2003 Cayenne Turbo major running problem

[stv]

I need some desperate help here with my 2003 Cayenne Turbo.

I usually run this car on super unleaded 98 or 99 octane and the other day filled it with standard 95 octane. Around 70 miles after filling up the car started running very rough to the point that i thought i was going to break down.

the vehicle had no power and the transmission was jumping around between gears not knowing which gear to remain in.

there was also quite a loud kind of slapping or knocking sound coming from what I can only assume is the transmission.

I came to a hill and could hardly even go up it and could only drive like 10mph.

I was convinced that this lower octane fuel has upset something

The vehicle has 66000 miles on her and has just had oil change, filter change, new plugs and coil packs.

The cel light was on so i checked for codes and pulled up the following:

P1145, P1155 and P0234.

Now prior to all this happening I did have an issue with a vacuum leak somewhere that was causing the cel to come on but could not find a leak anywhere.

The vehicle is now almost undrivable and I would really appreciate any advice on what to look for here.

I did also add a treatment of octane booster to the remaining half tank of fuel but no noticable difference to report.

[hahnmgh63]

17553/P1145 - Mass Air Flow Sensor (G70): Short to Plus

Possible Symptoms

• MIL on

Excessive smoke from Exhaust

Reduced Engine Output

Possible Causes

• Fuse or Wiring Harness Issue

Failed Mass Air Flow Sensor (G70)

Possible Solutions

• Check Fuses and Wiring Harness, see Factory Repair Manual

Replace Mass Air Flow Sensor (G70)

 

17563/P1155/004437 - Manifold Abs.Pressure Sensor (G71): Circ. Short to B+

Possible Symptoms

• Limp mode

Possible Causes

• Connection(s) to/from Manifold Abs.Pressure Sensor faulty

Manifold Abs.Pressure Sensor (G71) faulty

Pipes/hoses not/wrongly attached

Possible Solutions

• Check wiring and connections

Check / Replace Manifold Abs.Pressure Sensor (G71)

Check pipes and hoses

 

16618/P0234/000564 - Boost Pressure Regulation: Limit Exceeded (Overboost Condition)

Possible Symptoms

• Malfunction Indicator Light (MIL) ON

Boost Pressure too high

Reduced Power Output

Possible Causes

• Hoses incorrectly connected, disconnected, blocked or leaking

Boost Pressure Control Valve (N75) faulty

Boost Pressure Sensor (G31) faulty

Turbo Charger stuck/faulty

Possible Solutions

• Check Charge Pressure Control System
  • Perform Output Test (to check the Turbo Charger)

• Perform Basic Setting (to check the Charge Pressure Control)

Perform Pressure Test to locate Leaks

Check/Replace Boost Pressure Control Valve (N75)

Check/Replace Boost Pressure Sensor (G31)

Check/Replace Turbo Charger

[hahnmgh63]

Since all of that work has been done recheck all of the hoses and wiring connections. Moving around those plastic lines can cause cracks as they get real brittle after a few years with age & heat (cheap plastic).

[wizard]

In addition to the above, I would fill the tank with higher octane petrol (Shell Racing 100, for instance) in order to rule out (or in) that the slapping/knocking sound you heard was engine knock arising from too low an octane for that turbo engine.

What octane is recommended for your car ?

[stv]

Thanks for the replies to my thread so far.

The octane I have in tank at moment is 95 and the vehicle handbook does state that vehicle is run at optimum performance on 98 octane however a minimum of 95 octane can be used and the vehicles knock sensor will adapt the timing to suit.

Is it possible that the knock sensor is knackered?

I'm considering draining what is left of the tank and refuelling with higher octane as mentioned to rule this out.

one thing I did notice was excessive smoke from the exhaust.

[wizard]

Excessive smoke. P1145. MAF ?  A forum search will describe the symptoms ...... and the cure. 

 

Maybe that's the first thing to check.

 

Given that 95 octane is permissible, I wouldn't drain the tank but would add 98 octane .... not 100.

Edited February 28, 2016 by wizard

[stv]

Excessive smoke. P1145. MAF ?  A forum search will describe the symptoms ...... and the cure. 

 

Maybe that's the first thing to check.

 

Given that 95 octane is permissible, I wouldn't drain the tank but would add 98 octane .... not 100.

Thanks for your help.

I will try adding the higher octane and report back with outcome.

[wizard]

On reflection, I don't think petrol is the issue.

I have read that a faulty MAF sensor can also affect shifts in the automatic transmission, as you described.

Cleaning or replacing the sensors (two in your case, I believe) is not particularly difficult provided great care is taken if you should decide to clean them as the first step.

[stv]

Thanks Wizard,

Ill try cleaning both sensors and see what happens.

Watch this space for update.

[mattehlers]

I wouldn't worry too much about the octane. Mine runs fine on 87.

[stv]

Ok, so today I had both MAF sensors out and cleaned them with maf cleaner.

Reinstalled and engine still runs like crap.

I didn't even try taking it for a test drive as when it was idling i revved it hard and it sounded very rough. As well as that the engine revs would not go above 4000rpm whilst in park and with my foot hard down on accelerator.

Does this lack of engine power narrow down any of the likely places I should be looking for the problem?

I still have just under half a tank of fuel of the 95 octane and have not changed this out yet.

Does anyone know if it is possible that the knock sensor on my vehicle may be knackered (technical term) and if it is knackered its therefore unable to alter the timing to suit this lower octane fuel resulting in the terrible running engine?

One other thing I will mention is that there appears to be a leak from both exhaust pipes about half way along the underside of vehicle. This leak is coming from the joint of the two pipes directly in line with the front doors. Strange thing is when I started the car I could clearly see exhaust gases escaping from the connection flange on both driver and passenger sides along with some water or condensation dripping from the joint but after the engine had warmed up for a while this seemed to stop, hmmm is this normal? Or should I be looking to remove the connection flange and seal properly?

I really don't want to have to book this vehicle in to my local Porsche centre so some more advice from anyone would be great.

[bigbuzuki]

The 4000 rpm limit is normal if the lever is in Park.

[wizard]

Good morning, stv.

Firstly, the MAF sensors. Might I suggest that you clear the codes, run the engine again and see whether 1145 comes back. Are you still getting excessive smoke from the exhaust and, if so, what colour ?

Obviously you need to seal the exhaust leak. Condensation from the exhaust is normal until the engine has heated up.

Your oil is presumably the normal colour ?

[stv]

Good morning, stv.

Firstly, the MAF sensors. Might I suggest that you clear the codes, run the engine again and see whether 1145 comes back. Are you still getting excessive smoke from the exhaust and, if so, what colour ?

Obviously you need to seal the exhaust leak. Condensation from the exhaust is normal until the engine has heated up.

Your oil is presumably the normal colour ?

Thanks Wizard.

So far i have now cleared the fault codes and turned off the cel light.

The vehicle does seem to run a bit better but i have only had it on a quick test drive for a couple of miles. I'll have it out today for a longer drive and see what happens.

I have not sealed up exhaust yet but I will.

The exhaust does seem to be excessive smoke and is white in colour. The oil is normal colour so nothing abnormal there.

I'll update again later today after driving vehicle for a while longer and see if this cel comes back.

[stv]

Ok so latest update today is I have put approx 100 miles on to my cayenne since cleaning both maf sensors and clearing faults.

I also fuelled up with shell v power to give peace to my mind over the last batch of inferior supermarket fuel I added and 100 miles later no cel has come on and vehicle appears to be running perfect. Now call me paranoid but I just cant help thinking this cel light is going to come on again.

I'm sure the cleaning of the maf sensors has resolved this running issue though and hope it wasnt coincidence.

One thing I cant figure out though is that if cleaning the maf sensors has resolved this then could these previously dirty sensors also have been the cause of the other codes p1145 & p0234 previously getting triggered?

[wizard]

Good for you, stv.

I'm not a technical person, but I would imagine that your exhaust leak will be affecting the oxygen sensors in the exhaust which then affect fuel/air metering ....... and boost ? I'd get the exhaust sorted sooner rather than later.

Happy motoring !

[stv]

Good for you, stv.

I'm not a technical person, but I would imagine that your exhaust leak will be affecting the oxygen sensors in the exhaust which then affect fuel/air metering ....... and boost ? I'd get the exhaust sorted sooner rather than later.

Happy motoring !

Many thanks to all who who replied.

[lewisweller1982]

Hello I've got a CTT 06 112,000km (with E81 power kit from factory) and had a load of issues since I bought it.

So far I've had Head Gaskets/water pump done at a German car specialist useless bunch I might add, I've done new plug/coil packs & air filters, Purge valve replaced, throttle body cleaned, various PCV and leaking vacuum pipes from Change over valve to Diverter Valves fixed (replaced one dv as well and check the other ok), found Secondary air Injection pump full of soot because the check valve from exhaust is stuck open, you hear a thumping pulsing sound if the check valve is leaking back hot exhaust gases (blocked the pipe off as hot climate don't use the SAI anyway) and done a load of maintenance jobs.

 

From my Automotive Degree background and unlucky streak I've done a load of research and still I have some lumpy misfiring acceleration up to 4000- 4500rpm then it flies in any gear. So I am also left with the prognosis that maybe my MAF sensor(s) may need a clean. no fault codes and boost is great 0.8+ bar, idle is smooth as well.

So I've ruled out fuel pumps, filter and injectors (always use 98-99 super), ruled out boost/vacuum/PVC leaks, ruled out DME "programming as with PSM off it is a little better but doesn't fix the issue like many with "hesitation problems" have reported, so back to the MAF sensor for me.

 

 

Back to your post the MAF sensor would need 15 mins at idle and some driving WOT to relearn and calibrate itself, plus you switched the octane back to 98-99, taking this into consideration it may be making sense the issues went away after 100 mile was clocked up.

 

Do post back if the issues return, us CTT guys need all the collective help and shared knowledge we can muster. :)      

[lewisweller1982]

Update, just cleaned MAF sensors (they weren't dirty) and not a lot changed if anything at all. Back to the drawing board for me. out of interest anyone know of running issues caused by low or lower than normal charging system voltage, I am working on a theory that my "Check tail light" warning (I have a Porsche dealership 2008 facelift which includes LED combination tail and brake lights) is related to voltage as I've checked everything 100 times and they work fine unless my foot is on the brake then I open a window or increase the fan ac speed then boom the warning pops up. Strange.... penny for your thoughts Sir. 

[bigbuzuki]

Measure your charging voltage at idle and report back.

[lewisweller1982]

BIGBUZUKI

 

The voltage at idle is 13.8-13.9 when the AC is on it drops to 13.1-13.2 and at that voltage the warning "check tail light" will appear every time. AC off and no other electrical loads and it wont trigger the warning.

So is my alternator really that bad or is my CCM overly sensitive to a lower voltage and thus triggers or possibly im not getting all that voltage through the CCM maybe so the drop is more significant ?

 

I cleaned the earth at the rear right  of the boot where the CD changer and AIR suspension control module is located, it was not corroded and not loose. I also removed the main earth strap from battery where it bolts to chassis just in front of the drivers seat. again not corroded and made no difference except the car runs like a total turd now, so another 500km of DME "learning" required. it was almost getting better RE my stutters and splutters at around 1800-2500 and 3000 and 4000rpm.

Will this nightmare ever end lol drama  

[bigbuzuki]

Voltage from alternator seems normal.

Reseat fuse that supplies power to the comfort control module.

Try reseating the electrical connector to the CCM as well.

Also reseat the tail lamp electrical connector assemblies.

Do you have the original rear tail lights without the LEDS still available?

Try plugging them in to see if it is the light assemblies causing your issue.

Edited May 25, 2016 by bigbuzuki

[lewisweller]

I don't have the original tail lights from the 2008 face lift. I did get some warnings directional light and licence plate too when I did a lot of on off engine trips during a night shift at site. I left the engine running the rest of the night after that.

I'm on holiday now so can't try the suggestions you made until July. But I'm leaning towards revision 4 ccm and coding to solve once and for all.

On another running related theme, I pulled my dip stick out with engine running and idle did not even bat an eye lid. I was expecting to see a cough and idle dip but absolutely nothing. Could I still have vac leaks despite very stable idle of 500rpm and no fault codes, no noises of sucking etc?