Hello everyone. I am new to the site and I am also a new Porsche owner and picked up a 2005 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 anything like this. Just an FYI, I have worked on German cars (Mercedes and BMW Master Cert) for over 10 years, but I do not sling wrenches full time anymore. With that being said, this is the problem and what I have tested.
The car is very hard. When it starts, I can get the revs to climb, but not very fast. Then when it gets to around 3000 RPMs, the will engine will cut off for about 0.5 seconds and then light back up. It keeps doing this the whole time that it runs, but I have to pedal it to keep it alive. While it is lit, I am getting a MIL light and also the green light for the soft top being open.
When the car does this surge thing, both of those lights cluster lights are lit, but while the car is cutting out, those lights will both turn off and the other lights around the car will dim as well. After the RMPs fall for that half second, the MIL and top light will come back on and the car will come back alive. Also, when the car cuts off, it is very abrupt. Not like it is losing fuel pressure from a fuel pump cutting out, but more like it is shutting down. Also, there is not shutter when it cuts out, it just turns off.
FYI: The previous owner installed a new cam sensor and I think that it was on the driver’s side but am not 100% sure.
So what I have checked and has been done so far is this:
With an OBD2 scanner (Bosch Blue Tooth with cell phone App), I was able to pull 3 codes from the system. All fault codes have been cleared and they will keep coming back.
1. P0335 – Crank Position Sensor A Circuit Range / Performance (Hard Fault)
a. Crank sensor has been swapped and the problem has not changed.
2. P0341 – Cam Position Sensor A Circuit Range / Performance B1
3. P1502 - Throttle Jacking Unit, Spring Test – Above Limit
Other Diag work done:
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. (No Change)
1. I used a Snap-On graphing meter (Vantage) and scoped all of the powers and grounds that are running through the ECU. There were no drops or flux
2. Checked car voltage while it was running and I think I was getting around 13.8v – 14.0v DC and 0.12v - 0.08v AC
3. At the ECU, I checked injector pulse, coil pulse. I found that I am not dropping ignition, but I am dropping injector output.
4. I tried to pull the OBD2 live data, but can only do so when the car is not running. While it is trying to run, the scanner will say that it can’t pull the PID data from the ECU. But when it is not running, all of the data looks to be ok.
5. I also checked for vacuum leaks and was unable to find any that I noticed.
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.
Boxster S
Stang
FunToy
Linear Mode
