intake manifold by the thermostat. Is this the same one that turns on the fan and or relay?? or is this the one that sends a signal to the pcm??

I took the trouble codes and they read 14 engine temp sensor over 275 degrees and code 34 MAP sensor low air flow.

when I jumped the A and B terminals inside at the DTLink to get the codes the rad fan came on. The engine was hot at the time. the relay and fan work but wont come on when driving. What does this mean?

Engine idles rough and is hard to start now after the over heat. I have to put the gas pedal to the floor and then it will start. also seems to use more gas.

[LMP]

Jumping terminals A and B does make the fans run. Same on mine.
Temp sensor near thermostat is the CPU sensor, and the CPU turns the fans ON and OFF based on this temperature.
ANy overheating problems with the 3.1 lets one think of failed head gaskets....was that story already played with yours? ANy disruptions in the heat delivered by heater?
DTC34 is HIGH vacuum...(thus low throttle opening) in condition where higher throttle opening (TPS ) indicates vacuum should be lower. Turns to default mode nad uses TPS alone for fuel metering.....possibly explaining the variation you noticed in gaz mileage.

[knuckle ears]

Originally Posted by LMP

Jumping terminals A and B does make the fans run. Same on mine.
Temp sensor near thermostat is the CPU sensor, and the CPU turns the fans ON and OFF based on this temperature.
ANy overheating problems with the 3.1 lets one think of failed head gaskets....was that story already played with yours? ANy disruptions in the heat delivered by heater?
DTC34 is HIGH vacuum...(thus low throttle opening) in condition where higher throttle opening (TPS ) indicates vacuum should be lower. Turns to default mode nad uses TPS alone for fuel metering.....possibly explaining the variation you noticed in gaz mileage.

No didnt have any head gasket problems or heat delivery problems from the heater.
The engine worked top notch until then.
I checked and cleaned the distributor cap and rotor and it started to idle and start a bit better but something still isnt right.
it idles rough when in gear at a light and tends to stumble on takeoff.
Antifreeze has't gone down but I only drive it to work daily about 15 minutes each way.

[knuckle ears]

Originally Posted by knuckle ears

No didnt have any head gasket problems or heat delivery problems from the heater.
The engine worked top notch until then.
I checked and cleaned the distributor cap and rotor and it started to idle and start a bit better but something still isnt right.
it idles rough when in gear at a light and tends to stumble on takeoff.
Antifreeze has't gone down but I only drive it to work daily about 15 minutes each way.

I am going to do a compression test on it tomorrow.

I also removed and cleaned the IAC motor which was carboned up. I cleaned it and put it back in and it starts and idles better. i am hoping that if the compression test looks good that maybe it just got glogged up with overheated gunk/carbon and whatever????
I will let you know.