how to test my cps , crank position sensor iffy ???

Post Mon May 27, 2019 2:41 pm

Good afternoon all .

I've been chasing a fault for a while now and have changed a lot / checked parts .
issue is when cold blip the accelerator car dies . once its warm usually seems o.k

but one thing I have not checked / changed is the crank position sensor. can this give intermittent issues, as once car died on the road

how do i check this ? and if i need new one , what make type would you recommend , I don't want to buy a cheap chinese one and end up worst of.

thanks any constructive replies appreciated

Post Mon May 27, 2019 2:49 pm

Have you checked this thread?

Help me identify the low idle on cold start issue *Problem Found and Fixed*

lots of info on what to test and a strange outcome too

Don't buy a CPS that's not a reputable oem make - they are wildly different, wrong impedance and so on - I have a new one that simply doesn't work
but tests correctly. Only real way to check is with a scope.

Paul

Post Mon May 27, 2019 10:38 pm

There is a multimeter test you can do, im certain the info is in the wiki. This is the best deal I could find on eBay, not a bad price for a bosch part (Im assuming you have a 325i?)

https://rover.ebay.com/rover/0/0/0?mpre ... 2410293028

Post Mon May 27, 2019 10:56 pm

there's also these from rock auto in the US.

https://www.rockauto.com/en/catalog/bmw ... ensor,7196

i've had a few parts from them without any problems.

Post Tue May 28, 2019 9:13 am

Yup, should read 540 ohms across the sensor, at the the sensor plug and at the ECU - but as the wiki states, a correct resistance reading does not mean the unit is good - it's not
a bad idea to carry a spare anyway, it's small and is one of the things that will stop the car dead if it fails - same as with the DME relay.

Paul

Post Tue May 28, 2019 9:14 am

Paul is right, there are various sensors out, i believe due to the e models which have 800+ ohms resistance.

I replaced mine with a Meyle brand one, two months later car would not start. Turned out the wire got wedged on the water pump pulley and started eating itself.

I got a "new style" one, which comes with a plastic housing from Redix or similar brand. Also same resistance, everything is fine.

Post Tue May 28, 2019 10:24 am

paultv wrote: ↑
Tue May 28, 2019 9:13 am
Yup, should read 540 ohms across the sensor, at the the sensor plug and at the ECU - but as the wiki states, a correct resistance reading does not mean the unit is good - it's not
a bad idea to carry a spare anyway, it's small and is one of the things that will stop the car dead if it fails - same as with the DME relay.

Paul

the resistance should read 540ohms +/-40 ohms either way.

Post Tue May 28, 2019 1:31 pm

Yup, should read 540 ohms across the sensor, at the the sensor plug and at the ECU - but as the wiki states, a correct resistance reading does not mean the unit is good - it's not
a bad idea to carry a spare anyway, it's small and is one of the things that will stop the car dead if it fails - same as with the DME relay.

yes thanks . when you say across the pins there are 3 pins , across which ones.
good idea to carry a spare , at least you can bridge the dme relay , if you know what your doing.