Well I wish I had done a writeup with pics, but I was unsure that it would benefit any and actually that it would not hurt.
So I am going to share my experience and keep it short and sweet.

Recently the Cayenne has been running a bit rough and seems to be lacking in power and mpg. Then about a week ago I started pulling a code for "system too lean at idle, bank two." I think its a po2189? I didnt save the # before I erased so don't quote me. I just replaced all my plugs and I know that the coils are good. So I decided to give cleaning the MAF's a shot.

First of all DO NOT use anything other than CRC MAF cleaner.
Second, do not touch the spray tube to anything on the meter itself. Use some common sense and a gentle hand and do not blast like a maniac.

It is a pretty straightforward process and not difficult at all.

Start by removing all the side and front engine bay covers.
Do one side at a time.

Remove the airbox cover and remove the filter.

Unplug the MAF.

Loosen the screw clamp that holds the MAF housing to the lower plastic accordian tube that leads to the turbo intake. This is the most difficult part. The tube is hard plastic and not very pliable. It is a tight fit. I recommend grabbing the tube with one hand and pulling up while wiggling and working the MAF housing out with the other. A flat blade screwdriver may be of some help to separate them but DO NOT pry between the tube and the MAF housing. You could break the housing, but will likely stretch the plastic tube and then your seal is compromised.

Once you have the MAF housing with UPPER tube assembly out, it's time to remove the MAF unit from the MAF housing. The unit is held in place by two 5 point security star headed screws. This isn't a problem. Take a file and file a flat spot on the side of each screw head. Two opposing flat spots on each is even better. Get yourself some mini, quality, vice grip pliers. Grip the screw head utilizing the flat spots, and unscrew them. You could replace them with a screw of a different head but I did not. Gently twist and remove the unit from the housing. There is an o-ring on the unit that will make it stick a bit.
On the unit there is a diode that is exposed, be very carefull and do not touch or damage this diode, or the wire. Take the CRC MAF cleaner and clean the END of the unit where the sampling wire is. It is buried inside the unit, you will see. There is also a hot plate adjacent to that that needs to be cleaned as well. Also clean the diode. Sling out the remaining fluid from the unit. DO NOT blow out with compressed air or touch anything inside the unit. The cleaner dries really fast so there shouldn't be any issues.

Re-assembly is the reverse of removal. Be sure to spray out the MAF housing as well. Mine did not appear dirty at all. Neither the unit or the housing. A LIGHT coating of dielectric grease on the unit's o-ring will aid in assembly and seal.

I removed the ecu fuse in the engine compartment for a couple of min. so that the computer would relearn.

Do the other side the same.

As a result of this, the trouble code has not returned after 3 days and multiple start/stops each day. The engine runs MUCH smoother and has what I would guess to be at least 25 more hp. The exhaust note has changed and feels and sounds as if there is more advance in the timing.
Fuel mileage has noticeably increased, though I have not done the math to confirm this. ( I don't trust the display) Idle speed returns to specs quicker and is more stable.

 

Thanks for the write-up, I will give this a shot as well. I'm also replacing the six coils that Porsche would not replace under that supposed new bulletin where they would cover the faulty coil issue (only replaced two under warranty). I am also installing NGK iridium plugs while I'm in there, see how these changes affect my less than stellar MPG I'm getting.

 

Good write up.

I have the same issue. I unplugged my mafs the other day and went for a blast. felt very little difference with unplugged mafs, that would suggest one or maybe are knackered.

 

Yes- when u unplug the maf's, the ecu goes to open loop. Which means that its operating the engine based on preset parameters and not all the real time data that it needs. Open loop settings are generally on the safe side as far as tune(afr,timing) is concerned.

 

Good to see someone who knows what they are speaking about. I used to flash cars in my spare time and cane across plenty of cars with dodgy mafs, unplugging them was a quick and easy way to diagnose them

 

How many miles were on your CTT when you cleaned the maf???

 

Mine has only done 23k miles and there is deffo one not right.

 

I have about 85k miles. On a side note has anyone ever changed the 0² sensors on their pepper?

 

Enter Content

 

what is a MAF ?? any pics

 

MAF - Mass AirFlow sensor. MAF. Pronounced "M-A-F" and the V8 has two of them.. to either side of the central intake on the engine. IMHO one of the silly parts of a Cayenne design since both feed into the same intake (they could'a done the same thing at half the expense by having a single MAF at the intake..) 'duh. IF there were two intakes it might actually make some sense.

 

so what was the fuel usage difference on the dash gauge before and after?

 

Everyone I know pronounces it "maf" like jumbling the end of "math". This includes mechanics. So, you likely can't go wrong either way.

 

Holy thread revival!!!

That's a generous first post!

 

Maybe it's a Joisey thing? Everyone I know just says Maf too.


Yep I'm sure those two guys who asked what a maf was were still waiting for an answer.