jimbomgee

Hi all,

I have a 2008 Cayenne S, 4.8, V8. 125,000 miles

The check engine light lit up today. I used my Durametric and found two error codes...

1027 : Fuel High Pressure Fluctuates
2181 : Cooling System Performance

From what I have read today, the former is perhaps the culprit for the check engine notice, whereas the latter would result in the 'Service Now' message rather than check engine. I did have Service Now displaying already but my Porsche repair guy told me it indicates periodic maintenance is due, such as 60\90\120, and that it could only be cleared by Porsche dealer. Having looked into that more today, I'm not certain he is correct but given all these things, I am choosing to resolve the fuel code first. I suspect the HPFP might be bad so I monitored actual values with the Durametric. Noting that fuel pressure setpoint is 40bar, there are significant pressure deviations above and below; from what I observed it was ranging about 37 - 41 bar approximately. Before I buy a new HPFP and perform replacement, can any of you folks tell me what the threshold from setpoint is to trip the code? Are my observed actual value ranges normal or problematic? See screenshots.

Thanks in advance.

deilenberger

Puzzling - the value Durametic reports is the values in the ECU, and I can't imagine an error being triggered for a pressure of 39.6 bar when the desired pressure is 40 bar. It never went more than 1 bar different from the setpoint.

The two differing faults (cooling system and fuel system) to me - point at something like a bad battery (what is the startup voltage before cranking?) or a communications error. If it was me - I'd reset the codes (since you've documented them) and watch to see if they reoccur. And your Porsche repair guy is blowing smoke.. there are lots of tools that can reset a service reminder (I think your Durametric is capable of that.)

jimbomgee

Thanks.
Anyone know what actual value ranges will trigger the code?

newtowny

2008 CTT with 105k miles. I am having the HPFP symptoms with long crank time and no power at upper revs. My Durametric reading while running at idle show 0 mbar for the Set point and 5400+/- mbar for Actual. Before I go for the HPFP, I'm wondering if this could be a sensor but why would I not have a set point? Isn't that programmed into the module? Error codes are:
0346 - Camshaft position sensor "A" circuit range/performance bank 2
1025 - Fuel high pressure adaption
1026 - Fuel high pressure implausible
0171 - System too lean bank 1
0174 - System too lean bank 2

Using the Durametric is new to me so please go easy. I appreciate any wisdom you have to share.
Thank you!

newtowny

I replaced the (expensive) fuel pump and that was not the problem...any help would be appreciated. Fuel pressure sensor perhaps?

EMC2

@newtowny Assuming you are referencing HP Setpoint - these values you are seeing are not normal:
With the car idling, the HP SetPoint should be in the region of 40 Bar, and the actual values need to track the setpoint as closely as possible. 5400mbar is more like the rest pressure when the vehicle is off.

"1026 - Fuel high pressure implausible" typically points to a sensor problem (but not always)

Porsche advises to fully diagnose the LP fuel system before jumping to HP. As you also have lean codes you cannot rule out a vacuum leak either. I know this from personal and very recent experience
Try and pull some values like the ones in the thread below for comparison.
https://rennlist.com/forums/cayenne-...etric-log.html

TRINITONY

Where did you get your HPFP from?