Need Help on Boxster S Odd Running Problem

[Ronin325i]

Hello everyone. I am a new Porsche owner and picked up a 2000 Boxster S (3.2L) that has a very odd running issue that I need some directional help with. I have been looking for others that had the same problem, but have found nothing. Just an FYI, I have worked on German cars for many years, but am not in that line of work anymore and time is hard to come by. With that being said, this is the problem and what I have tested.
The car is very hard to start. Most of the times the only way I can get it started is to hold it WOT. When it starts, it will climb up in RPMs (not very fast) and then when it gets to around 3000 RPMs, the car will engine will cut off for a short time and the dash lights will dim. Also, when the car starts, the RPMs will drop for a second and then the engine will light back up and the RPMs will climb back up. When the engine does start, both the MIL and the green cruise control light are on, but when the engine stalls, both of those lights will go off while all of the other dash lights stay on. While the car is running and surging, it also makes NO power. Not even enough to get up my driveway. When it is running, the motor sounds good and there are no death noises. Also, this may be normal, but the throttle body makes a very high pitch wine when the motor is off. I can hear it change as I press the throttle as well. Side note, there are few other lights on in the cluster like water level, and the top open light while the top is closed and latched.
So what I have checked and has been done so far is this:
The previous owner installed a new cam sensor and I think that it was on the driver’s side but am not 100% sure.
When an OBD2 scanner, I was able to pull 3 codes from the system.
1: P0335 – Crank Position Sensor A Circuit Range / Performance
2: P0341 – Cam Position Sensor A Circuit Range / Performance B1
3: P1502 - Throttle Jacking Unit, Spring Test – Above Limit
I figured that the sensors with circuit range faults could be related to the power surge, but am not sure. I have checked and replaced the DME relay because I thought that the relay may have faulty contacts and the amp load was too much for the relay to handle causing the system to drop out. I also checked all of the power wires leading into the DME, and I never lost power, but don’t remember the exact voltages during the surge. I think I was getting around 13v – 12.8v DC and 0.12v - 0.08v AC while running.
The other thing that’s odd is that when I try and look at the live data, I can view it fine while the car is not running but the key is on. Once it starts, my scanner can never communicate with the DME to get the PIDs loaded.
Also, I don’t know if this matters, but the boot seems like it was dry, but from looking at the carpet, it looks like the top leaked a little because the carpet has that looks like it was wet before look and feel. More so on the pass side, but a little on the drivers.

Thank you anyone for your help and direction on this.

[Dmitry at Pelican Parts]

Hi Ronin - I've attached a tech article directory for the Boxster from our site. Take a look at it, as it's broken down by section. If you have any tech related questions, post a Comment just below one of the articles and someone will get back to you with more detailed info. Best of luck!

Porsche Boxster Technical Articles


-Dmitry

[Ronin325i]

I am bumping this message because I have had this car for a little while now and still can't figure out what the problem is.
I was getting the crank fault as a hard fault and the motor is still throwing the crank and cam shaft faults. I am also getting the P1502 throttle jacking fault code as well.
Any other help on this would be great. I worked on German cars for over 10 years and have never seen anything like this with the surge and check engine light cutting off with the flash.

[mikefocke]

P1502

- Fuel pump relay faulty
- Short circuit to B+
- ECM faulty

P0341

– No power supply.
– Break in wiring.
– Short circuit to B+.
– Short circuit to ground.
– CMP sensor faulty.

P0335
can't help definitively but bet is Crankshaft Position Sensor

[Ronin325i]

Thank you mikefocke for your help. As for your suggestions, this is what I have checked.
I have checked for fuel pressure while the car is cutting out and the speed that it cuts out is not like a fuel delivery issue. When it cuts out, it cuts out fast. Also, I have checked the power and ground to the ECM while the problem is taking place and I never get any drops. I also checked all of the outputs from the ECM while running with my scope and I don’t drop output to ignition coils but I do drop injector output. I was getting some high voltages when checking the crank sensor AC voltage, so I did change it and am getting no change.
You had a good thought on the ECM fault, and that is my biggest fear. I pulled the board out of the ECM case to check for any burnt spots, but I don’t see any part where the magic smoke would have gotten out at. Can you think of any other way of testing the ECM? When I try to check live data while running, I keep getting a disconnected message from scanner. It will only disconnect while the car is trying to run, but when the car is not running but the key is on, I can connect to the ECM with no problem.

[Luccia at Pelican Parts]

Ronin - we have a much larger Boxster community that may be able to help you with your issue on our 986 forum here: 986 Forum - for Porsche Boxster Owners and Others.

[Ronin325i]

Thank you very much Luccia. I will give that a shot.