Hi everyone, just joined after buying my first (2003 955) Cayenne Turbo yesterday and this seems to be the most active and most knowledgeable Cayenne community on the net.

Sadly, my first post is in the form of a desperate plea for some knowledge

I went to collect my Cayenne in response to an ad from over 300 miles away, apart from being in need of a new battery, the car seems in great shape with plenty of bills and full service history to show it has been looked after in it's 140,000 miles of use. I bought it and took to a local place to replace the battery and set off home.....

Everything was going great until around half way back when during an overtake on the highway (I floored it), there was a complete loss of power. I managed to limp to a safe place and took a look. It will start and tick over perfectly, but when trying to rev nothing happens except some backfiring. It is possible to drive very slowly by just touching the throttle, but any further pressing causes spluttering, jumping and dying.

My initial thought is that I have popped off or split an intercooler hose. I can't see any problem in the visible areas (near the intake plenum), and can't hear any unusual sucking or blowing noises when I try to rev it but had no tools with me to strip things down further to investigate.

I'm returning tomorrow (Sunday) to where I left it (2+ hours away) with tools, but I guess what I'm asking for is a little insight to whether you guys think I' m guessing the problem right (or any other alternatives?) and whether there are any common weak areas on the boost hose/intercooler side of things to check first?
I did have a little bluetooth OBD device with Torque with me, but no errors are shown as stored (in this limited way!) and no warning lights appeared on the dash. I will have an iCarsoft with me tomorrow to check further.

Would a catastrophic boost leak like a popped hose cause the symptoms described and also not throw up an error or engine warning light?

Any thoughts would be hugely appreciated!

 

Did you find anything? I think you're on the right track with an air leak. My 996 Turbo exhibited the same symptoms, it was a small intake leak just after the MAF, before the Turbos. The engine was receiving extra, un-metered air, so the ECU went into limp mode to protect the engine.

 

It wasn't in the end, I got some helpful advise on a different forum and went back and unplugged one of the MAFs. This put the vehicle into a limp mode and I drove it home with no further problems.
Once here, further investigation showed that the r/h MAF had packed up and needed to be replaced.

 

Glad you figured it out and it wasn't too major. Sadly I just had the same thing happen to me on the way home tonight. Went to exit the freeway and it started coughing and almost died. I made it about half a mile to the first place to pull over but once there it was idling just fine.

I limped it the mile and half or so home. Same symptoms as you, idles fine but coughs and backfires if I try to rev it. I'm going to head to the parts place right up the road in the morning and try some MAF cleaner.

 

Sounds like the same symptoms, yes. If it is, unplugging a MAF will enable you to drive it remarkably well, I'd say at about 90% with just a little loss of smoothness.

Now I've looked into it more, I'd say MAF cleaner almost certainly won't work, if you want to test a MAF, here's what I did:

Going to each MAF are four wires (once you peel back the covering). Into each I carefully inserted a needle so I could test it with a multimeter making sure there's no way the needles could touch each other.

On mine (don't know if yours is different), I have a green wire that is 12v negative, a thick black that it 12v positive, a thin black with yellow trace that is 5v positive and a thin black that is the variable positive. On the old non-functional MAF, the voltage of this thin black wire would remain a little over 1v regardless of engine revs. With the new one at 3000rpm the voltage increases to a little over 2v.

If you want to replace them, Bosch have helpfully written (as the do with all their parts), their part number on the body of the MAF enabling you to buy from a Bosch dealer at a fraction of the cost of buying the exact same item from a Porsche dealer in a different box In my case it was 0280218071 which are about £70 from a Bosch distributor, or £350 from Porsche....

 

Well I took mine out and cleaned them. Put it all back together and it didn't fix the problem. Unplugged them and that still didn't fix the problem. Now when I start it it seems to idle ok but a little rough. But if I try to rev it or put it in gear it dies. Now I'm thinking more like fuel pump.

It hadn't thrown a code yesterday but now it is so I need to fire up the Durametric and see what it's saying.

 

I did receive a suggestion that a fuel pump failing would give the exact same symptoms, here's what the guy said if it's of use to you:

"I'm with the feeling that it's intercooler pipe related but if failing that and by weird chance tomorrow it starts and drives fine then probably a failing fuel pump (had it on our old mk1 S and the symptoms you describe are identical).

Make sure there's at least some fuel in there and one trick you can do is pull one of the fuel pump fuses out which forces the other one to run constantly (rather than how the system works in practice), of course you need to establish which fuse kills the good/bad pump and remember that as the tank is humped and you are only sucking off one side the range will be very reduced.

The system should prime when you open the drivers door regardless if ign is turned on or not and you will hear it the pump in the o/s of the tank go bzzzzzzt.

With our car the pump in the o/s worked and gave the prime to pressure the system when the door was opened and the engine would start and run but as soon you tried to add power there was nothing there and it would die, the n/s pump was faulty.

If it is the pumps don't by Porsche ones as the VW Touareg is the same and they are available for about $50 each from eBay in the USA

Also if it is fuel pumps then they give no error codes or check engine light"

Good luck!

 

That's pretty much exactly what mine is up to now. It will fire off and idle ok, but a bit low it seems, but then if you try to give it any gas it'll die. Or if you just let it idle it will die before long. I'm going to try pulling the fuse a side at a time and see if I can isolate it to one side or the other.


Looks like ECS has the whole package, both pumps, regulator, filter, and gaskets for about $650. That right side looks like a MAJOR pain in the *** to get done though.


Called a local shop but they can't get it in until next week. Gonna call another one tomorrow, if he can't get it in I may bite the bullet and try to get it done myself.


Fun, fun, fun!!

 

Well the only other shop in town that I'd trust to work on my Cayenne said they could fit me in oh, somewhere towards the 1st of July. I ordered the replacement kit from ECS but it doesn't look like it'll be here by Friday. I'm hoping but it looks more like Monday. Would have hoped to get it here Friday so I could work on it over the weekend.


We'll see what happens I guess!

 

Working on your own car is half the fun!

Let us know how it goes, I'd be interested in the process. Bound to need to do myself one day I imagine!

 

Pelican had a pretty good how-to on the fuel pumps. Looks like the only hard part is the passenger side there are a lot of lines and hoses to contend with and not much room to get your hands in there.


Well for the first time ECS let me down, some of the parts for the kit won't be available until next week. I've been thinking about it all day long and am tempted to just take it in to the shop that I haven't cancelled the appointment with for Monday yet.


I generally don't mind working on my own cars. I've done all the work to this one too so far. I'll make up my mind tomorrow but am leaning toward just waiting on the parts and cancelling the appointment.


I am slightly miffed at online companies though, just went through this with Tirerack last week. Apparenlty "in stock" does NOT mean they have the wheels in stock. Weird. Now ECS not having all the parts of the kit. I guess it's the new normal.


But hey my new wheels and tires arrived today so it'll look good with new kicks....just won't be able to drive anywhere!!


It's all good I just hate wasting money on a rental car when I should have bought a second car to have around just in case.

 

Oh, and sorry for pretty much totally hijacking your thread. Thanks for sharing!!

 

So hopefully ECS ended up coming through after all. Sounds like the parts will be here Monday (technically today but I'm just heading to bed). I also played with it a bit yesterday and it seems like it's the left pump. Pulled the fuse on the right one and it acted the same still. Pulled the fuse on the left one and it started and idled ok and would rev. So I'm starting with the left one.

 

Nice one! Well I think half the problem with electrical issues is the diagnosis, they can lead you a real merry dance sometimes especially when intermittent.

Sounds like you've figured it out, just the small matter of doing the job

 

The baskets and lines are the same, but do we really know if the pumps are rated the same? No, we don't. Do we really know if the part #'s on the pumps are the same? Nope. OEM Auto engineers like to use the smallest pumps possible to reduce unneccecary circulation and heating since gasoline boils @95° f. This is one of many reasons why many mfgs are moving to pwm controlled pumps and a controller. Seeing that there is a 200 HP power difference between a Touareg and a Turbo S, an educated guess would be that they are not the same pumps. Course, there is no fuel press. sensor on the 955 so the computer will not know if pressure is low and will just reduce boost and retard timing to richen it up. I drove around on one pump forever until it to died and left me on the side of the road. I experienced no ill characteristics other than a reduction in power. If someone wants to use Tuareg pumps in the Cayenne that's fine but to come in and say they are the same when it was read somewhere else isn't cool. I think there is enough misinformation about the Cayenne already. Please, please, have some supporting evidence for claims made.