Random stall that cranks but wont start for a random period of time.

[yeeha68]

I have had a good run with my 986 and no problems for a good while, but nothing lasts forever...

In the last month the car will randomly stall and refuse to start back up for an undefined period of time.  When it happens all the lights on the dash will flash on as if the key has just been turned to the on position.  The starter will crank the engine happily but there is no ignition happening.  This will last for an unknown amount of time (20 min or a day) and then the car will start right up again.  Only to stall out later at some unknown point. (15 min or 1 hour).  I have hooked the durametric up to it each time and got nothing, except the last time.  P1571 fault 39, pointing to the immobilizer.  After searching I came upon this thread from 2009, that describes exactly what I am experiencing, but a solution was never posted.

http://www.renntech.org/forums/topic/28462-cranks-but-wont-start-help-please/

 

So to get down to point, I have a few trouble shooting questions and steps I will take next;

 

1.) The ignition switch has been giving me the traditional issues and it probably needs to be replaced (again).  If the electronics in the plastic switch are going bad, could they cause this?  Engine stall, clean crank with no start-up?

 

2.) could the P1571 be attributed to a freak accident during the stall that confused the car since I never got this error before?  After I cleared it and cranked it with no start, there were no new fault codes.

 

3.) Im reading conflicting info on crank position sensors.  Will they relay a fault code, or not?

 

4.) I have tried both keys, ruling out a bad key transmitter.

5.)  I will check the immobilizer under the seat, but don't expect any water damage. 

6.) I will check all the relays.

 

Sorry for the long winded explanation.  If anyone has a history with this, or any insight to #1,#2, or #3, please share.

[JFP in PA]

I have had a good run with my 986 and no problems for a good while, but nothing lasts forever...

In the last month the car will randomly stall and refuse to start back up for an undefined period of time.  When it happens all the lights on the dash will flash on as if the key has just been turned to the on position.  The starter will crank the engine happily but there is no ignition happening.  This will last for an unknown amount of time (20 min or a day) and then the car will start right up again.  Only to stall out later at some unknown point. (15 min or 1 hour).  I have hooked the durametric up to it each time and got nothing, except the last time.  P1571 fault 39, pointing to the immobilizer.  After searching I came upon this thread from 2009, that describes exactly what I am experiencing, but a solution was never posted.

http://www.renntech.org/forums/topic/28462-cranks-but-wont-start-help-please/

 

So to get down to point, I have a few trouble shooting questions and steps I will take next;

 

1.) The ignition switch has been giving me the traditional issues and it probably needs to be replaced (again).  If the electronics in the plastic switch are going bad, could they cause this?  Engine stall, clean crank with no start-up?

 

2.) could the P1571 be attributed to a freak accident during the stall that confused the car since I never got this error before?  After I cleared it and cranked it with no start, there were no new fault codes.

 

3.) Im reading conflicting info on crank position sensors.  Will they relay a fault code, or not?

 

4.) I have tried both keys, ruling out a bad key transmitter.

5.)  I will check the immobilizer under the seat, but don't expect any water damage. 

6.) I will check all the relays.

 

Sorry for the long winded explanation.  If anyone has a history with this, or any insight to #1,#2, or #3, please share.

1) Yes, definitely.

2) Never heard of it doing that, but if the code is not returning, I would not be concerned.

3) No, a failing CPS will often not code when they are bad.  When the sensor fails, the DME simply fails to see the engine turning over, and shuts down the fuel and ignition systems, thinking that the engine has stopped.  They are also famous for being fine when cold, then acting up when they get warm as well.

[flyingpenguin]

Concur with JFP. Although I am not a fan of throwing parts at a problem, based on the info provided I would say it is most likely the CPS. The generic part is Bosch 0261210335 and can be had online or at your FOPS for a little over $100.

 

Changing it out is not a major task; with the rear on jack stands and the right rear wheel off, you will need a hex socket (5mm) with a nice long extension (2 feet is good) to undo its bolt.

 

See also: http://forums.pelicanparts.com/boxster-cayman-forum/593099-my99-boxster-crank-position-sensor-diy.html

 

You do not need to remove the tranny, but the pic in this post shows location very well.

[yeeha68]

Thanks for input guys.  Since I already have a spare ignition switch (I buy them in bulk) Ill replace that first. On that topic, I have the original steering lock assembly, not the new updated one.  Is there anything to that assembly other then moving parts? There are no electronics involved with that assembly right?  That can be replaced with the new model and still use the existing key tumbler and transmitter?  

 

I ask because many many many years ago when I first experienced the cheap ignition switch issue a Porsche dealer told me that if I changed out to the new style assembly the car would be immobilized and it would need to be reprogrammed by them.  I don't see how that's a possibility, but  I quickly learned about the switch only swap myself and have replaced it several times over the years, but maybe its time to start that project.

[JFP in PA]

Thanks for input guys.  Since I already have a spare ignition switch (I buy them in bulk) Ill replace that first. On that topic, I have the original steering lock assembly, not the new updated one.  Is there anything to that assembly other then moving parts? There are no electronics involved with that assembly right?  That can be replaced with the new model and still use the existing key tumbler and transmitter?  

 

I ask because many many many years ago when I first experienced the cheap ignition switch issue a Porsche dealer told me that if I changed out to the new style assembly the car would be immobilized and it would need to be reprogrammed by them.  I don't see how that's a possibility, but  I quickly learned about the switch only swap myself and have replaced it several times over the years, but maybe its time to start that project.

 

You will only be changing out the electrical section of the ignition, so no reprograming is required, just a very small screw driver.

[yeeha68]

Thank you all for the previous input.

I have replaced the ignition switch, checked the relays, and opened up the immobilizer (super clean, and dry) under the seat and I am still experiencing the stall problem, but no faults in the durametric software

 

So now I need some clarification on the next step. 

1. Earlier I asked about the crank position sensor (CKS) with some good reply's about the (CPS) cam position sensor, so I need to clarify the vocabulary.  (@flyingpenguins - your picture points to the CKS but you refer to the CPS)

 

2. I know there are two CPSs and one CKS.  Should I be focusing on the two CPSs, the one CKS, or both?  Will they both (CPS and CKS) cause the DME to not see the engine turning over? 

[JFP in PA]

Thank you all for the previous input.

I have replaced the ignition switch, checked the relays, and opened up the immobilizer (super clean, and dry) under the seat and I am still experiencing the stall problem, but no faults in the durametric software

 

So now I need some clarification on the next step. 

1. Earlier I asked about the crank position sensor (CKS) with some good reply's about the (CPS) cam position sensor, so I need to clarify the vocabulary.  (@flyingpenguins - your picture points to the CKS but you refer to the CPS)

 

2. I know there are two CPSs and one CKS.  Should I be focusing on the two CPSs, the one CKS, or both?  Will they both (CPS and CKS) cause the DME to not see the engine turning over? 

 

Only the crank position sensor will prevent the engine from running.

[flyingpenguin]

CPS in my vocabulary stands for crank position sensor. Sorry for the confusion and late reply. Any luck?

[Schnell Gelb]

If after all this brilliant technical help ,it still will not start -here is a very simple ,no tools test:

Feel under the seats for wetness. If the cabin carpets are wet ,the electronics(under the seat) may be soaked.

There are mods to prevent this and fixes to suggest if the carpets are wet at the lowest part of the floor in the big dimple under the seat.

[yeeha68]

@flyingpenguin and JFP.

Thanks for the clarification on the sensor.  I finally got some time to look at it tonight and removed the Crank position sensor. Removal was pretty straight forward, only took a few minutes and with the sensor disconnected the car turns over without starting just as anticipated.  Once reconnected, it starts right up.  Unlike the ignition switch and immobilizer, which when disconnected will not turn the engine over all.  Period.

So this now leads me to believe the crank position sensor is indeed failing when hot.

Ill keep this thread alive until I solve it.

-k

[Montesinnos]

I think I have a similar problem. Well, I've been having it for 2 months. I wrote a log for it and record a video for the issue. Is it similar?

 

 

Details: http://986forum.com/forums/general-discussions/57599-boxster-wont-start-my-wife-will-leave-me.html

[JFP in PA]

I think I have a similar problem. Well, I've been having it for 2 months. I wrote a log for it and record a video for the issue. Is it similar?

 

 

Details: http://986forum.com/forums/general-discussions/57599-boxster-wont-start-my-wife-will-leave-me.html

 

Welcome to RennTech :welcome:

 

The crank position sensors in these cars are famous for causing warm or hot start issues without throwing any codes.  I'd would definitely take a look at yours.

[Montesinnos]

 

I think I have a similar problem. Well, I've been having it for 2 months. I wrote a log for it and record a video for the issue. Is it similar?

 

 

Details: http://986forum.com/forums/general-discussions/57599-boxster-wont-start-my-wife-will-leave-me.html

 

Welcome to RennTech :welcome:

 

The crank position sensors in these cars are famous for causing warm or hot start issues without throwing any codes.  I'd would definitely take a look at yours.

 

 

 

Thanks for the warm welcome. CPS would be my next check, but my car magically started working yesterday. I will beat on it tomorrow to see if we're good to go. 

The point on my message is to figure out if the OP is having similar problem so I can maybe help him track it down.

[JayUSA123]

There is a test you can perform on the CKP sensor with a multimeter. If you haven't done it yet, I'd recommend it. My 99 Boxster had similar no-start symptoms (although no stalling) and no codes. It turned out to be an intermittently failing crankshaft position sensor; however, even though the sensor was only failing intermittently, I was able to get out-of-spec readings on a multimeter very reliably.

 

1. Remove connector.

2. Connect ohmmeter to CKP sensor connector, pins 1 and 2. Should read 0.8 - 1.0 kOhms at 68 degrees F.

3 .Connect ohmmeter to pins 1 and 3. Should have no continuity (Infinity Ohms.)

 

The continuity test was where I saw an invalid reading on mine. The meter would alternate between no continuity and a high resistance reading. I popped a new one in and haven't had any issues with starting since (car runs better too.)

 

Good luck!

Jay

[Loren]

Have you checked your fuel pressure?

[yeeha68]

Well I think I have solved the issue.  It looks like it was indeed the Crank Position Sensor (CKP).  And in reply to JayUSA123-You are correct on your Ohm readings.  My old one read 10k on pins 1 and 2, while the new one read .9k which is right in range with your readings.

 

And now a word of caution to everyone attempting this replacement.  Removing and replacing the sensor is not a big deal.  It took 10 min. to get the sensor out, and it should take less to get the new one back in.  However, you are working a good distance away from the sensor and using a long extension on a socket to remove/replace a single screw.  Heres the fun part...as I was negotiating the screw into the hole it dropped and disappeared.  After a few minuets of searching I realized that just to the left of the sensor there is an open inspection port for the flywheel.  You cant see it, but you can fit three fingers into it.  Its a half circle shape about the size of a starter hole.  Anyway, the screw easily disappeared into it and was unreachable.  Im embarrassed to even admit this, but I hope this knowledge will help someone else in the future avoid this trap.  

 

After reviewing old pictures from a previous build, I assumed the screw fell into a small pocket cell and was safe from doing damage to the transmission.  That feeling lasted for about a week until I came to terms with the fear of a lose screw in the clutch.  The last thing you need is a screw catching on the flywheel and jamming at high speed.  So for my own peace of mind, I decided to drop the transmission and retrieve the screw.  For those of you who have done this, you know just how fun that was.  Oh well, it only took a day to do and gave me a chance to get a real good inspection in order.

 

As it turned out the screw was indeed in a small pocket cell (see photo attached) and probably would not have caused a problem, but in the end, Im glad that I took the time to retrieve it and avoid future damage.

 

So long story short...Dont Drop the Screw into the Inspection Port!  :oops:

Edited September 21, 2015 by yeeha68

[JayUSA123]

Oh man. Sorry to hear about that lost screw. What a PITA.

Sounds like you solved the problem though. It's so great when intermittent issues are solved!

Enjoy your more reliable car!

Jay

Edited September 21, 2015 by JayUSA123