Help: Power delivery issues on Cayenne S but no CEL

[RX_EVOLV]

Hi guys. Could use some help on an issue having on our 2013 Cayenne S.

During acceleration, when it gets to ~2000 rpms, regardless of gear, the car struggles to deliver powers. The car stutters like I'm driving over a rumble strip under acceleration, and I can see it struggle to build rev. Not too bad when it's cold out or when the car is just warming up, but once it's hot out (like recently) or car is all warmed up, the problem becomes very noticeable. Even the passengers can feel it. So this problem is temperature dependent. My mileage also gone to shit (average >17L/100km). Otherwise it idles fine, no rev bouncing.

The problem is the engine isn't throwing a code, so the shops have no idea how to diagnose. So far I've tried replacing all the plugs and coils, cycling through couple bottles of fuel injector cleaners, and new oil filters. No luck.

Any guesses what it could be?

or any recommendations on a Porsche specialist shop that I should go visit.

[gpomp]

I've had good experiences at both Alpine and Riegel

[SJW]

Coil pack on the outs? Happened to my boat before. Worked great cold then shit the bed when warm. I know motorcycle coils fail the same way.

[flipstah]

Do you have VAGCOM? When I had fuel issues, it wasn't throwing a CEL but showed up in VAGCOM.

Kinda odd that it's not throwing diagnostic codes though. Have you had it inspected for carbon buildup? Mine perked up right after.

Otherwise follow what @gpomp recommended for shops.

[Twin_Cam_Turbo]

Major exhaust restriction?

[SJW]

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Major exhaust restriction?

Banana in the tailpipe would do it.

[RX_EVOLV]

Thanks guy. Will reach out to Alpine.

[ercchry]

Do these have a MAF sensor? Might be worth giving it a clean, also check the fluid level in your transmission?

[RX_EVOLV]

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Do these have a MAF sensor? Might be worth giving it a clean, also check the fluid level in your transmission?

It doesn't have a MAF Sensor. Haven't checked the transmission fluid yet. Unfortunately dont have the tools to do that myself on the Cayenne.

[RX_EVOLV]

Just booked Alphine.. they are booking over a month out. Busy shop!

[03ozwhip]

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Just booked Alphine.. they are booking over a month out. Busy shop!

Did you replace the X5 with this?

[bjstare]

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Just booked Alphine.. they are booking over a month out. Busy shop!

Yeah that's pretty standard, every time I've taken something there it's been 4-6 weeks.

[RX_EVOLV]

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Did you replace the X5 with this?

We had both for a while, but when both wife and I transitioned to WFH full time we were putting less than 10km a year between all 3 cars, so we sold the X5 and kept the one with the V8.

[03ozwhip]

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We had both for a while, but when both wife and I transitioned to WFH full time we were putting less than 10km a year between all 3 cars, so we sold the X5 and kept the one with the V8.

Oh thats alright! I missed mine so much, I bought an '18 last year lol

[RX_EVOLV]

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Oh thats alright! I missed mine so much, I bought an '18 last year lol

I should've just sold it back to you!

Yeh we miss that car alot too. Came really close to pulling the trigger on a G05 X5 last year, but with 2 kids we feel like we should get a bigger car instead. Wife and I have weekly debates on whether we should get a new Sienna or a used X7. Sadly it's looking like it'll be the Sienna...

[Flexray]

This is how I would diagnose this problem.
I would clock onto the job, most of the time I would have one hour of diagnostic time, so the clock is ticking. Grab the scan tool and keys. I'm going to perform a full vehicle trouble code scan, I want to see how all of the vehicle systems are functioning. Let's assume no relevant codes have been set.

From your description, the engine is misfiring or running poorly under load. On the scan tool, am going to graph both mass air flow sensors flow rate values, calculated engine load, air intake temp, engine coolant temp, all fuel adaptation values, misfire or cylinder contribution values. I'm going to go for what is called a flat rate test drive. I'm going to find a open stretch of road, accelerate slowly, cruise for a bit, then wide open throttle until it hits the rev limiter, then hit pause on the scan tool and pull over to review the data.

Under wide open throttle, the calculated engine load should be around 90% and the fuel adaptations should be +-10%. If the engine load is below 90% the engine has a breathing problem or an air flow calculation problem. With both of these I have seen fuel adaptations go positive or negative. 92A's have two hot film mass air flow sensors right after each engine air filter. The hot film gets dirt baked onto it causing the sensors to under report, and usually causes positive fuel adaptations. If this is the case, come back to the shop and clean the air flow sensors and see what the data does and if the engine runs better. Only clean the sensors with mass air flow sensor cleaner and a q-tip. Cleaning sometimes fixes the problem, other times it will get better but not fix it and you have to replace the sensors.

At this point, you only have a few minutes left before you run out of time. For the next test drive, pull up high pressure fuel actual and desired pressures, fuel injection time or quantity for each cylinder, misfire data, and fuel adaptations. Do another flat rate test drive and review. Actual fuel pressure should match desired, a few hundred psi deviation is normal, if it's like 1000 or more that is a problem. If you have a deviation look into the low and high pressure pumps. Each cylinder injection time or quantity should all be very close to one another. A bad injector will have a higher or lower number than the others. Testing pumps or injectors will require more diagnostic time.

After I get another hour or two of time. Investigate the components that the data has led me to. It would most likely be scoping fuel pumps or injector amperage and finding the actual fault.

You have to have a diagnostic plan and follow facts and data, if you don't you spend piles of money on unneeded parts, nothing is cheap on Porsches. Unfortunately, diagnostics is not something that is really taught in mechanics school, it is up to the technician to learn on his/her own time, and very few do. I hope this helps and you get your car fixed properly.

[bjstare]

I must be crazy. That sounds like a textbook way to figure out what’s wrong with a car… yet that’s not what’s taught at school? The implication seems to be that throwing parts at a car is what’s taught at school? Lol. Go SAIT!

[Flexray]

SAIT doesn't set the curriculum as far as know. Apprentices go to school for 8 months over 4 years. They learn the bare bone basics of outdated technology. School is focused on teaching students not to burn down the building or drop cars on people. It is the technicians job to get and stay current.


Edit,
Here in Canada, we have a not bad training program. Europe crushes ours. But the US system is just a mess, their system is voluntary and full of anarchists. I have heard US shops will pay huge money for Canadian technicians.