engine cuts out and won't restart

[Palbox]

New to the forum; 2000 Boxster (2.7L engine assembled in 1998; manual transmission, transmission code ends in 002 and is a topic for another day!).

 

Engine recently started cutting out driving home from work. The engine cuts out with no warning (no 'roughing' etc). When it cuts out, it won't restart. Hours later, engine magically starts again and runs like nothing ever happened until cutting out again. The behavior is identical whether idling in my driveway or driving. It doesn't seem to be temperature related.

 

The way the engine cuts out with no additional symptoms or warnings, I doubt it's a fuel pump issue? Could be a clogged fuel filter, but after a while the car starts up again with no apparent issues making me doubt it is a fuel filter issue?

 

Crankshaft position sensor: when cranking my car the tachometer stays at 0 until the engine starts. So does my other car. I see several posts that the tachometer should show a reading as the engine cranks before but before it starts. This is not the case for my two cars. People also post that if it is a CPS problem, then the engine should start again right away? I would expect the fuel supply to be cut off if the CPS doesn't signal to the ECU? Could my problem be a failed CPS even though it doesn't seem to be temperature related?

 

My passenger side door lock is acting up. The car has been giving the characteristic 'double-honk' when locking and unlocking for a while and the window doesn't stay down the tiny bit it's supposed to when the door is open. It was on the list to fix this month. Shortly before the engine started cutting out, the 'double-honk' started sounding while driving and often. Could the problem be alarm/lock related?

 

Shortly before the engine started cutting out, I had a few instances of the key not turning easily in the ignition switch. I read that many weird issues can arise from a faulty ignition switch; I haven't found descriptions of engine stalls though. Could a faulty ignition switch be the problem?

 

I do have a P0442 error code; have had it for a long time though. It comes and goes, and a fuel tank vent replacement is also on my list of upcoming fixes. I doubt that it has relevance to engine problem (?), but full disclosure. No other error codes on my OBDII.

 

Any other suggestions?

 

Lastly, if I wanted a computer that could read/reset everything to help diagnose the problem, what would be options within reasonable budgetary constraints? Any computers that would also work for my other car (Mercedes Benz CLK350)?

 

Thank you for your time!

Edited May 21, 2019 by palbox

[crwarren11]

Having recently gone through a fuel pump replacement and a crankshaft position sensor replacement, I suggest going through the diagnosis process. Check the fuel pressure, check the fuel pump relay, short the relay and confirm the fuel pump is running. As a first timer for a fuel pump replacement, I had no idea what I was listening for but I can tell you that you can hear it whirl without any difficulty when it runs. You can also apply 12v directly to the pump to confirm if the pump is the issue. In my case, the CPS was not the problem, it was the fuel pump, but not having gone through it before all signs seemed to point to CPS. No tach jumps is more indicative of CPS but I would also make sure the fuel pump runs and is providing pressure before assuming it is the CPS. I use durametric and tried several generic obd2 readers with no luck. I’m not aware of any other good options for Porsche’s. 

[irogag]

Are you getting W Lead (Code 49 on the alarm ECU)?

 

If the problem is that intermittent and only can occur in dangerous highway situations....quit driving the car till you can recreate it and safely diagnosis it in the safety of your driveway with a Autel, Duramatic, etc.  If do you something and it just starts back up..

How can you confirm it was your repair or just time related to a magic restart?   Since you can't,  you must fail the part ala Dave and Hal From 2001 Space odyssey .

(PS if you live near Houston I could help you with my Autel scan tool diagnosis all of the systems but beyond that I would buy one if I were you and plug it in and drive it till it happens).   Also you can buy a cheap obd2 elm style bluetooth scan tool for your phone....and with Torque app just read basic info like fuel and ecm related stuff))

Edited May 21, 2019 by irogag

[Palbox]

10 hours ago, crwarren11 said:

Having recently gone through a fuel pump replacement and a crankshaft position sensor replacement, I suggest going through the diagnosis process. Check the fuel pressure, check the fuel pump relay, short the relay and confirm the fuel pump is running. As a first timer for a fuel pump replacement, I had no idea what I was listening for but I can tell you that you can hear it whirl without any difficulty when it runs. You can also apply 12v directly to the pump to confirm if the pump is the issue. In my case, the CPS was not the problem, it was the fuel pump, but not having gone through it before all signs seemed to point to CPS. No tach jumps is more indicative of CPS but I would also make sure the fuel pump runs and is providing pressure before assuming it is the CPS. I use durametric and tried several generic obd2 readers with no luck. I’m not aware of any other good options for Porsche’s. 

The car idles perfectly normally and steadily when I leave it turned on in my driveway. It typically cuts out after 20 min to an hour. Wouldn’t a failing fuel pump give varying fuel pressure and a resulting rough idle?

 

Thank you for your advice; I’ll try and figure out how to run your suggested diagnostics. My boxster is a ‘learn-as-I-go’ project that I usually really enjoy. This time though, the car is parked for good in my garage, so a little less fun!

[Palbox]

3 hours ago, irogag said:

Are you getting W Lead (Code 49 on the alarm ECU)?

 

If the problem is that intermittent and only can occur in dangerous highway situations....quit driving the car till you can recreate it and safely diagnosis it in the safety of your driveway with a Autel, Duramatic, etc.  If do you something and it just starts back up..

How can you confirm it was your repair or just time related to a magic restart?   Since you can't,  you must fail the part ala Dave and Hal From 2001 Space odyssey .

(PS if you live near Houston I could help you with my Autel scan tool diagnosis all of the systems but beyond that I would buy one if I were you and plug it in and drive it till it happens).   Also you can buy a cheap obd2 elm style bluetooth scan tool for your phone....and with Torque app just read basic info like fuel and ecm related stuff))

I currently only have a basic OBDII reader. It doesn't read alarm codes. I am researching getting something more advanced at a reasonable price point. It would be awesome with a device that could cover both my cars (Porsche Boxster and Mercedes Benz CLK350 that has a recent SRS error - just can't catch a break from these cars!). Autel? Any other directions to look?

[boxster_nut]

"My passenger side door lock is acting up. The car has been giving the characteristic 'double-honk' when locking and unlocking for a while and the window doesn't stay down the tiny bit it's supposed to when the door is open. It was on the list to fix this month. Shortly before the engine started cutting out, the 'double-honk' started sounding while driving and often. Could the problem be alarm/lock related? "

 

I am currently going through this process.  I can tell you  what I have learned so far.

The ' lock followed by a double honk followed by the locks unlocking' is a symptom that a door locked sense switch is malfunctioning.  Supposedly a durametric diagnosis would point to the door with a malfunction.  There are 3 (or maybe 4 I don't recall the exact number) additional microswitches in the door lock assembly that sense if the handle if pulled up (tells the window to drop down (5mm?), a lock/unlock sense switch, and...I forget the others at the moment. The 'shotgun' approach to solving the problem is to buy the door lock assembly....$300 from pelican.  Depending on your model year, there are 'Volkswagen equivalent' door lock mechanisms that sell for about $150ish. The trick is finding the part number cross from the Porsche number to the VW number.  There is the used door latch mechanism approach that goes for $50-100 depending on the recycler.  Finally there is the DIY disassembly the door latch and replace all the microswitches yourself approach.  You can find information in all of these on this forum and other Porsche and even Volkswagen and Audi forums.  Be prepared to spend a lot of time googling to get a clearer picture of things.  I have a posting in this forum where a fellow outline the problem and included pictures - search under my user name.

 

Personally, I am going to disassembly my door latch assembly in the next 1-2 weeks and determine the part number of the existing and suitable replacement switches.  There is nothing special about them. They are supplied by Cherry  Switch and Burgess (Johnson switch).  I personally refuse to spend $600 on two door latches when I can rebuild them for no more than $50 worth of parts and 2-4 hrs of my time. 

 

BTW, there is a 'trick' to lock the car with the symptoms you describe.  Close all the doors and manually lock the car and after  you hear the locks energize, turn the key to the lock position 3 times very quickly.  This is emergency procedure to lock the vehicle.  It basically signals the control module to override/ignore the door open switch and keep the locks closed.

You may be able to hit the lock on the key FOB 3 times to have the same effect-it did not work on my 97 boxster.

Good luck

J

 

 

[Palbox]

Update: I measured fuel pressure on the fuel rail. It's odd...

 

When turning the key without starting the engine, the fuel pump builds up a pressure somewhere between 5 and 25ish psi (it's inconsistent). However, when I pull the key out of the ignition switch and put it back in and turn without starting the engine, the pressure builds up to around  40ish. Pressure is stable over long periods of time.

 

When I turn on the car, the pressure does one of two: 1) moves to ~44-46 psi and stays there as the engine revs or idles or 2) moves to 30-35ish. As the engine revs, the pressure can be 'pumped' up to 44-46 psi and stays there even when the engine idles.

 

Fuel regulator looks good; no gas in vacuum line or coming out of regulator. When vacuum line is removed, the pressure jumps - as expected - to 55ish. Pressure lowers to 44-46 when vacuum line is plugged back in.

 

Here's the kicker: when turning the engine off, the pressure INCREASES over time from 44-46 to over 50 psi! Could this be a clogged fuel filter (pressure high on upstream side of filter and low on the rail side; after turning the engine off pressure evens out over time)?

 

Bad fuel pump?

[crwarren11]

Check this post for reference. Some good info  

Fuel System Testing - Rennlist - Porsche Discussion Forums

RENNLIST.COM

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993 Forum - Fuel System Testing - This thread is going to be about testing the fuel system. In Part 1, instructions are given for checking fuel pressure and...

 

[Palbox]

Excellent post! Thanks for the reference!

[cjp69]

@palbox, were you able to fix your problem?  Fuel pump or CPS?  

[Palbox]

@cjp69Yes. Was very simple! The fuel vapor regeneration valve (can be found under the left side intake plenum) was broken and perpetually stuck in "open". So fuel vapor after fueling or immediately after driving would saturate the intake and cylinders and the car wouldn't start! I replaced the valve with the aftermarket Bosch valve (996-110-129-06-M14) since it's about 1/6 of the price for the Porsche part. The aftermarket part comes without lines; I cut the original lines and mounted the new valve with ~$10 hoses and hose clamps from the local auto store. Took 15 min and the car has had no issues since I FINALLY found the culprit about a year+ ago!

Edited February 18, 2023 by Palbox

[Palbox]

So. It. is. happening. again! Argh! After running great for more than a year, Sabine (that's my 2000 Boxster's name) started stalling again when idling. Sounds like she is running rich and then stalls. What I still don't get is that after she stalls, the fuel pressure on the fuel rail is 0 (measured in real time with a fuel gauge)! Sabine has only ever been in a shop once and that was to get a new key. I had sworn I would learn everything I could about cars with Sabine and fix everything myself (I had never fixed anything in my life prior to getting this car around 2014-15!). But this time I give in. It's been multiple years and I am uncomfortable driving her since fuel supply seems to come and go here and there. What if it happened going 55 (we all go 55 on freeways, right?) on the freeway?

 

I am taking her in to Tom Wood Porsche Indy next week. I trust them; they perform all service on my Panam and they are really good! I'll try and post what they come up with! This error has been sooooooooo annoying! And no error codes to work with this time...

Edited May 23, 2023 by Palbox

[crwarren11]

No check engine light or codes? 

[Palbox]

Nothing at all! Figured I'd give an update in case someone else is struggling with similar issues.

[stevetran]

I am having the same problems. I have 02 996 tt. I would let it run idle for about 20-30 minutes and it would stall out. Try to start it and the engine would turn about 1-2 seconds and cut off. after leaving it or a couple of hours it would start up again. I am lost at this point and really don't know what the issue is. These are the parts I have replaced and my fuel pressure is good. Any help would be greatly appreciated!

 

- Battery

- Fuel pump

- Fuel filter

- Cleaned throttle body

- MAF sensor

- ignition switch

- crankshaft positioning sensor

- fuel pump relay 

[stevetran]

On 5/25/2019 at 4:10 PM, Palbox said:

Update: I measured fuel pressure on the fuel rail. It's odd...

 

When turning the key without starting the engine, the fuel pump builds up a pressure somewhere between 5 and 25ish psi (it's inconsistent). However, when I pull the key out of the ignition switch and put it back in and turn without starting the engine, the pressure builds up to around  40ish. Pressure is stable over long periods of time.

 

When I turn on the car, the pressure does one of two: 1) moves to ~44-46 psi and stays there as the engine revs or idles or 2) moves to 30-35ish. As the engine revs, the pressure can be 'pumped' up to 44-46 psi and stays there even when the engine idles.

 

Fuel regulator looks good; no gas in vacuum line or coming out of regulator. When vacuum line is removed, the pressure jumps - as expected - to 55ish. Pressure lowers to 44-46 when vacuum line is plugged back in.

 

Here's the kicker: when turning the engine off, the pressure INCREASES over time from 44-46 to over 50 psi! Could this be a clogged fuel filter (pressure high on upstream side of filter and low on the rail side; after turning the engine off pressure evens out over time)?

 

Bad fuel pump?

Mine does the same with the pressure reading. I replaced the fuel pump and it still does the same readings.

[Palbox]

@stevetran: Definitely look at my post from February 17. I didn't have any issues for maybe more than two years after replacing the fuel vapor regeneration valve.

 

But I am really tired of this. I don't fully trust the car, so I end up sitting in my Panam instead in the nice weather and I have my now re-painted and re-roofed Boxster just parked in the garage. I got a service appointment on June 2nd and they assume it's going to take a few days to figure this one out after I explained everything I have already found and replaced... I'll definitely give a full update; I assume we are not alone with these annoying car problems...