Rough Idle on 2008 Cayenne S Resolved

[chucklong]

I have a 2008 Cayenne S with 70k that is stock.  Four months ago, I came to a stop at a red light and noticed the idle was rough.  Initially I thought it may be bad gas so I got some fuel injector cleaner.  Then the CEL came on.  I pulled the codes with my Durametric software.  No misfires, just Bank 1 P1371, P1351, and P1352 codes.  Did a scan on this message board for the topic.  I ordered a new valve lift actuator and replaced- No change.  I took the Bank 1 actuator and installed it on the Bank 2 side- No change.  I replaced all the spark plugs- No change.  Changed the battery- no change.  Cleaned the intake valves with a bore brush-No change.  Cleaned MAFs and TB-No change.

 

Other than the idle and CEL, the truck ran fine, had great power, and got normal mpgs (19 on hwy). 

 

Frustrated with not being able to diagnose the problem, I took it to the dealer two weeks ago.  Initially they pulled the codes and said it needed a fuel purge valve and oil restrictor valve (94810425001) on bank 1.  The parts took three business days to arrive.  After installing them, the codes indicated the restictor valve was bad on bank 2-another couple of days.  After they changed the fuel purge valve and the oil restriction valves (94810425001)on both sides the idle was still rough.  

 

At that point they called to inform me they did not know the problem and needed to call the Porsche Techline for assistance.  The factory guys said the hydraulic valve (94810530803) at the back of the head needed replaced-that needed ordered too.  Guess they know their stuff, the truck runs great now, but it took the dealer 11 business days to repair my truck.  

 

 

 

 

 

 

[Doug_B_928]

Glad they got it figured out and thanks very much for posting this information.

[ekstroemtj]

Did you had to pay for all the work they did without solving your problem?

 

[Ddavidoff]

Loren - I have a similar issue. Any details on how to replace 948-105-308-03?


Sent from my iPhone using Tapatalk

[Loren]

6 hours ago, Ddavidoff said:

Loren - I have a similar issue. Any details on how to replace 948-105-308-03?


Sent from my iPhone using Tapatalk

 

Similar still might not be the same issue. Are your fault codes the same as the original posters'?

The actuator valve just held in with a torx screw I think. Don't forget a new 0-ring (999-701-582-40).

 

 

 

 

[Ddavidoff]

No codes that I know of. No CEL. Just rough idle / lower than normal.


Sent from my iPhone using Tapatalk

[ma77hewsu11ivan]

Thank you for sharing this. Having intermittent rough idle. No CEL. For that at least. Yet...


2009 Cayenne S

[Loren]

Most rough idles are caused by a dirty throttle body not letting the correct amount of air through the idle holes near the butterfly. I would always start with cleaning the throttle body.

If that does not fix or improve the idle I think you need to start looking for air or vacuum leaks in both the intake and exhaust systems.

[ma77hewsu11ivan]

Most rough idles are caused by a dirty throttle body not letting the correct amount of air through the idle holes near the butterfly. I would always start with cleaning the throttle body.
If that does not fix or improve the idle I think you need to start looking for air or vacuum leaks in both the intake and exhaust systems.

Thank you Loren. Cleaned the throttle body. Seemed to make a moderate difference at idle and smoother acceleration. Pretty sure I also have an exhaust leak as I'm noticing sooty water drippings on my garage floor, front passenger area... And keep throwing P0421/31 codes. Cats replaced last year. Mind sharing the voltage range for front and rear O2 sensors? I easily found the rear sensor output with my Durametric. Not sure I'm finding the fronts? Would 1.9v make sense up front? Rears bounce between .6-.1v. Thank you in advance, Matt in Chicago - 2009 Cayenne S w/142k miles. (Next project is fluids for brakes, diff's, transfer case and tyranny :)


2009 Cayenne S

[Renzo511]

2004 Porsche Cayenne S  8 cylinder

140k miles.

 

Fair amount of oil in my breather hose running from AOS to throttle body (I believe it's called the crankshaft breather hose )

 

Could this be causing my #8 cylinder to misfire and foul plug ?

 

Is my AOS bad or is something else causing this oil in the hose ?

 

 

[lewisweller]

5 minutes ago, Renzo511 said:

2004 Porsche Cayenne S  8 cylinder

140k miles.

 

Fair amount of oil in my breather hose running from AOS to throttle body (I believe it's called the crankshaft breather hose )

 

Could this be causing my #8 cylinder to misfire and foul plug ?

 

Is my AOS bad or is something else causing this oil in the hose ?

 

 

Most likely yes. 

http://www.pelicanparts.com/techarticles/Porsche-Cayenne/67-ENGINE-Repairing_the_Air-Oil_Separator/67-ENGINE-Repairing_the_Air-Oil_Separator.htm

 

You can buy the membrane for 30 dollars from

https://vanos-bmw.com/membrane-94810513107-porsche-cayenne-45l-450ps

 

As for the misfire it's more likely a coil issue try swapping the coil from 7 to 8 and clean both plugs and see what happens, if 8 is OK and 7 is now fouling then you know the coil is the issue. More unlikeky is the no' 8 injector (dripping/blocked) or piston rings worn or cylinder scored or a valve not closing and not sealing properly. 

[Renzo511]

New coils just put in 1700 miles ago.

 

Just Pulled plugs  today which I put in same time I did coils.. #8 was black with crusty black deposits on it ,. Assume oil.

That's why I am thinking AOS is bad.

 

No real smoke at exhaust other than normal start up on cold day. No blue smoke and using around 1 quart of oil per 600-700 miles which I believe is normal.

 

Thank you for your help.

[lewisweller]

8 hours ago, Renzo511 said:

New coils just put in 1700 miles ago.

 

Just Pulled plugs  today which I put in same time I did coils.. #8 was black with crusty black deposits on it ,. Assume oil.

That's why I am thinking AOS is bad.

 

No real smoke at exhaust other than normal start up on cold day. No blue smoke and using around 1 quart of oil per 600-700 miles which I believe is normal.

 

Thank you for your help.

Doesn't make sense to me that the aos would foul only one plug on one cylinder. I think this cylinder 8 is scored. Only way to check is to bore scope it and do compression test and leak down test. Maybe valve stem oil seal is leaking pass the valve but less likely. 

Well documented issue with the S, is the  cylinder lining coating defect. 

 

Could try a thicker oil to reduce the oil quantity escaping passed the piston rings but its really not a solution. Rebuild is expensive and some owners just run it until it's dead. 

 

Some pictures is always helpful!

[Renzo511]

Compression tests done...All in good range.170 153.

 

Still have a lot of oil in crankcase breather hose.

 

Inspected diaphragm in AOS and there are no cracks ,splits or holes...Cleaned it all up.

 

Checked for vacuum leaks...None noticed , Even sprayed with CRC

 

What can cause this oil in breather hose.. I noticed it's dirty around AOS and also where hoses go into to valve covers on each side .

 

Engine is running rich and some smoke for few minutes after start up. Smoke is white and not coolant smell.. smells of fuel and just a strong stinks exhaust. 

 

Plugs were pretty black and seem to be carbon as they were dry but had an oil smell... 

 

I am so darn confused her now...

 

What is the air flow direction between the AOS and and throttle body ( this is where the crankcase breather hose with the oil in it is..)

 

Any help would be appreciated.

 

 

[lewisweller]

1 hour ago, Renzo511 said:

Compression tests done...All in good range.170 153.

 

Still have a lot of oil in crankcase breather hose.

 

Inspected diaphragm in AOS and there are no cracks ,splits or holes...Cleaned it all up.

 

Checked for vacuum leaks...None noticed , Even sprayed with CRC

 

What can cause this oil in breather hose.. I noticed it's dirty around AOS and also where hoses go into to valve covers on each side .

 

Engine is running rich and some smoke for few minutes after start up. Smoke is white and not coolant smell.. smells of fuel and just a strong stinks exhaust. 

 

Plugs were pretty black and seem to be carbon as they were dry but had an oil smell... 

 

I am so darn confused her now...

 

What is the air flow direction between the AOS and and throttle body ( this is where the crankcase breather hose with the oil in it is..)

 

Any help would be appreciated.

 

 

Again some pictures would be great!

 

Have you tried new plugs and run for some km then plug and check to gauge the extent of the problem and how the start up white smoke is affected? 

 

The dirty oily parts around connectors is bad or old oring on the fittings just leaking a bit of vacuum in. 

 

How much oil are we talking about in these pipes, pictures pls

[Renzo511]

I put new plugs in today.. still running rich.

 

I will get pictures in morning.

 

If I pull the crankcase breather hose off and let it drain for a few minutes there is a puddle the size of a quarter.

 

I'm assuming this oil getting by is fouling my plugs.

 

What else could be causing oil to appear in this hose ? Or is the only option a failing AOS diaphragm and cap

[paulwu]

On 1/21/2017 at 8:58 PM, Renzo511 said:

Compression tests done...All in good range.170 153.

 

Still have a lot of oil in crankcase breather hose.

 

Inspected diaphragm in AOS and there are no cracks ,splits or holes...Cleaned it all up.

 

Checked for vacuum leaks...None noticed , Even sprayed with CRC

 

What can cause this oil in breather hose.. I noticed it's dirty around AOS and also where hoses go into to valve covers on each side .

 

Engine is running rich and some smoke for few minutes after start up. Smoke is white and not coolant smell.. smells of fuel and just a strong stinks exhaust. 

 

Plugs were pretty black and seem to be carbon as they were dry but had an oil smell... 

 

I am so darn confused her now...

 

What is the air flow direction between the AOS and and throttle body ( this is where the crankcase breather hose with the oil in it is..)

 

Any help would be appreciated.

 

 

Have you fixed the issue at the end? I have exactly the same symptom as you had, going crazy and find no cure!

 

Thanks,

[Rick150]

Excess fuel, Mass air flow sensor dirty, engine temperature sensor faulty, dirty air filters, oxygen sensor faulty. Then go on to check fuel pressure and related items.

 

All engines have blow by and it would be expected the blow by gas will be rich in UN-burnt fuel and oil mist in your case.

 

The AOS will have oil around it including the hose, so when the crankcase has a little pressure then the valve will work sending the oil rich gas to the intake to be burnt ( causing carbon build up on intake valve stems, but that's another story). Look at how the engine knows the correct fuelling, one of those inputs to the ECU is giving the wrong information, I have mentioned a few, find it!