Author Topic: How to check cam/crank sensors????  (Read 11160 times)

longms

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How to check cam/crank sensors????
« on: January 12, 2010, 09:56:02 AM »
My car abruptly died when I stopped at a light yesterday and have been searching high and low about this problem and everything is pointing me towards these sensors. I am getting 1-2-2-2 from the "stomp test." Which this code really doesn't tell you anything.

I am not really familiar with using a multimeter and checking electronics. When I pull these sensors I have gathered that the cam should read about 1200 ohms and the crank should read about 650 ohms. Where on the sensors should I be touching the leads??? Should the car be on the "on" position, should it be cranking or should the car be off? I am not sure what I am doing and am looking for some direction.

I am also checking the DME relay and am not sure what readings I should be getting and between what plugs they should be reading from. My last fear is that I have a faulty computer in my car.

I am trying to get parts ordered today and get them shipped overnight so I can possibly have a car by the end of the week. Thanks fellas.
« Last Edit: January 12, 2010, 10:20:12 AM by longms »
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DesktopDave

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How to check cam/crank sensors????
« Reply #1 on: January 12, 2010, 10:29:10 AM »
I don't totally agree with your diagnosis.  The 1222 code is an O2 sensor problem, likely from a big vac leak, faulty AFM or old O2 sensor.  Here's a good list of codes & a little good advice.  Likely as not you might have more than one problem.

I'd start with the fundamentals.  Is the car getting a spark?  Is it getting fuel?  Is there any cracks in the intake boot or ICV pipes?  Replace them or tape them up if so.  They'll stop the engine if they're too big.

Your DME is likely OK, since it sends codes.  It wouldn't light the CEL if it was dead.  Sure it's possible, but not likely.

I don't think the cam sensor can set a code if it's bad, but it's only for fine-tuning the timing...it'll make the car run rough but it should still run.

The crank sensor will stop the car but not set a code at all (you'll get a 1444 normally, the all clear code).  The fuel pump will not run but the engine will turn over.  If the crank sensor doesn't have enough resistance it can't send a clear signal to the DME/ECU and the DME locks out the fuel pump for safety reasons (it assumes the car isn't running & prevents fuel from flowing intentionally).

You can test these sensors at their connectors on the engine conduit...it's a long black metal channel that runs between the upper & lower intake manifold.  Car should be off.  You'll see the two connectors near the front of the engine (by the oil filter housing) on the driver's side.  Pull those plugs & probe them with the multimeter.  Top is the cam, bottom is the crank.  Here's a pic of the engine, look at the very top center for the two black plugs I'm talking about:
 You can see the black conduit too, bolted to the intake manifold support bracket.

I don't want to sound like a jerk, so if you know what I'm talking about just ignore all this:
To use the multimeter (or DMM) you'll have to set it on ohms or Kohms (1000+ ohms) to test for resistance to electricity.  Make sure you have the DMM plugs in the right sockets too.  Mine has a single ground for the black probe, but two for the red probe.  You have to move the red probe from one plug to another depending on the test you want to run.  On mine, like most, the high-current amperage tests are dedicated to one socket, all the others run off the other one.  You might have to learn the symbols for the tests to be sure which is correct...resistance is measured in 'ohms' and the symbol is a Greek omega. Sort of looks like an 'O' with feet.
« Last Edit: January 12, 2010, 10:44:37 AM by DesktopDave »
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longms

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How to check cam/crank sensors????
« Reply #2 on: January 12, 2010, 11:37:03 AM »
Thanks for all of this information.

Symptoms so far:

No Spark
No fuel that I smell (when I pulled the plugs)
All hoses are brand new but will give them a once over tonight.

Would a bad O2 sensor cause the car not to start at all? If the crank sensor were bad and not sending a signal would that car be able to run? My understanding is that it would not be able to run at all.

I will probe the plugs on the sensors when I get home from work. Do those numbers sounds about right when checking the sensors?
« Last Edit: January 12, 2010, 11:44:27 AM by longms »
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RED IS 91

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How to check cam/crank sensors????
« Reply #3 on: January 12, 2010, 11:47:25 AM »
You need to get the bentley manuals to work on these cars............



Below is a link to no start issues and testing of the cps.
good luck
http://m42club.com/forums/showthread.php?t=5462&highlight=cps+testing
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DesktopDave

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How to check cam/crank sensors????
« Reply #4 on: January 12, 2010, 12:35:22 PM »
Quote from: longms;84488
Thanks for all of this information.

Symptoms so far:

No Spark
No fuel that I smell (when I pulled the plugs)
All hoses are brand new but will give them a once over tonight.

Would a bad O2 sensor cause the car not to start at all? If the crank sensor were bad and not sending a signal would that car be able to run? My understanding is that it would not be able to run at all.

I will probe the plugs on the sensors when I get home from work. Do those numbers sounds about right when checking the sensors?

Yeah, sounds like a bad CPS.  Test & report on the resistance.  Your numbers are correct, roughly 600 ohms on the crank & 1200 ohms on the cam sensor IIRC.

You can also isolate the problem by pulling the fuel pump relay & short socket pins 30 & 87 with a bit of 14-16 gauge wire.  Then turn the key on, to position II.  If the fuel pump now runs (it won't turn off BTW) you know it's likely the CPS is bad.
« Last Edit: January 12, 2010, 12:38:13 PM by DesktopDave »
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Sold: '97 Montrealblau 318iS, '91 Brilliantrot 318i, '91 Brilliantrot 318iS

longms

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How to check cam/crank sensors????
« Reply #5 on: January 12, 2010, 01:33:33 PM »
RED IS 91- I know, I know...I do need to get those manuals. They would probably answer a lot of questions that I seem to have.

Thanks for the responses. I will try the short socket method for fuel pump relay and check the resistance on the sensors.

If it turns out to be the cps should I replace bith crank and cam sensors? And, where can one order the crank position sensor? Are the crank and cam sensor basically the same thing? I can't seem to find it on Pelicanparts.com.
\'91 318is Alpine II- | HR Sport/B-Sport | Poly RTAB/Motor Mount/Tranny Mount/Diff Mount | Treehouse FCAB | IE Sways | 19# Injectors | SSR Comps | Hawk Pads | Fog Delete | Magnaflow Exhaust | Z3 SSK |

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How to check cam/crank sensors????
« Reply #6 on: January 12, 2010, 02:34:01 PM »
I didn't find it there either.  Likely you could call.  I did find one here:
http://www.partsgeek.com/catalog/1991/bmw/318is/engine_mechanical/crank_position_sensor.html

I'd replace only what was dead...crank & cam sensor are basically the same style of sensor, with different mounts & likely different sensitivities.
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fiftytakedowns

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How to check cam/crank sensors????
« Reply #7 on: January 12, 2010, 02:51:03 PM »
Quote from: DesktopDave;84492
Yeah, sounds like a bad CPS.  Test & report on the resistance.  Your numbers are correct, roughly 600 ohms on the crank & 1200 ohms on the cam sensor IIRC.

You can also isolate the problem by pulling the fuel pump relay & short socket pins 30 & 87 with a bit of 14-16 gauge wire.  Then turn the key on, to position II.  If the fuel pump now runs (it won't turn off BTW) you know it's likely the CPS is bad.


Sorry for the Hijack:
but Dave, If my car's fuel pump is turning off causing my car to bog due to crank position sensor, or soem other sensor, could I jumper this, and drive it around the block to see if it continues to bog? If it doesnt bog that means that it is getting a signal to turn off the fuel pump? If it does, it must be ignition then? or the Injectors are getting a signal to turn off.

longms

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How to check cam/crank sensors????
« Reply #8 on: January 12, 2010, 02:54:57 PM »
I am not sure if those pictures are representative to what the sensors really look like but those look way different than what the stock ones look like. I can get those or should I get the from Bmrparts.com? $50 gets a used one with a 6 month guarantee on it.

I am getting them overnighted and the bmrparts is charging $35 and the partegeek will charge $25. So they are basically the same price. I am thinking the brand new one is the better call.

Correct me if I am wrong.
\'91 318is Alpine II- | HR Sport/B-Sport | Poly RTAB/Motor Mount/Tranny Mount/Diff Mount | Treehouse FCAB | IE Sways | 19# Injectors | SSR Comps | Hawk Pads | Fog Delete | Magnaflow Exhaust | Z3 SSK |

RED IS 91

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How to check cam/crank sensors????
« Reply #9 on: January 12, 2010, 04:44:29 PM »
Go to http://www.bavauto.com/
enter your car info and type in the search crankshaft position sensor and it will pop up.
They are a great asset .
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How to check cam/crank sensors????
« Reply #10 on: January 12, 2010, 04:50:12 PM »
These are on this site ............

this will get you the manual for your engine I believe..........

http://m42club.com/forums/showthread.php?t=2282

This one for your body..............
http://m42club.com/forums/showthread.php?t=964

The books are a lot better but maybe this will get you in right direction.
Good luck
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longms

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How to check cam/crank sensors????
« Reply #11 on: January 12, 2010, 08:02:08 PM »
just tested the sensors and got 1.195 Kohms (which is 1195 ohms iirc) from cam sensor and tried every possible combination between the 3 prongs on the crank sensor and could not get a reading anywhere.
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DesktopDave

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How to check cam/crank sensors????
« Reply #12 on: January 12, 2010, 08:03:55 PM »
Quote from: fiftytakedowns;84499
Sorry for the Hijack:
but Dave, If my car's fuel pump is turning off causing my car to bog due to crank position sensor, or soem other sensor, could I jumper this, and drive it around the block to see if it continues to bog? If it doesnt bog that means that it is getting a signal to turn off the fuel pump? If it does, it must be ignition then? or the Injectors are getting a signal to turn off.

That's a tough call.  I'd suspect a flaky relay, connector or pump.  Possibly a fuel line leak or FPR too.  IIRC you'd replaced most of those though.  If you shorted the FP relay the pump would run all the time the key is on.  Might be useful for troubleshooting, try it out and let us know how it goes.

I'm an computer geek so I always test, test, test.
« Last Edit: January 12, 2010, 08:27:01 PM by DesktopDave »
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How to check cam/crank sensors????
« Reply #13 on: January 12, 2010, 08:07:45 PM »
Quote from: longms;84511
just tested the sensors and got 1.195 Kohms (which is 1195 ohms iirc) from cam sensor and tried every possible combination between the 3 prongs on the crank sensor and could not get a reading anywhere.

Yeah, Cam PS checks out...but Crank at zero resistance = very bad sensor.  It must be internally shorted & not sending any signal.  Isn't that kind of a dumb system?  I prefer the impact/rollover fuel shutoffs myself, hopefully I'll never have to use one.

I'd recheck the reading if it was me (mine was jumping around a bit & tested low the last time I did this), but it wouldn't surprise me.  Check the dealer price, they might surprise you & be pretty close...  Last time I was there the part (radiator bleed screw) was in stock and reasonable.  I was like :eek:... :cool:.
« Last Edit: January 12, 2010, 08:09:47 PM by DesktopDave »
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Sold: '97 Montrealblau 318iS, '91 Brilliantrot 318i, '91 Brilliantrot 318iS

longms

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How to check cam/crank sensors????
« Reply #14 on: January 12, 2010, 08:23:58 PM »
crank sensor at dealer was like $225:eek:...found one at partsgeek for $60...i believe it is a Delphi brand...is this a good brand?
\'91 318is Alpine II- | HR Sport/B-Sport | Poly RTAB/Motor Mount/Tranny Mount/Diff Mount | Treehouse FCAB | IE Sways | 19# Injectors | SSR Comps | Hawk Pads | Fog Delete | Magnaflow Exhaust | Z3 SSK |