Question about Crank Position Sensor

[Dave M]

So I thought I'd fixd my M50 stumbling/stalling issues. Guess not. Yesterday (two days after coming out of hibernation), it stumbled at low to mid rpms for quite a while and then finally stalled. It would try to start, but quit immediately. I finally got it running after about 15-20 tries (I'm in the middle of the road :D ). Then I stumbled my way home. I thought it could be the TPS, so I removed it and drove slowly for a while, then it continued to stumble so I concluded its not the TPS. Reasonable asumption?

I am aware that the CPS will cause a no start, but can it also cause an engine to cut out periodically and or stall?? I removed it this morning and tested it. I could not get the ~1280 ohm mentioned in Bentleys. My reading was ~450 ohm and only between two of the three terminals. The wire also spins at the sensor end and is slightle damaged at the terminal end.

As some know, I've been working on this problem for a while now and have either swapped or tested:

TPS
ICV
Coolant and engine temp sensors
Air temp sensor

As well, vacuum leaks are not an issue and the plugs/coils are fine.

Sorry for the diss-jointed post. Any help would be appreciated. I'm ready to call BMA to order a new one.

Dave

[bmwrp8]

that is the exact simptoms I had in my m20...its the CPS..you may want to check the fuel pump also

[Dave M]

that is the exact simptoms I had in my m20...its the CPS..you may want to check the fuel pump also

Actually, its interesting you bring up the fuel pump. I had a corroded connection for the power source to the pump, which I fixed, and figured I had solved the problem.......not so.

So, your M20 would not only fail to start, but also stumble when running? I sure hope its the same thing. Thanks for your experience and response.

Dave

[aquapool]

Just replaced mine on an m30. Exact same symptoms. Started sputtering, then would take 10-15 tries to start, then nothing; no start. I replaced the ICV, and fuel filter then I realized there was no spark when I pulled the plug. coil tested fine. CPS tested 0 ohms. The CPS bolt was loose causing it to hit the timing gear and that is what I believe did it in. $92 at BMA parts and she started up quicker than she ever has. Idle is smoother now; ICV probably helped. On mine because of the bad CPS the computer would not let the coil ground out. With ignition on 0 volts to coil unless you ground the volt meter elsewhere like a body panel.

[bmwrp8]

Actually, its interesting you bring up the fuel pump. I had a corroded connection for the power source to the pump, which I fixed, and figured I had solved the problem.......not so.

So, your M20 would not only fail to start, but also stumble when running? I sure hope its the same thing. Thanks for your experience and response.

Dave

I hope they're the same...that's exactly what happened to me sometimes it would take up to 8 cranks to start then while on the go sometimes it stumbles sometimes while driving it just dies then max of 10 cranks before I get it to start.then finally when I was on my way to my mechanic it died and didn't start just cranked...luckily we had an idea what the problem was...had to take a cab to buy the CPS then changed it in the road...then we checked the fuel pump just to make sure dang the pressure was normal but when we took out the pump it was cracked on top just like you opened a can halfway with a can opener!hehe my mechanic coudn't believe what he saw he said it was his first time to see a fuel pumped craked!:D anyway whats your current km.reading in your e34??saw your 500,+++ damn!where have youve been going?to the moon???:p :D

[ryan roopnarine]

the crank position sensor value in the book is wrong dave. i don't know where my bentley is right now but if you type in the values (and +/- percentages) given for all 4 engines i'll tell you which one is right

[Dave M]

Thanks guys. I'll ordering a CPS as we speak. Ryan, the Bentley shows ~4XX or so for M20 and M30 engines and ~12XX for M50 and M60 engines. My resistance might be OK, but something might be chewed in the wiring as its so bloody intermitent. I'll let you guys know what happens.

[ryan roopnarine]

the lower m20/30 ones are the same value as your m50 one then.

[Dave M]

Well, I'm getting 515 ohm (acceptable), but only between pins 1 and 2 (only pin #'s 2 and 3 are labeled. However, whether or not this is OK may be meaningless if the wiring is FUBAR.

Thanks again Ryan.

Dave

[RobPatt]

what clearnace should there be between the sensor and the crank teeth?

[The Bigfella]

Clearance - an air gap.

The plug on my pulse generator disintegrated as I was putting the M5 engine back together. I insulated the terminals and its done 2,300km so far - with a new one on the way from BMA.

The quote from BMW Australia was the equivalent of US $525 - more than five times the BMA price.