DIY Crankshaft position sensor project

[ewinn]

So, my 2004 Saab 9-3 aero is having major problems with the already diagnosed crankshaft position sensor. The car runs with the old one in, but it idles rough, and sometimes shuts off WHILE IM DRIVING! It then takes ten to twenty minutes to restart the car. So i go out and buy and new cps, install it and...the car wont start. I put the old one back in and it starts up fine! I assume its the part i bought so i return that one and buy another, install it and bam...the same problem, it wont start but when i put the old one it it fires up in an instant. My question is, why?!!!
Do i need to program it with a special tool? Idk but i need serious help before the car kills me lol.

[Jn2]

you shouldnt have to program it for a new CPS, only time you need to do a crank relearn is when you remove the crank...maybe you got a faulty CPS

[ewinn]

Well i tried two different ones already so i thought i may have eliminated the chance of having purchased a bad cps..should i try purchasing a third one?

[Jn2]

damn is there no warranty on them? i would recommend, if possible, to find another saab driver and see if swapping their CPS will fix your problem, if there CPs works than its a bad sensor yourve been buying, if theirs dont, than the CPs isnt you problem...you check the CPs wires make sure they are ok?

[dzlsabe]

Is it genuine Delco(Bosch) #12789959? These things are just starting to go bad.

['97 Saab SE Turbo]

When you removed the origional CPS, did you get out the old o-ring? If not, did you insert a new o-ring? If you did, you may have 2 o-rings in the CPS hole and it's not getting close enough to the crankshaft to create a spark. Just a guess... Ron

[Jn2]

Originally Posted by '97 Saab SE Turbo

When you removed the origional CPS, did you get out the old o-ring? If not, did you insert a new o-ring? If you did, you may have 2 o-rings in the CPS hole and it's not getting close enough to the crankshaft to create a spark. Just a guess... Ron

our sensor doesnt make a spark, it has a magent inside, we cut one open a few weeks back to look at the innards...the o ring is there to prevent the oil the crank and slinging from leaking out the block...noting else

[ewinn]

man i wish i knew anyone who drove a 2004 saab!!
I read a lot about the o rings and on my first try i checked to make sure that wasnt the problem..so i guess that leaves me one choice!
Ive returned the other two (thank god) and i guess im stuck having to buy and try a third? Unless theres anyone here that lives in san antonio that drives a 2004 saab 9-3

['97 Saab SE Turbo]

Originally Posted by Jn2

our sensor doesnt make a spark, it has a magent inside, we cut one open a few weeks back to look at the innards...the o ring is there to prevent the oil the crank and slinging from leaking out the block...noting else

Yes I know how it works, but if the CPS is too far from the crankshaft (because of too many o-rings), it can't sense the crank and thus no spark. It works very similar to the ABS sensor and reluctors on the wheel hubs... Ron

[dzlsabe]

It could be any SS,SC,CV with a 4 cylinder.

[JMarkert]

Have you tried a different store, or an online seller? (www.eeuroparts.com, www.thesaabsite.com or the like).

http://www.eeuroparts.com/Main/PartD...px?id=12789959

Either the folks you are buying from have a bad batch, OR their inventory system is reliably selling you the wrong part.

[KenCamo]

Sorry to bump this old thread, I was just curious of what wound up happening?

[JHZR2]

+1 what was the outcome?

[spakilla]

lol lol im going through the axact same stuff now tried two replacement car would not start put the old one back on and starts up fine i can now confirm this is the issue im having and im guessing may need genuine parts to fix this problem

[SaabArt]

bump

Just wanted to see what came of this. I am having a similar issue

[SAABalingus]

Originally Posted by ewinn

So, my 2004 Saab 9-3 aero is having major problems with the already diagnosed crankshaft position sensor. The car runs with the old one in, but it idles rough, and sometimes shuts off WHILE IM DRIVING! It then takes ten to twenty minutes to restart the car. So i go out and buy and new cps, install it and...the car wont start. I put the old one back in and it starts up fine! I assume its the part i bought so i return that one and buy another, install it and bam...the same problem, it wont start but when i put the old one it it fires up in an instant. My question is, why?!!!
Do i need to program it with a special tool? Idk but i need serious help before the car kills me lol.

I've read about aftetmarket CPS's not having a strong enough magnet, or kept tightly boxed with others weakening the magnets polaric strength. It's possible they are old stock they are selling you. Get a genuine one if it's in your budget.

[Saaboheme]

Originally Posted by Jn2

our sensor doesnt make a spark, it has a magent inside, we cut one open a few weeks back to look at the innards...the o ring is there to prevent the oil the crank and slinging from leaking out the block...noting else

This is correct. It is essentially a Hall effect sensor just like the old camshaft position sensors in distributors. It has a magnet and a coil of wire. When the ferrous iron/steel of the crankshaft passes in close enough proximity to the magnet it generates a voltage in the coil and that signals the ECU as to where the crankshft is in its rotational cycle. My bet is the original OP did not get the old oil seal out with the original sensor, as has already been surmised, and is either too embarassed to report back or just has not come across this old post yet. This is a very simple electromagnetic device that rarely fails for purely electricl reasons. Most often is heat and oil based deterioration of the union where the cable enters the body of the sensor allowing H2O in causing an intermittent, at first, short that becomes a permanent one within a short time.