E30 M3 not running with blue coolant temperature sensor

[jerryhopson]

Hello,
I'm really excited to find and join this forum because my 1988 E30 M3 is having issues. It won't run with the blue coolant temperature sensor plugged in, yet overfuels when it's unplugged. Vehicle ran fine before.

Crank sensors have been replaced. Air mass meter tested okay. There is no air leaks on inlet.

Hope that someone can give me some advice! Thanks in advance

[82eye]

Hello,
I'm really excited to find and join this forum because my 1988 E30 M3 is having issues. It won't run with the blue coolant temperature sensor plugged in, yet overfuels when it's unplugged. Vehicle ran fine before.

Crank sensors have been replaced. Air mass meter tested okay. There is no air leaks on inlet.

Hope that someone can give me some advice! Thanks in advance

ok. pics of said m3. i just wanna dream and be jealous ....

blue temp sensor typically supplies coolant temp data to the ecu which effects the fueling map. that's all i can add. you probably knew it already. if it's bad or the ecu konks on that link there will be issues.
also a smoke test is a better idea to check and eliminate vac leaks so maybe that's two lol. both are pretty generic places to start on any e30.

there will be other guys with real experience on s14s post soon.

[reelizmpro]

It's a variable sensor so the hotter the coolant temperature, the lower the resistance. You need to measure the resistance of the sensor. It should be around 1300 ohms or so around 70 degrees (engine cold) and goes down to about 250 or so when the engine is hot. If you get higher values (2500-10k+) the DME will just keep dumping fuel in to the point the engine floods and you will have to clear it each time. I even encountered a situation where the old sensor failed and the new Bosch sensor also failed right about of the box (I didn't bother testing it). You also want to make sure the wiring is also in good condition as well.