E36 OBD1 Cam Position sensor ohms?

[dunebuggyjay]

Hi Guys, can these things be checked with an ohm meter? My car runs like crap. trying to figure it out. Replaced alot of the other sensors. Tried to check out the cam pos sensor last night.

I remember reading somewhere it should be about the same as the crank position sensor in ohms. Is there any truth to that? I know there are 2 differnt styles. Im not sure if that depends on what type you have. mine is OBD1. female 3 prong plug.

I just don't want to replace the $110 sensor if its not bad.

I definitely don't see the same ohm reading as the crank sensor though.

Can anyone shed some light on this?

Thanks
Jay

[rajicase]

I remember trying to find this info a while back.. its not in the bentley nor anywhere else.. But my working cmps is nowhere near the cps in terms of resistance, so don't go by that..

What are your symptoms?

[dunebuggyjay]

Thanks for the reply,

Just a total lack of power. Engine doesn't seem as smooth as it should...but I have solid mounts, and light weight flywheel....so who knows. really bad gas mileage. Runs pretty rich.

When i was trouble shooting pretty much everything with the bentley manual, that was one thing it did not have any test info on. I think I was getting something like 15 milliohms or something small like that. I'll probably pull it out, reconnect it and see if placing a wrench near it changes the output voltage.

My coils ohm good, but I know that doesnt really say much. Have an adjustable spark tester I will probably try on them. see if i cant figure this out.

Engine is an s52 converted to OBD1...in an e30. To make matters worse, i also put a turbo on it. when I did the swap. LOL. Now chasing my tail to figure out why it runs like crap. Should have waited on turbo till I got it running 100%.


Engine sat for a LONG time on long island. things were pretty corroded. It only has 29k miles on it. Finding a lot of sensors that no longer work. (crank sensor, knock sensors, etc.)

[dworthy]

IIRC the crank and cam are suppose to be the same 540 +/- 10%.

[dunebuggyjay]

IIRC the crank and cam are suppose to be the same 540 +/- 10%.

Yea, thats what i remember reading. Just checking if anyone actually found that statement to be true on their own car.

Thanks for the help guys.
Jay

[dworthy]

That is the values I use when I test these cars. So go with it, and if you are outside, replace the sensor.

[carwiz008]

camshaft sensor is hall-effect and cannot be tested with resistance.

[dunebuggyjay]

camshaft sensor is hall-effect and cannot be tested with resistance.

Isnt the crank sensor the same type of sensor? The obd1 one in the front of the engine. They look like the same type of sensor.

And I know that that one can be checked with ohms. (only because thats how I found out it was bad..when my car wouldn't start)

Not arguing, just asking.

Last night I took my camshaft sensor out last night. I find it open on all pins now...so I am pretty sure its junk. Cant get any ohm reading at all now.

Also found my vanos solenoid to not be working too. By putting 12 volts to it. It didnt move the first few times I tried. Then it did...then it shorted it self out. LOL. WTF.

At least I am slowly narrowing it down why my car runs like crap. Just wish I was made of money.

Jay

[rajicase]

There is nothing that says the cmps is supposed to be +/- 540 ohms. That is for the cps.

Sounds like you ruined your vanos solenoid.

[dworthy]

There is nothing that says the cmps is supposed to be +/- 540 ohms. That is for the cps.

Sounds like you ruined your vanos solenoid.

Correct, even the Bentley manual doesn't say anything about this sensor. So when I bought a new one, it was the same as the crank position sensor, so that is why I say they are both the same resistance.

[carwiz008]

They are both hall effect for obd2. Crank is VR type for obd1.

When powered, a hall sensor will either show 0V of 12V depending on whether or not there is a piece of steel in front of it. Independent of RPM but needs 12V power to operate.

VR sensor produces current (and voltage) each time a tooth passes the sensor. Does not require power but must be spinning to operate.

[boarder2k7]

Also found my vanos solenoid to not be working too. By putting 12 volts to it. It didnt move the first few times I tried. Then it did...then it shorted it self out. LOL. WTF.

What do you mean by "it shorted itself out?" What makes you think it did?

[dunebuggyjay]

What do you mean by "it shorted itself out?" What makes you think it did?

The piston was stuck. It finally came loose, then it shorted it self out. I was VERY careful with polarity. It's pretty well labeled. It's an internal short.

[DSGBUILT]

We’re Are you able to get a resistance reading from a new camshaft sensor?

[spyderg0d]

If theres a change in reading when you pass metel over it, it works. It will change in resistance if the object isnt speeding by fast enough I beleive. The dme only needs a change of .03 ohms to be able to read I beleive as when the engine is running, it sees much less than that at high rev.

[ed323i]

I discovered something very interesting today: At least the M52 MS41 DME can run with only one position sensor connected. So it can run with ONLY the crankshaft sensor, or with ONLY the camshaft sensor. And, it runs better with a bad sensor disconnected than with the failing sensor connected. I'm 95% sure this also applies to the Motronics 3.1 M50 DME.

Here are all the details: #50

We can now safely apply this rule to the crank/camshaft position sensors:
Disconnect one sensor -> does it run fine -> you know for sure that the other sensor is 100% fine.
Does it stop running or does it run very badly -> you know that the other sensor is bad.

So, in your case, just disconnect the crankshaft sensor, and IF your camshaft sensor is fine, it will run with only the camshaft sensor connected. If it's not good then it won't run (or very poorly).
Second test: Reconnect crankshaft sensor and disconnect the camshaft sensor. If the engine runs better than before, then the camshaft sensor is probably bad. In which case, only buy the original Siemens part.. In the details-link above it's explained why..

W.r.t. testing: Bentley shows a (I think incorrect) Ohm-reading for the crankshaft sensor, but has no diagnostics what so ever for the camshaft sensor. I think I read somewhere it will only show 10-20 Ohm, but not sure. Best way to test is to connect an oscilloscope to the sensor and then crank the engine. But above testing procedure (disconnecting the sensors and checking how engine runs) is probably the one way to be 100% sure a sensor is good or not.

[spyderg0d]

Almost. In 413 dme (obd1) the crank sensor is for spark timing amd fuel delivery sensing. In other words the engine will not get spark or fuel pressure if the crank sensor is not plugged in. The cam sensor is purely for camshaft position sensing. Its very different in obd2 cars as the limp mode can use either the cam or crank sensor as the basis of engine spark timing in those cars.
The camshaft sensor wave is square, not wave. These are known info you can find in the tuner section or in basic sensor explanations elsewhere.
Its a magnetic sensor. As long as the leads are good and it records a change when placed close to metel the dme can adjust itself to read the output of the sensor all on its own. Most new age second hand sensors will actually be lower voltage drawing sensors that have internal workings to make a readable signal by the dme, not unlike the second hand auto store 1200 ohm cheap crank sensors people buy , or the non magnetic camshaft sensors that dont test empowered but still manage to keep the cell off and run the car.