I am having a surging issue after getting an EVOM tune on my 2004 cayenne turbo and hoping someone can help. Car has 60k on it and coolant pipes have been replaced. This is what has been installed. EVOM intake, EVOM diverter valves, IPD plenum, leistung bypass pipes and EVOM tune which brings me to almost 600hp. In the process of trying to fix the issue, I have replaced the fuel filter, fixed various EVAP issues prior to the tune, replaced all the spark plugs and coils with newest OEM. My issues with the OEM spark plugs was getting surging almost at any time putting more than 50% throttle. Decided to change out to NGK iridium IX BKR6EIX plugs and narrowed the gap to about .025. Symptoms dramatically improved and now only issues around mid rpm range. Decided to go with a colder plug and used NGK iridium BKR7EIX plugs and get the gap as they came which is about .028 or so and symptoms are slightly better. On the first couple runs after I had put either of the NGK plugs in, no problems at all and it pulled hard. After the car warmed it, is when the surging began. Now it seems pretty consistent around the 3500-5000 range when ever I try to give it 2/3 to full throttle. The first drive with the car before it warms up seems much better and symptoms get worse as car is warmed up. I am not having any issues with idle or normal driving. I don't think it is a fuel system issue because wouldn't I see idle issues or other normal driving issues. Do I need to go even colder with the plugs or should I be looking for something else. On my durametric, no codes come up either throughout this entire process of changing spark plugs.

 

This type of issue can be tricky to pinpoint without a code or taking it to someone with a lot more experience. Did you did for any air leaks after the MAF sensor?

 

Since you have Duametric, I would do some data logging and see what values are being affected. In my case, timing was being pulled dramatically when I would hit boost, lambda values would go VERY rich, and the injection time was going up. MAF values were perfect match left and right at all times. Put in the NGKs in the 6 range, and helped a TON, though have not logged since, that was only a few days ago. Would be a good start to see possibly whats causing the issue or whats being done by the engine to feel it.

 

I have checked for mad leaks and don't have any. I have tried to ngk heat range 6 plugs and it was worst than using the 7 range. I could start logging with the durametric but what values should I log.

 

I logged RPM, Load, Intake air temp, Ignition angle, Actual Lambda value 1 and 2, Injection time, and MAF 1 and 2. In my case, when full boost was to be coming on, my timing was going from 25-28, all the way down to 1 or 2, injection time was going up, and O2 sensors were showing very rich condition.

 

I think that I am getting similar issues. I have attached some durametric readings in a 3th and 4th gear run on the first sheet and a 4th gear run on the second. I am hoping that someone can help me interpret the data and what my problem might be.

 

Almost exactly what mine looked like. I have not done any more since replacing plugs but it feels much better from the seat. One thing that was suggested to me to try was add about half a tank of 100 octane if you can find it to half a tank of 91 (or 93 if youre so lucky). I have not yet done this as I wanted to rule things out step by step.

 

I am wondering if I should have them change the ECU tune to lean it out a bit. Do you think that might help.

 

I would try and figure out why its pulling the timing. Its going rich for a reason, and like mine, be glad its going rich. If you get it too lean and it continues to do what its doing, that's going to create bigger problems.

 

A few dumb questions: has your car been into the dealer lately? Have you contacted EVOMS?

 

I have been to the dealer and all obvious problems have been evaluated. I just sent EVOM a couple runs from my durametric and they think that looks to be a problem that they are going to let me know when they look at it. It seems I am experiencing a rich air/fuel issue.

 

Any updates on this? I am having similar issues and I'm just getting ready to start diagnosing.