I have a 2004 cayenne turbo with evom tune, newest revision coils, spark plugs, fuel pumps and filters which acts strangly when warmed up. When car is cold, it drives great and pulls hard under WOT. Once engine is warmed up, the car drives fine under mild and moderate acceleration but under WOT, my aftermarket boost gauge reports that pressure build up to expected 14-16 psi range but the vehicle either starts shuddering under boost and feels like there is no power when accelerating. On rare occasion it goes into limp mode but after about a minute is fine. I have checked durametric multiple times and there are no codes. My suspicion is something electric is going on when the car heats up. Solenoids maybe?

 

How long have these symptoms been present?

 

I have been dealing with this for about as long as I have had the tune. I feel like I have checked everything from spark plugs, coils, fuel system, replaced maf's and the n75 and n249 solenoid. Could my evom air intake be throwing off the readings at the MAF. Could I be developing a boost leak when engine warms up. The problem seems more consistent once vehicle is at operating temperatures. I have durametric and could log some values

 

How many miles on the engine and how long have you had the tune?

 

Engine has 75000 miles and have had the tune since 2011

 

Sounds almost like what my 05 CS is doing.. when engine warm will shudder and pulse almost stall during start of acceleration or while driving.. but no codes at all be sure to report back if u find solution i will too

 

Does anyone have any thoughts on if faulty turbo wastegates or MAF signals being thrown off by heat could throw it off. I have had multiple discussions with EVOM who do not feel as if it is a software issue and that the software should adapt to gas used, installed upgrades, etc.

 

What grade of fuel are you using?

 

I use 93 octane. I am wondering if I am getting turbulent flow at the maf from my evom intake or maybe I have a small intake leak that presents itself when the car heats up

 

I don't think it is the intake. The most difficult part of solving an issue like this is the lack of codes. Without having some sort of direction by a CEL it is hard to determine what is going on. Typically an intake leak will show up as some sort of CEL.

 

I have the intake system oriented with the maf plugs pointed towards the engine like your instructions. I brought up turbulent flow in wondering if I should rotate the maf. Also are any parameters on durametric that I can record to narrow it down.

 

We have sold hundreds of the intake systems and have not hear od this. Maybe just to test, install the OEM air boxes and see if the problem goes away. Unfortunately, I don't think that the durametric log will tell us anything more than just swapping out the OEM airbox.

 

One thing I will add is that every time that I either disconnect the battery or reset the throttle body in durametric, the car runs great for a short period of time which makes me think that the car may overtime trying to correct for some air/fuel imbalance which leads to the driving problems under WOT.

 

The symptoms of shuddering and loss of power under acceleration sound like the symptoms I had on my 04 CS, which where solved by replacing the primary Oxygen sensors.
Also had no fault codes. I had suspected and replaced MAF sensors first with no success.

 

That is a good thought, but I had replaced my O2 sensors, not with geniune porsch sensors but the OES bosch sensor which technically should be the same, just without the porsche stamp. Maybe when the sensor warms up, it is throwing bad readings which could be a possible cause for my symptoms. Is there something in durametric I can look at to see if the O2 sensors and reading funny.