Is this the Techron cleaner I should be getting or is there a better variant?

https://www.amazon.ca/Chevron-65740-.../dp/B00092893E

 

Sorry - yes - I meant 957, but my fingers typed 958 (BAD FINGERS! BAD, BAD, BAD..)

 

That's it. You want the "Cleaner" - they make a more diluted version meant for "regular" use (X tanks per bottle).. but this is the stuff which will hopefully clean it up.

One problem you might be running into - a common problem that's developing with direct-injection engines (where fuel is squirted directly into the cylinder, not into the intake path) - is carbon on the back of the intake valves. It used to be with intake injection - the gasoline had enough cleaner in it that it cleaned the back of the valves as it flowed past into the combustion chamber. That doesn't happen with direct-injection.

The only real way to determine if that's a problem is with a video probe - sent in through the throttle-body opening on the intake, and down the intake runners to look at the backside of the valves.

If there is enough carbon built up, it can disrupt the air intake path and created turbulence causing crappy running.

Cleanup on it isn't simple. And eventually I think all direct-injection cars will see the problem, but particularly turbos since the turbos have oil circulating through their bearings, and some leakage into the intake is almost a given.

Cleanup techniques I've heard of being used -

> Walnut blasting - where crushed walnut shells are blasted at the back of the valves (with the valves closed and the intake manifold removed), then vacuumed out. Sort of like sand-blasting, but the walnut shells won't damage the surface finish on the head or the back of the valves.

> Cleaner injection into the intake. This uses a pressurized bottle of solvent, something like Techron that's sprayed into the intake when the engine is running, then the engine is quickly shut down, with the idea being the solvent is soaked up by the carbon and next time you start the engine up the carbon will fall off and be pushed through the combustion chamber.

Dunno how well this works, except anecdotally, I used it back in pre-direct-ignition days on a BMW that had carboned up valves due to the gasoline of that era. It did leave the back of the valves spotless. The local NAPA dealer had a kit they rented out to do it - the customer bought the canister of pressurized cleaner, and in this case - hooked it up in place of the fuel supply, and ran the car off it until the canister was empty.

Both these techniques were used in the past back before Tier-1 gasoline standards were put in place, requiring a certain amount of cleaner in the gasoline itself (that was a BMW thing - since they had the biggest problem with US gasoline quality at the time.) Both were pretty effective.

Of course head removal and disassembly and cleaning could also be done, but it's likely to be rather expensive.

 

More info - well presented - on intake valve carbon crud..


Happily - sorta - on the V8 Cayenne engine, it's not a huge deal to pull the intake to get to the back of the valves.

 

There is a vacuum line that goes into a white plastic T right up against the fire wall that is prone to cracking. I would thoroughly check yours out and make sure its not broken. For instances on my 50k mile Cayenne Turbo all I had to do was breath on that plastic vacuum T and it fell apart into a bunch of pieces. If you are for sure your vacuum lines and T's are 100%, when was the last time the oxygen sensors have been replaced?

 

is this the vacuum line you are talking about?
This was exactly the reason for my problems.

 

No, mine is different. Here is a picture of it with the plastic white T removed but it went here (in red).

 

I know many will laugh at this, but how old is your battery?

I had this exact issue on my 09 CTTS in early 2016. The car would shutter or choke a little bit at random times, wasn't sure why. First at lower RPMs, then at upper RPMs. Car always started perfectly, runs very strong, but would occasionally sputter and I could not wrap my head around the problem. It was showing no other performance issues whatsoever.

I too replaced the coils and a lot of other "stuff" thinking I would fix it. No luck. I put fuel cleaners in, no difference.

Finally one morning I decided to put a new battery in as part of preventative maintenance. An interstate battery dealer recently set up shop near my house so I picked one up. I swapped the battery and the stutter has been gone ever since. In fact, since changing my battery - I am shocked at how the car has come to life. I didn't realize how a weak battery was affecting so many things in my Cayenne. Odd things were happening with PCM, door locking etc. I know you didn't list those items as issues, but checking your battery may be worth your time.

It may also be worth dumping a big jug of Sea Foam in your gas tank during a fill up, drive it for 100 miles or so and see if the injectors are the issue and the seafoam will free them up/clean them up for a bit. If the seafoam trick shows improvement, most likely your fuel injection system/injectors. I've done this before as well and put Sea Foam in my fuel about once a month just to keep things clean.

 

I`d be very surprised if carbon build up is the issue as the car had a new engine under CPO just before I got it - can't remember the figures but it only has around 20,000 kilometres on it

 

So there were codes and they pointed towards lean running?

 

How hard are these plastic Tee`s to get to - does it require removing anything?

Not sure when the oxygen sensors were last replaced - if they were failing would that result in the symptoms I describe? Is there anything I can look at on Durametric to help decide if this is the issue?

 

Is that picture from a 957?

 

The battery is just over a year old - I changed it shortly after I got the car to ensure the random codes I was getting for 4WD faults etc wasn't the battery dying (it wasn't - it was the infamous transfer case motor that had went south)

The battery seems strong (no fault codes, car starts fine etc) so I don't know if it makes a difference that its slightly smaller than the original (I remember when I put it in that it didn't fill the space that the original battery came out of)

 

Sniffer, did you get this figured out, sounds like symptoms I am have in on my 05 CTT. Thanks