stv

Hope someone can help me here.
I have a 2003 Cayenne turbo 4.5 with 63000 miles on clock.


I changed out all 8 coil packs and plugs for new as I was getting misfire codes but since changing I have once again got the P0300 as well as P0306 and P0308 codes which were different to the cylinders mentioned before the change.


The car is running terrible most especially when cold as it feels like it is about to occasionally run out of fuel with a severe lack of power and sometimes no power at all when I accelerate.
I also have the codes P0441, P2177, P2179, P2189.


I was thinking about changing out the purge vacuum valve in hope that the code P0441 would not come back but having read some posts from other members others are saying that their car is difficult to start when this valve fails especially after refuelling.
I never have difficulty starting my car which is making me think does this valve really need changing or is there another reason for this code P0441 appearing?


I have had a look around the engine bay for any obvious damaged vacuum hoses but could not see anything.
I have also removed and cleaned both MAF sensors and replaced both air filters.
I changed the Crankshaft sensor also as I was getting a P0335 code which has not came back since replacement.


This car is driving me crazy trying to diagnose the problem so any help relating to this would be most appreciated.


Thanks

wrinkledpants

It would really help us if you listed the code descriptions as you have a lot of codes listed. It's going to take anyone that wants to help significant time to search each of those codes to figure out what they are.

stv

The codes and descriptions I have are as follows:
P0300 Random multiple misfires
P0306 Misfire cylinder no.6
P0308 Misfire cylinder no.8
P0441 Evaporative emission system incorrect purge
P2177 System off idle bank 1
P2179 system off idle bank 2
P2189 system at idle bank 2

wrinkledpants

The misfires and lean codes are symptoms of some other problem. Your incorrect purge code is a problem. Since a failed evap purge valve can cause a lean condition, which can cause misfires, that's where I would start. It's somewhere on the front of the motor under one of the beauty covers. Not too difficult to replace.

A vac leak somewhere else will cause a lean condition. If the evap valve doesn't fix the problem, I'd start following all the hose connections after the MAF, including pulling the y-pipe to check for cracks.

stv

Thanks for your help Wrinkledpants.
I will replace this valve and update again once this is done.
I had a look at the position of this valve and you are right in saying that it should not be too hard to replace.

stv

Ok so today i replaced the purge valve vent line and although it was not too bad a job to replace, the worst part was separating the rigid pipe from the rubber hose. This was a real PITA!
Anyways i erased the codes and took the vehicle for a test drive.
The result: a slighter smoother running vehicle but still it felt rough with a hesitation in acceleration especially noticable when the engine was cold.
I checked codes again after test drive and got the following:
P2177 system off idle bank 1
P2179 system off idle bank 2

The previous P0441 has not came back after changing the valve so this is good news.

So obviously with the 2 lean codes i have now gone onto checking for vacuum leaks but can not see any evidence of this.

I now require some advice as to where i should be looking next to resolve this problem.

69gaugeman

Look up air oil separator or PCV valve. It's the big black round piece on the front of the engine cam cover on the driver's side. The diaphragm inside rips and gives a large vacuum leak. I used 4 layers of saran wrap to create a layer above it and it worked for six months before it hardened and broke. Now I have a rubber glove piece I cut as version 2. Will see how long that lasts. need to find a thin enough silicone sheet as version 3 if the rubber glove doesn't work.

stv

Thanks for your reply.
I will check out this pcv valve tomorrow and update once i do so.
I like your idea on the rubber glove.

stv

Ok so today I opened up the PCV valve and checked the rubber diaphram.
The result was no damage to it at all so this now rules this out as a possibility.

So far i have done the following:

Changed all 8 plugs and coils
changed air filters
changed purge vent valve
cleaned both maf sensors
cleaned throttle body
visually checked for cracked or damaged hoses with nothing obvious.

I still have the P2177 and P2179 codes showing lean off idle banks 1 and 2.
The car starts no problem but running is an issue.
When the engine is cold it feels like it is about to stall during driving and lasts about 20seconds before it smooths out again and during acceleration there is a bit of a delay in the car accelerating with occasional feeling of lack of power.
Could this most likely be caused by a fuel pump or fuel filter problem since having ruled out the above?

I'm hoping someone here can point me in the right direction where to trouble shoot next.

Thanks.

mcbit

Sounds typical of the symptoms associated with failing fuel pumps to me; a not uncommon problem on these cars.

stv

Thanks for your input.
What tests can I do to find out the condition of pumps?
I really don't want to be replacing pumps if it is not required.
Just had the car out for another drive today and the cel light came on.checked codes and still only the p2177 and p2179 codes present.

stv

Ok after clearing todays cel light I thought that i was not going to make it home.
The car was running terrible with a kangaroo like action and almost complete loss of power when accelerating.
This time when i finally got back home i plugged in diagnostic and up came 2 new codes.
P1145 O2 sensor bank 1 sensor 1
P1155 O2 sensor slow response bank 2 sensor 1

If my fuel pumps are failing, is it going to possibly trigger these codes?
I'm looking forward to hearing some opinions and advice thanks.

HansStuck

Are you sure your PCV valve is good? If not, it's going to be letting oil into your combustion chambers, and that could have fouled the 02 sensors.

I would consider checking that again, because if that is the actual cause/effect, your cats could be next.

stv

The PCV valve is definately fine so i know for sure this is not the problem.
i did wonder if the cats could be at fault as this evening there was a bit of an egg smell coming from under the car.
Anybody any other suggestions?

tcfs

Normally a rotten egg smell is failing cat converter.