lewisweller

Hi Thomas, if everything is new then I think time to review the history here, before the battery was a issue always going flat and you didn't drive for a while, so I think this might be a electrical communication issue rather than a assembly or mechanical issue as it doesn't make sense it failed just sitting outside for 2 years. Before doing anything else why not get out the battery charger and trickle charge the battery for several hours at low amp. Then reconnect and start the car (do some lock and unlock and key in ignition so least recognises it, clear codes and try again the shifter.

Guys it's the magnet position in relation to the circuit board I think. Either the magnet distance is too far from the circuit board inductive sensor or the magnet is weak and that plastic bit black cover piece needs to be changed. Maybe after years of use the Plastic sags alittle down and too far away from the circuit board? Also possible is the pin on the board that plug into the connector are not making proper contact but unlikely. Try to get another magnet from somewhere and run it manual under or over the circuit board to test the board is functioning. If that works then you know the board is not the issue as thomas found with his new board.

The code I not related in sure. The clunks may or may not be related to the psm warning but speed sensor is likely as you mentioned as specific speed, and no way 4000rpm is 6th gear at 60mph. So non rpm related would indicate its Road speed related which leads me to speed sensor first. What's the code related to the psm? Also don't rule out unmatched tyre pressure (rolling radius difference), different tyre types, tread pattern and or tread wear excessively different on same axle. You could jack up safely and spin each rear wheel listen for dragging noise, remove and clean speed sensors. Need more info to continue after that.

Which check valves do you refer to sir?

Ah simple fixes, some of us dream for these. ..........good for you mate enjoy.

Only used for cold start 20 seconds to heat up cat and dilute emissions briefly apart from that totally useless. I deleted mine both don't work. Throws a code occasional but no dtc and no affect on running. Just ignore unless you want spend money or are in cold climate and extremely environmentally conscious. Driving a v8 ha ha Lol. I stripped both mine apart and found to be full of soot because the check valve (see pic 1) from the exhaust connection was stuck open. I used a 3/4" metal GI end plug to close the rubber pipe and problem solved from leak. The fins inside will be broken and that's the cause of the code also if the motor is jammed or toasted the fuse will pop also. Pic 2 foam filter is like a lump of charcoal inside is toast.

All the pipes in the first pic below are either new or double checked. That T and its piping which runs forward to each valve cover is new 6months ago but when I had the manifold off a few weeks back I found it had oil and dirt around it where the metal pipes connect either side. Pic 2. I thought bingo it's leaking but not only was it tight as f*** to remove which I didn't get it apart, I tried to suck and blow to check for leaks and it was closed both ways which is strange. Oil and dirt but not leaking? Maybe it was dirt from before and the lazy buggers just refitted the new pipe without cleaning the grim off? Pipe 20 and 18 down to 7 and 6 what are these for? Pic 3 part no' 12 connects to the turbo vent pipes which goes down to a metal block thing 6&7 under each turbo. Pic 4 is the actual pipe in situ as I found it. Pic 5 is the actual metal pipe into that block thing.

I'm working on a theory and it is just a theory that my stutter under acceleration up to 4k rpm is my wastegate(s) flap either flapping around when it shouldn't be or being wrongly controlled during boost building. I dread the idea that this problem is the turbo itself having some mechanical problem and I really have gone through everything I can to try and hunt this issue down. So has anyone got any glue what could cause perfect idle and cruising running (fuel trims perfect, no codes, spark plugs read and look good, new coils) with great power delivery from 4k rpm up to redline but getting to 4k rpm is somewhat hesitant and kangaroo juttering??

Remember my picture in previous reply showing the T peice, if you had blown hard in that you would have found the issue yourself. Regardless Good fix mate glad they got to the bottom of it. Not to be critical but except the split in the rubber bit of pipe of diverter solenoid(change over valve solenoid porsche calls it) the other pipes probably had nothing wrong with them related to this low boost issue but as sometimes is necessary to find a fault you got to try a few things often at someone's expense lol. I thrown some dollar at my pig which has left me with some "working spares" shall we call them. Lol Function wise if anyone is interested:- The change over valve changes between vacuum and boost pressure as required to hold the dv closed with boost pressure and open the dv with vacuum when you lift off. The dv spring alone is only able to hold against around 8psi boost so the change over valve uses its reference boost pressure from the manifold to push against the dv diaphragm holding it closed. When you lift off the change over valve switches from boost to vacuum and quickly opens the dv by pass line back to the turbo inlet to prevent the turbo stalling and the car jerking around. I had a melted pipe that runs from the change over valve along the injectors of driver side bank to the front of the engine and T's off to each diverter valve. I had 0.4-0.6 bar boost and really jerky on and off throttle. After replacing the pipe and both dv I get over 0.8bar holding firm and lift off is smooth. At least with your new bits and bob's you should be good to go for a while. Happy motoring.

So assuming it is rotating and the noise increase and decreased per revolution? It got to be CV or front diff I think. By hand check the CV for back lash movement and in out movement play. The diff is harder to check.

This was an easy fix thank goodness. Found the little bit of connecting tube to the bottom of the n75 valve is split open (this is the positive boost reference from the passenger side turbo for the n75 valve used to open the wastegates hence overboost cos it can't open the wastegates without air pressure), I cut the pipe shorter to avoid it squashing the soft as sh*t pipe in the future. No codes now. Still stuttering lol POS pig.

Mb6 couldn't be the earth strap from the alternator to the chassis rail could it? Diagram alittle deceiving as to exact place. Also on the chassis rail a few inches away from the alternator strap bolt point is another earth point not used on my ctt. I wonder why it is unused?

Err well here it is the first code to pop on the problematic ctt P0234 overboost. Was driving to today and booted it a bit and felt flat to redline Wtf, almost like the variocam didn't switch to high lift because the boost gauge said +0.8 bar still as per spec. So I whipped out the trusty v-checker which is always in the temperamental Pig in case, and it shows the P0234 code. I know the possible causes and have read a lot of posts of this code but not found any with fixes except loose piping broken piping which at the moment I'm thinking I don't have any (all bloody new). N75 valve is new, MAP sensor is original but I've cleaned it today and before it didn't make any difference then or now. Turbo problem possible but unlikely I think. So what does that leave? If I clear codes it won't return in short run but did after many Km today return and cleared again. No here is the only interesting thing about it, when the code is active it goes into a limp mode flat performance and the stutter hesitation I suffer with since I got the car goes away and it drive smooth but slower of course. I clear the code and get boost back but also the kangaroo stutter stammer acceleration. If I disconnect the map sensor exactly same result but a difference code like P???? Underboost which makes sense. So guys what makes a turbo engine do this?

Hi John, I didn't twig this earlier but yes the earth mb2 is under the wheel arc cover along with some other electrical connectors. You can just unscrew the front portion and flop it back to access these electric and also the DV if you wanted to pop it out and have a check whilst your there. I just did alternator twice (don't ask why) and I had a good look at these electrical stuff whilst in there to make sure earth was tight no corrosion etc. See picture of the view with wheel arc flopped back, to the right upper corner of the intercooler you will find your earth and connectors.

I second the chance it's a pcv vacuum hose or pipe leaking and probably opens up as the engine warms up and idle decreases. Don't rule out your AOS diaphragm split, check valves all around the front intake area and the two at the rear of the manifold, cracked flexi piping between bank 1+2, throttle body gasket and throttle body dirty, manifold gaskets or cracked split intake Y pipe ..............the list is exhaustive. Also I assume your oil is clean and regular changes? Plugs and coils is good condition and no cracks down the sides of the coil pencil stem? I changed a lot of stuff on mine from just old age and Wear.

Interested to know what your running problem symptoms were? I got no codes ever to follow but still have a temperamental running issue of hesitation and stutter, startup, idle etc is perfect and wot is pretty good also up at high rpm but through 1k-4k its jittery kangaroo most of the time and even like it in neutral or park just revving you can feel at certain rpm's it's not happy.

Thanks for the advice. I do feel the Cayenne AC even when cool does feel somewhat uncomfortable and know you mention humidity I think your right. Other cars ac like my audi or my dad ford Explora and every Nissan I've owned feel cool and dry, the Cayenne I always feel sticky.

If shaking steering wheel or braking makes it go away then sound like pad on disc touching an edge, worn caliper bushings, backing plate cover rubbing. But a clunk in the mix doesnt sound like brakes to me. That's more likely a CV joint or front diff. A worn wheel bearing clunking would at low speed would be a very bad noise at higher speeds cornering under load etc. Start with brakes, get the noise going and don't steer or accelerate just very light touch the brake so vehicle speed does not really decrease but pads and disc make contact if noise stops you got your way forward.

I am not exactly convinced either with the diagnosis. The AC does blow quiet good if park underground or out of the sun below the magic 37oC I would say is manageable. But it still has this occasional temperamental issue when it will kick out the cooling and start blowing non cooled air (not hot air like the flap moved) with a bit of musty smell and it will do it if I idle for a while and then rev the engine or drive off. Have to off on the AC to get it to kick back in again. I think overall the cayenne AC is alittle under powered for the middle east, heating is great mind lol. Its winter now and I will just manage it for the next 6 months.

Cayenne v8 doesn't like lpg or high Ethanol fuels like 10% or 15% mix.

+1 alternator is fudged. I just went through the pleasure of installing a. Delphi recon alternator £140 which failed mechanically after two days, total junk rubbish inside....... never again. If the shop did bearings and slip ring, the real weak point aside from mechanical wear is the regulator pack, it will breakdown intermittently and output will drop, new battery would have masked the issue temporarily. In the end I bought a new Hitachi unit from amazon for £585 and got it sent to me in UAE from UK for £70. Don't rule out the ves but for me alternator is my diagnosis assuming you check all the obvious connections for tightness and corrosion.

More driving and more interesting things, the engine definitely is more happy running, the short term fuel trims are -0.8% on both banks and long term fuel trim on bank 1 is -2.1% and bank 2 is -3.0% so pretty good! But, and here it comes......... if I idle it for some time do some traffic stop start and slow plodding around like today it really doesn't like it afterwards. You go to blast it out and it's a bit fumbled and hesitant, but if I'm blazing on the highways and good pace it's loving it. Very strange behaviour. Anybody have any ideas what this is?

Went to garage today, the gauges showed the low pressure side was too high and the high pressure side was about right. The technician said it is either the refrigerant is over charged or the compressor is weak and would need replacement. For the hell of it I said let's evacuate it and refill to spec 1050grams. He evacuated only 700grams the first time which was strange, he then refilled with 1050 and it went hot meaning something was wrong. He evacuated it again and took out 1400grams this time meaning the extra 350 grams was left from the first time. Now he refilled again to 1050 gram and the AC was Ok (low pressure side gauge still reads alittle too high) cooling ok but not winning any medals in the middle east. I think the summary of this is unless something else is the fault, its the compressor which is worn and weak? Welcome any advice or experience pls I'm by no means an AC expert, quite the opposite.

The AC is still poor in my opinion it can't Co with + 40oC heat, it also will cut out the compressor sometimes and have to turn it off and on a few times to get the thing to kick back in cool. Anybody have a cayenne with AC that stops cooling when ever it decides to??

Best update this thread, the check valve above is not leaking. After new Alternator and new battery under warranty the car is running better, I will put some more km's on it before being sure as it's behaved well before and then became a stuttering **** again shortly after I announced a self healing miracle had happened.