325e probs

[cheapestcar]

So, I have a 2/86 build 325e. The guy before me replaced the "cps". I say cps because it is the sensor in the very front of the engine. No toothed wheel. I can see 2 sensors on the transmission housing.
What is the sensor at the front of the engine(under the distributor, in the position of the cps in the later years).
Car stalls intermittently and misses frequently. Thinking replace the bell housing cps. What is the very front sensor?

[tomstin]

On my 85 E, the front sensor is the TDC sensor which goes to the diagnostic connector. There are two on the transmission bell housing, one the is reference point sensor (once a revolution). The second is engine speed sensor which senses flywheel teeth. These two can be checked with an ohm meter but if they are flaky (intermittent) you may get a false reading.

If you decide to replace them, do it one at a time so you don't get them mixed up!

[cheapestcar]

On my 85 E, the front sensor is the TDC sensor which goes to the diagnostic connector. There are two on the transmission bell housing, one the is reference point sensor (once a revolution). The second is engine speed sensor which senses flywheel teeth. These two can be checked with an ohm meter but if they are flaky (intermittent) you may get a false reading.

If you decide to replace them, do it one at a time so you don't get them mixed up!

I thought the lower one was the crank position sensor and the other was for diagnostics. In any event, I'm going to replace the lower sensor (crank position sensor). Not sure what to do about the TDC sensor. Replace that too? Like I said the guy before me assumed it was CPS and replaced it with a CPS (from later years it was the CPS).

Appreciate the help, thanks.

[tomstin]

As I understand, the TDC sensor is only used when you have the tool plugged into the diagnostic port. Looking at the wiring diagram it only goes there and no further.

[superj]

Yup. The transmission sensors are the drivers for the eta motors. Those two sensors usually do a complete fail, not intermittent.

Check the afm for a groove worn in the wiper plate from the arm contacting the same area for 30-40 years of use. That's a very very common issue and will cause issues like you have. Also, unplugging and repluggin the afm in can sometimes help cure the issue for a while because of dirty connections