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Starter or battery?

Discussion in 'E34 (1989-1995)' started by slinky66, Jul 30, 2008.

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    slinky66

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    Yeah, It sure feels like I'm chasing a ghost as well. I'm having fun through the process however. In the Bentley's manual for my car, there is a troubleshooting section that suggests testing the coil harness terminals if the car will not crank so that's why I did that. I will test injection pulse and then crank position sensor next. Would a bad crank position sensor cause no spark? Thanks as always for your help with this
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    mooseheadm5

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    Well, you may be doing your testing incorrectly. Definitely verify that the meter shows 0 ohms when you touch the leads together. I believe that they want you to test the internal resistance of the coil packs, but will have to check the bently manual tomorrow.

    A bad crank position sensor, as I said, will cause no spark and no injection pulse. Sometimes it fails totally, sometimes intermittently. It is the only way the ECU knows that the engine is running. The camshaft position sensor can cause problems here, too, but usually it will run even if it is bad. Test procedure is the same for crank position sensor as it is for cam position sensor.
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    mooseheadm5

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    Yes, you were definitely testing it incorrectly. You need to test the primary resistance of the coil as outlined in the manual but putting the ohm meter on the terminals of the coil itself.
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    slinky66

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    Cps E34 M50

    Yes, much better... 0.8 ohms on each coil terminal (15 and 1) Thanks for clearing that up. I have been trying to locate my crank pos sensor and cannot. I removed the hose attached to the intake and looked under the intake manifold but could not find anything. The Bentley's also has a picture of the cps but only for an E34 M20 engine - I have an E34 M50, which does not look much like the M20. It goes on to say that the cps is attached to the front of the engine on a toothed wheel on the front of the crankshaft. Don't see that either although they could be referring to an M20 engine here as well. Help! I am going to get my baby started no matter what!
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    mooseheadm5

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    slinky66

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    That's a great website. Thanks. I'm pretty sure I have to remove the radiator shroud and fan blade to access the crankshaft pos sensor, which sounds like it's really close to he water pump. The 32mm nut that secures the fan to the shaft is rusted and when I try to loosen, after a shot of wd40 (clockwise, left-threaded nut), the housing around the nut also moves so I cannot remove the fan blade. What is the secret? Bentley's mentions a tool BMW makes for this very problem..Thanks
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    mooseheadm5

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    Ground thinner Craftsman 32mm wrench, big hammer. It takes a shock to release it, usually, but you have to be careful how you swing!
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    slinky66

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    Thanks! Will try this weekend...Not familiar with the term "Ground thinner". Some type of solvent for loosening up the nut?
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    mooseheadm5

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    Nope. The craftsman wrench is too thick, so for it to fit between the fan and the pulley, you have to take it to a grinding wheel to make it thinner. The other choice is a more expensive but less work thinner 32mm wrench.
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    slinky66

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    OK, I got the fan and shroud off revealing the crank position sensor (see image) Looks like it's seated into the tooth with a hex bolt? Any idea what size or range of sizes I should get in order to loosen the bolt? My Bentley's does not specify for this particular repair.

    Also, do you know where the other end of the CPS connects to? Once I loosen the end attached to the tooth, I'll need to find the other end! I want to make sure I do not take more of the car apart than necessary! I can visually trace the wire for about 3 inches then it disappears and also is very tight.

    I don't know if I mentioned that the check engine light is not coming on. Forgive my ignorance but Is it possible to have a faulty sensor like this go undetected? Could this be as simple as restarting the ECM by unplugging the battery for an hour?

    Thanks as always!
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    mooseheadm5

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    It is 5mm hex. You will have to follow that wire under the intake. You will need to remove the airbox and mass flow sensor to gain access. You may need to remove the intake boot. I cannot point out exactly where it plugs together with the harness, only that it does so under the intake somewhere around cylinders 2 and 3, if I am not mistaken. Yes, it is possible, because when the crank sensor does not work, the ECU kind assumes the engine isn't turning. A code exists for it, but I have only very rarely seen one actually get stored in the ECU. Good luck.
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    slinky66

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    Crank Pos Sensor will not budge

    I found the location of the crank pos sensor terminal and decided just to replace it. I bought a Hella OEM replacement. I removed the 5mm hex nut but the old cps will not budge! I don't want to mess up the toothed wheel that the cps is touching so I would love to know how I should go about dislodging the cps.

    As always, thanks for the help

    Jeron guest

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    The toothed wheel is not very delicate, but I wouldn't pry against it with anything metal. Try spraying the CPS with Liquid Wrench or PB Blaster then tapping on the CPS with a "hammer" to loosen it.
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    mooseheadm5

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    Also try twisting it in addition to Jeron's suggestions.
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    slinky66

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    Crank Position Sensor Replaced - Problem solved!

    I used PB Blaster to loosen the old CPS. After some twisting and light tapping, I was able to remove it. I then replaced it with a Hella CPS.

    Car started with no problem - Have driven about 20 miles so far with no issues. Thanks again for all of the help and guidance on this project.

    Jeron guest

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    Congrats!

    The CPS is the cause many Phantom No Starts.
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    slinky66

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    Hella CPS failing?

    I installed a new Hella CPS about 1 month ago and everything has been fine. I tried to start it up this morning and it appears that I am having the same exact problem. Is it common for a CPS to be fine and then after a month fail? Just curious. What is the procedure for testing the CPS with a multimeter? I am assuming that I need to test the terminals on the Hella side of the CPS correct? Thanks!
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    mooseheadm5

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    Test it like that from the plug on the Hella side, as you say. It may not be the CPS, but testing it while it is definitely not starting is a great way to find out.

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