Hello All,
Been around here for a bit though not often as this vehicle has been one of the most trouble free I have ever owned. 2009 Cayenne S, 105,000 miles. Never a major problem since I've owned it, couple of early issues dealer took care of. I have now reached a point where the thing has reached boat anchor status. Let me explain, lengthy.
Back in June 2016 I had an error code from the thermostat not closing and the engine not heating fast enough for the smog stuff to work. Surmised using my Durametric and then proceeded to replace the thermostat and while I was in there the water pump as well. After that was done about a week later I had the dreaded high pressure fuel pump go slowly out until it wouldn't run. Useful forum here with the step by step replacement guide, replaced pump, everything great except now I'm getting a 1025 code on the durametric, which doesn't have a description. Talked to Durametric, great bunch if you ever need to deal with them, and sent some data files to them and they responded that it appeared to be the High Pressure Fuel Adaptation Value #1 and it was too low. When I looked at it on the Durametric it reads a steady 0.69, below the normal range of 0.72-1.50. This one throws the check engine light and I need an inspection of the car (Houston, smog) and it won't pass. So after much investigation into this part of the operation of the engine I finally gave up and went to an indy (40 years Porsche experience, pretty much all he does) and he of course has the PIWIS and reads out the problems, and after getting the immobilizer codes and what not from Porsche reprograms the DME to see if that will fix the Adaptation problem and the value is now dynamic and is within the range. Fixes it for about 20 minutes of run time, CEL comes back on and the value has again dropped to 0.69 and static. Went out into the mechanic only forums and asked questions to whomever would listen and got nothing back. So now we are into late December and still no resolution but still working on it, new high pressure fuel sensor, initially did a complete fuel delivery test, passed, smoke tested the vacuum system, passed. High Pressure Fuel set point and actual values were tracking like they should but Adaptation is still stuck at 0,69. Then when the new year rolled over Porsche NA has now decided to take all the Cayenne programming ability (and files) away from indys so overnight the file for my car is gone off PIWIS. Hmmm, now what: the dreaded dealership is the only option. There are a few here in a big city and the indy knows that the guys at one dealership are more experienced (i.e. old) than the others so I take it to them on Feb 2 and the service writer assures me they will fix it. So 5 weeks later after the only interaction I had with him was when I drove the 25 miles to the dealership to see him in person (no returned voicemails, no messages returned) 3 times but hey if he can fix it it will all be worth it, right? At one point he thinks it is the gas because it "smells bad" so I let it go another week. I show up yesterday and he says "Good News, it's fixed!) and goes and gets the car says it's running great but as I get into it I see the CEL is still on. He says "Oh, forgot to reset that" Gets the diagnostic computer hooks it up and while he's clearing the code shows me the Fuel Trim Adaptation Values and says "see they're close to one another (Bank1 and 2) so we're all good. I'm thinking to myself....well you can imagine. So I get in and am going to drive back home, pick up the wife and go back to get her car that I had to leave at the dealer. Needless to say on the return trip to the dealer, guess what happens. CEL light comes on. Service Dept closed while I was on the way back so that wasn't an option and frankly I don't think they did a single thing to the car. At least it was no charge or I would have been fighting mad. So I get the Durametric back out today and notice that the HP Fuel setpoint is fine at 40.0k like it should be at idle but the Actual value is jumping all over the place - above and below the setpoint. Hmmm what the.... I looked at it closer and after revving it a few times it seems to be going up and down in a rhythm (which would explain the surging idle) with high points above setpoint and lows way down below the 10.0k point
So in summary does anyone, anywhere have any idea or have seen anything like this. I am trying to avoid the chasing it with parts much like the indy didn't want to start either. I'm going to have a conversation with the Service Manager at another (closer) dealership here that a friend knows this week and see if he has a clue and a course of action. Otherwise I'll have to put a chain on it and drag it down to the water.