Author Topic: Temp sensor question, (Read 3906 times)

D. Clay · « **on:** September 02, 2007, 08:36:10 PM »

How do I tell if I have the temp sensors in the head connected to the right wiring harness plugs. My temp gauge read low after putting it back together. It ran real rough and sputtered when I opened the throttle for about 2 minutes and then smoothed out. Temp gauge did read 1/2 at temp and now reads 1/4. Realoem shows different part numbers the sensors. I'll switch them tomorrow if I can get to them under the intake. Anyone know about this and also if they are accessible without disassembling the whole car again.

D. Clay · « **Reply #1 on:** September 03, 2007, 03:53:02 PM »

Answer to my own question. I switched the connectors and the temp gauge reads as before and the check engine light went out. Motor runs smoother but It seemed to have a little more power before. I think because it was leaning out the mixture. You can get to the sensors under the intake but it's a PITA and I lost another of the little metal clips.

bmwman91 · « **Reply #2 on:** September 03, 2007, 05:19:44 PM »

Glad to hear you sorted it out. I thought that one had a 2-pin connector and the other was a single though? Agreed on the PITA to get to the inner one. What a royal pain!

D. Clay · « **Reply #3 on:** September 03, 2007, 09:27:51 PM »

They went on and snapped. Like an idiot, it never occurred to me to look inside at the pins. What do you think about the perception of a bit more power from leaning the mixture? It seems it would have more to do with the air temperature than head temperature.

bmwman91 · « **Reply #4 on:** September 04, 2007, 09:46:58 AM »

These motors seem to run fine up to ~17:1 under lighter loads. At WOT the M42 can hit 16.1:1 around 3000RPM, and that seems to be the way it is tuned.

As far as overall power gains, I am not really sure how well the M42 responds to mixture changes. Tinkering with the AFM thermistor is one way to make small changes.