2008 Cayenne GTS MIND BOGGLING ENGINE LIGHT ... BEGGING FOR HELP

[oatmealadam]

I am praying anyone with some expert knowledge or past experience can help me with my valve lift control fault codes and misfires all on bank 1. Please see the 5 attached pictures from my Durametric. Vehicle is a 2008 Cayenne GTS with 90,000 kilometers. 4.8L V8, automatic.

Several months ago I got a CEL coming off the highway from about 135kmh to a stop. At that moment the CEL illuminated and the idle became rough and felt too low. Get home with full power and code only shows valve lift control fault on bank 1. Read through forums and common fixes … thus far I have replaced several parts as I will briefly elaborate below:

 

All 8 coil packs & plugs, valve lift control solenoids on both banks, cleaned MAF’s, changed air filters, all 8 fuel injectors, cleaned backside of intake valves, cleaned air intake and throttle body (re-calibrated throttle position), disconnected battery for hard reset of modules to re-learn, swapped camshaft position sensors between banks. I swapped coils/plugs as well to see if the problem would follow, but it only affects bank 1. Valve lift control solenoids and fuel injectors are the newest part revisions.

 

I did a compression test, leak down, and borescope. I had a master Porsche mechanic at an independent shop verify my numbers are all similar and within reason. Nothing out of the ordinary. One strange after effect from cleaning the intake and after swapping injectors for new ones was the rough idle was at that time much smoother and stable, BUT when I took it for a drive at about 3500 RPM it felt like the engine was being held back and the RPM’s wouldn’t increase as rapidly as it did when the idle was rough. So it was evidenced to have smoother low end idle, but almost like a loss in top end power … maybe variocam wasn’t active??? After the engine cooled overnight and I drove it the next day the rough idle returned, BUT I once again had rapid RPM increase at higher RPM and full top end power … the exact opposite of the day before. This phenomenon was replicated three times. The first time was after spraying CRC intake valve cleaner into the running engine. The second time was after doing the compression and leak down tests (plugs removed of course and turning clockwise at the crank). Third time as mentioned above. However, after each time it’s the same scenario, let the engine cool overnight and rough idle as usual next day with full top end power. This is how it is at the moment.

 

I have read forums for hours, visited a Porsche Premier dealership, and been to a master Porsche tech shop. The dealer wasn’t too investigative for my liking and their diagnostics are very expensive. The independent shop is thinking it may be a timing issue and wants to reset timing. My Durametric pictures show the cylinder banks are off by about 6 degrees compared to one another. The indy also recommended the fuel injectors judging by the fuel trim values, which are in all honesty a bit better now because they were double digits previously.

 

SORRY THIS IS SO LONG, BUT BELOW IS THE POINT OF MY POST NOW.

I have the fault codes shown in my attachments. The software incompatibility with transmission control module fault is a new strange one that only came up after the 2^nd and 3^rd time of having top end power loss with MAF fault codes … like it was suffocating for more air, but shifted rough in anticipation of a rapid RPM climb. At the moment the transmission is both auto and manual sport shifts fine.

 

When idling rough, cylinder #3 misfires constantly. In a span of several seconds it has misfired in the double digits. HOWEVER, as soon as I drive, whether easy or hard acceleration, the misfires are gone. The misfires only return when nearing a stop (<10kmh) or when stopped at idle in park or drive. My fuel economy is still giving me about 500km out of a 90L fill up … so I think that’s typical.

 

Being that I have replaced some common parts for this problem here is my theory I hope someone with in depth knowledge can confirm may hold true or is completely off and impossible. Perhaps rare, but is it plausible coming down from a high speed run off the highway that my timing chain could have jumped a tooth or teeth? Is 6 degrees variance between camshafts tolerable? How many degrees is 1 tooth on a cam gear? Being the chain is 1 piece, the tensioner is only on bank 1 side, is it possible the tensioner has failed and allowed slack on bank 1 to jump a tooth and change timing? Is it possible the chain is stretched at 90,000km?

 

I bought the timing tool kit and have a rough idea of how to do it. I would turn the engine by hand after the job to ensure the valves clear the pistons. If I am unsure I will just tow it to the indy. Does anyone have a timing procedure or link to a write up for the V8?

 

I appreciate everyone’s input. I am frustrated and tired of throwing expensive parts at this problem. I am waiting for my timing tools to arrive. This is my last resort. Beyond a timing issue I am clueless. If it is timing, I am not sure why cylinder 3 is most affected. Sometimes cylinder 2 gets an occasional misfire, but nothing near as frequent as cylinder 3. The other cylinders must be firing fine, but valve control faults may be due to not seating correctly with TDC due to timing??? My thinking as that the misfire ceases at anything above idle because the timing chain now has a bit of tension applied to take up slack or advance timing? Is this why I have excellent top end power range and able to cruise along through the city without misfires until I slow or stop???

 

Thank you for your help and hopefully someone can solve this puzzle who may have gone through what I would like to believe is an extremely rare occurrence before I lose all faith in Porsche quality.

 

***If you need me to grab any live data from Durametric for pictures to verify something let me know.

[JFP in PA]

One tooth is around 12 degrees or so, so I seriously doubt you have jumped time, so put the cam timing kit on the shelf for another day.

 

That said, you are still not out of the woods as you have multiple misfires, and one bank is overly lean (#2), while the other is overly rich (#1), and a problem with the valve lift system on bank #1 not communicating; all of which would make the car run like crap.

 

I would start by looking closely at the coils and plugs on cylinders 2 and 3 to see if there is anything that would cause the misfire, like coil packs that are not fully plugged in.

 

[oatmealadam]

I have changed coils and plugs between banks thinking odd chance brand new coils were manufacturer defect, but problem remained on bank 1. Also, plugs for all cylinders, misfiring included, were of the same normal appearance. Not oily, no raw gas, not overly lean looking. The wiring themselves have been plugged on and off multiple times by me, dealer, and indy. They must be secure. One thing I am unsure of is how to check if the plug harness itself is receiving power???

 

The furl trim is much better than before, but you are right, one bank is rich and the other lean which led me yo believe the computer for DFI is compensating for a timing problem? 

 

I also thought if the variocam gear on front side of each intake camshaft, say failed in the high position, I would have lift control faults on all bank 1 cylinders and explain the rough idle, but still have top end power as usual.

[ekstroemtj]

Not necessary its the same but i had similar problems with s cayenne S and it was MAF and O2 sensors related.

 

[oatmealadam]

And did you have fault codes for the MAF and O2 sensors or similar rough idle and good top end power with codes as I have?

 

I thought about changing MF's, but at $500 each I am hesitant to dump thousands more into this unknown problem. 

 

Only twice have I had MAF fault codes and only after I cleaned intake with CRC cleaner and when I removed the intake, which smoothed out the idle, but then felt top end power was slow to climb and suffocating almost. As said in my original post, cooled overnight and drove next day with rough idle and regained top end power. MAF codes did not resurface.

 

I have cleared codes dozens of times and valveblift control bank 1 as well as cylinder 3 misfires are recurring.

[ekstroemtj]

my porsche shop was caring that time about the car. I didnt have a code reader. So i cant tell you which codes the car was showing. About what i read the MAF sensors and O2 sensors are very sensitive in case of temp. So its possible that this is your prob. I understand u dont want to throw hundreds for parts if you are not shure . Start maybe with cleaning the MAF's. Or dont buy the entire MAF.  Just change the sensors inside the housing. They trade at arround 50 USD here in Europe

[JFP in PA]

1 hour ago, oatmealadam said:

I have changed coils and plugs between banks thinking odd chance brand new coils were manufacturer defect, but problem remained on bank 1. Also, plugs for all cylinders, misfiring included, were of the same normal appearance. Not oily, no raw gas, not overly lean looking. The wiring themselves have been plugged on and off multiple times by me, dealer, and indy. They must be secure. One thing I am unsure of is how to check if the plug harness itself is receiving power???

 

The furl trim is much better than before, but you are right, one bank is rich and the other lean which led me yo believe the computer for DFI is compensating for a timing problem? 

 

I also thought if the variocam gear on front side of each intake camshaft, say failed in the high position, I would have lift control faults on all bank 1 cylinders and explain the rough idle, but still have top end power as usual.

 

For the time being, forget about having a timing problem, your own data says that you don't have one.

 

If a VarioCam unit fails, it fails in the low position.  While electronically activated by solenoid valves, it is hydraulically operated by oil pressure; so it fails low if there is no activation signal.  Your codes, however, say you are getting an implausible signal for the lift section on one bank, which usually means the lift change is not occurring.

 

If the plug harness comes loose, you have a misfire (the plug stops working).  The signal to fire the plug can also be read by voltage on the harness itself.

[lewisweller]

With multiple and possibly miss leading error codes it important to try not to follow every avenue as they may be red herrings. 

I would start with the cylinder 3 misfire, this to me is lean misfire at manifold vacuum situation, ie the manhole runner, gasket or connection to that cylinder port is leaking and drawing in extra air, this would also explain hot and cold weird conditions cos of expansion and contraction of the leak area. Also possible is injector seal for the same cylinder. 

Get the engine running from dead cold and on rough idle situation, get a spray bottle with a fine mist nozzle and start spraying water around cylinder 3 manifold runner and gasket to head and injector, if you hear the engine idle change, bingo the water sealed the leak briefly. 

At high rpm the vacuum is nil so a leak wouldn't show as much but would affect fuel trims possibly. 

[oatmealadam]

I will hold off for a couple weeks on re-timing. I ordered a smoke machine to aid in checking for a leak. I disconnected the mafs and symptoms remained so that ruled those out. Another thread mentioned the variocam vane adjusters use a diamond friction washer and sometimes at high rpm they can slip. Is this something that is possible or would i see all bank 1 cylinders with faults and misfires? I checked my battery and on cranking it dipped to 9.4v. I have heard 9.6v is the threshold so maybe my battery is the culprit? How can I check if #3 cyl is getting 12v to the coil pack... just probe it with a multimeter? Will update when I have more info ...

[bigbuzuki]

Possibly an intermittent ECU / Engine harness / connection fault.

Edited August 6, 2016 by bigbuzuki

[JFP in PA]

13 hours ago, oatmealadam said:

I will hold off for a couple weeks on re-timing. I ordered a smoke machine to aid in checking for a leak. I disconnected the mafs and symptoms remained so that ruled those out. Another thread mentioned the variocam vane adjusters use a diamond friction washer and sometimes at high rpm they can slip. Is this something that is possible or would i see all bank 1 cylinders with faults and misfires? I checked my battery and on cranking it dipped to 9.4v. I have heard 9.6v is the threshold so maybe my battery is the culprit? How can I check if #3 cyl is getting 12v to the coil pack... just probe it with a multimeter? Will update when I have more info ...

 

Take the battery to an auto parts store and have it load tested; it sounds weak.

[lewisweller]

11 hours ago, oatmealadam said:

I will hold off for a couple weeks on re-timing. I ordered a smoke machine to aid in checking for a leak. I disconnected the mafs and symptoms remained so that ruled those out. Another thread mentioned the variocam vane adjusters use a diamond friction washer and sometimes at high rpm they can slip. Is this something that is possible or would i see all bank 1 cylinders with faults and misfires? I checked my battery and on cranking it dipped to 9.4v. I have heard 9.6v is the threshold so maybe my battery is the culprit? How can I check if #3 cyl is getting 12v to the coil pack... just probe it with a multimeter? Will update when I have more info ...

You disconnected the maf and it stayed the same? Well I would have expected it would change unless the maf has something to do with the issue(s)! 

When I disconnected mine the engine bogged when revving and the idle had trouble stabilising but did settle. 

Definitely get the battery replaced these cars are renowned for electrical issues due to battery and charging problems and you could chase your *** for months unnecessarily.

The coils are negatively switched so 12vdc should be present with ignition on, on one of the pins of the connector, probe from the back with a straightened paper clip connected to red lead of multimeter and black lead on a good engine earth. 

[oatmealadam]

UPDATE - I did a load test under the bonnet and the load tester needle was on the better end of nearing "weak" indicator. So, the battery is far from terrible. Also, just for comparison I load tested my Touareg TDI the same way and got an almost identical result and my VW has no issues. I didn't have time to pull the seat back to test off the battery directly, but would my result differ straight off the battery terminals compared to the engine compartment connections?

Secondly, I tested ALL 8 plug connectors for the coil packs with the ignition turned "on". All 8 connectors gave me a 12.17V reading ... so this would mean they are getting power and have continuity. Oddly enough, with the Xenon headlamps running and ignition turned to the "on" position, after I went to start the engine I got a PSM failure flash on the instrument panel. Shut the engine off. Started again and it was gone. Is this one of those unexplainable faults as people mention with a bad battery or low voltage after I had been draining the battery while I ran diagnostics?

Lastly, I used a fog machine fitted with some tubing to direct the fog into my intake manifold. Thinking a vacuum leak may be possible. I checked all over the sides, rear, and intake area, but no smoke came out anywhere. However, I am not sure if the party fog machine has sufficient pressure to force fog out of potential leaks. Thus, I am not saying I would rule this out, but preliminary tests indicated no leaks.

I did this fog test because my misfire on cylinder 3 only occurs at idle and not driving. What I do now is drive normally, fast and slow, but when I see an unavoidable stop coming I begin to left foot brake and just as I stop I am already using my right foot to raise the RPM to around 1000RPM. Anythign over idle, even 1000RPM, stops the misfire and the engine runs smooth. ??????????????????

Can anyone tell me how to definitely rule out the variocam adjusters attached to the front of each intake camshaft? Sometimes they're referred to as vane adjuster, cam phasers ... these are mechanical gears that are fed oil from the electronic solenoids.

Lastly, does anyone know where I can get a DME re-flash? Is it a dealer only service and what would it cost? Does it need to be removed from the vehicle or can it be doen via the diagnostic plug for OBD II ?

Thanks for any input. Something is better than nothing and even something you may think is common sense or irrelevant may very well prove to be valid. Keep the replies coming ...

[oatmealadam]

On 2016-08-06 at 11:13 AM, lewisweller said:

You disconnected the maf and it stayed the same? Well I would have expected it would change unless the maf has something to do with the issue(s)! 

When I disconnected mine the engine bogged when revving and the idle had trouble stabilising but did settle. 

Definitely get the battery replaced these cars are renowned for electrical issues due to battery and charging problems and you could chase your *** for months unnecessarily.

The coils are negatively switched so 12vdc should be present with ignition on, on one of the pins of the connector, probe from the back with a straightened paper clip connected to red lead of multimeter and black lead on a good engine earth. 

 

 

Yes, when I disconnected the MAF's the engine ran the same. I drove about 30km at city and highway speeds, as well as up a steep 1.5km hill. However, I shoudl mention that I never floored it. I drove it easy and allowed the transmission to shift automatically with exception to climbing the hill where I used manual mode to drop a gear going up. Only strange thing was after about 25km my instrument cluster became solid orange around the "D" for drive and when I switched to manual mode it drove in manual mode, but the cluster still indicated the solid orange "D". As I said, it shifted fine manually or in automatic. I stopped at my destination, plugged in the MAF's, parked about 10 minutes, and drove home with no issues and my cluster went back to it's normal indicating for D1, D2, etc. or M1, M2, etc.

 

As mentioned, I checked the coils' plugs and all had 12.17V with the ignition on. Thank you for the information. I don't have any MAF codes and for the cost of new MAF's at over $1000 for the pair it's not something I want to repalce without some 99% certain method of knowing they failed. Right now, no faults or implausible signals from them so I have to assume they're fine.

 

[lewisweller]

The Maf test you did does confuse me as the engine although the dme has preset references for lack of a maf signal it should show a difference in running condition even if a little rough and jittery. Strange. 

Looking back through you lengthy repair history I'm wondering if when fixing one problem it inadvertently created another? Ie the Throttle body cleaned/manifold removed then after the gasket not sealed properly hence cylinder 3 misfire maybe? 

And sorry for me replacing the battery is the first thing I would do. $150 compared to your list of costly repairs so far is a small investment in reliability and possibly the root cause to "some" strange electrical issues ie D illumination, sensor fault codes and psm warning after some battery draining etc. 

 

Did you try misting some water or even some carb cleaner around your intake manifold and Throttle body to check for leaks? I don't think your smoker test was comprehensive especially as the Throttle is closed and likely the smoke and pressure of smoke wouldn't migrate to the manifold well. 

 

[oatmealadam]

3 hours ago, lewisweller said:

The Maf test you did does confuse me as the engine although the dme has preset references for lack of a maf signal it should show a difference in running condition even if a little rough and jittery. Strange. 

Looking back through you lengthy repair history I'm wondering if when fixing one problem it inadvertently created another? Ie the Throttle body cleaned/manifold removed then after the gasket not sealed properly hence cylinder 3 misfire maybe? 

And sorry for me replacing the battery is the first thing I would do. $150 compared to your list of costly repairs so far is a small investment in reliability and possibly the root cause to "some" strange electrical issues ie D illumination, sensor fault codes and psm warning after some battery draining etc. 

 

Did you try misting some water or even some carb cleaner around your intake manifold and Throttle body to check for leaks? I don't think your smoker test was comprehensive especially as the Throttle is closed and likely the smoke and pressure of smoke wouldn't migrate to the manifold well. 

 

 

 

Yes, I was a bit surprised how it seemed to run as usual (misfire idle, but smooth out at any RPM above idle) without the MAF's. However, while disconnected, my fuel trims were about -14% for problematic bank 1 and +3% for bank 2.

 

When I have some free time I will get at the battery in the next day or two. I will post once I know more.

 

As for the intake, these problems persisted before I ever removed the intake or ran a can of cleaner sprayed into it. I did replace all 8 intake port seals when I did remove it though. Even used light o-ring silicone to ensure a good seal and scotch brite on the mating surface.

 

I do know that after I ran the intake spray cleaner (intake NOT removed) and when I removed the intake to change injectors and clean back side of intake valves, both of these occasions I had a smooth and regular idle. It was ahile ago now and I didn't have a durametric so I don't know if it stopped misfiring, but with a smooth idle I have to assume it did NOT misfire. However, on both these occasions when I went to drive it afterward it felt like it was suffocating for more air after about 4000RPM (I think this is when variocam is active?) The RPM climb was slower. Let the car cool overnight and drive the next day ... idle's rough, but have full top end rapid RPM climb again. ???? Very strange.

 

[lewisweller]

Wow that is a brain teaser. 

 

Only related area is the intake pipe is removed for both manifold removal and to spray cleaner inside. Any possibility of a leak crack weak pipe connection???? Tried spraying carb cleaner around intake and throttle body whilst at idle??

I can't see the either of these works has any impact on the variocam. 

Also a vacuum leak wouldn't affect wot acceleration either. My brain hurts........

Thank God my audi is a dream, no breakdowns no drama. 

[oatmealadam]

Load tested battery off terminals. Indicated a good battery for a 100amp needle tester.

 

I read a post from another forum where someone mentioned when the timing chsin stretches the symptoms will affect bank 1 only and have tough idle that clears up when the engine is under load. Can anyone confirm this or refute it?

[lewisweller]

On 11 August 2016 at 6:29 AM, oatmealadam said:

Load tested battery off terminals. Indicated a good battery for a 100amp needle tester.

 

I read a post from another forum where someone mentioned when the timing chsin stretches the symptoms will affect bank 1 only and have tough idle that clears up when the engine is under load. Can anyone confirm this or refute it?

Yes I also read this info but can't find it now. 

http://www.autoatlanta.com/porsche-parts/hardparts.php?dir=9PA-03-06&section=103-15

Looking at the components is it possible your tensioning bolt item 6 is loose? Be careful it's not a case of just tightening this bolt. There is some special procedure involved and tools maybe. Sorry I don't have anymore info. 

[Jmcmilli]

I have exact same problem on an 08 S. Anything above 800 RPM and its so smooth. Below 800 RPM rough idle. I dont have all the codes observed but think it's the "valve lifter solenoid bank 1" + misfires. I'm dreading taking it to the dealer but I'm not sure my Non dealer mechanic will be able to do better.  Hoping you found the cause of this before I pay the dealer a fortune to try and figure out what must be a common issue. 

[ekstroemtj]

On 11. August 2016 at 4:29 AM, oatmealadam said:

Load tested battery off terminals. Indicated a good battery for a 100amp needle tester.

 

I read a post from another forum where someone mentioned when the timing chsin stretches the symptoms will affect bank 1 only and have tough idle that clears up when the engine is under load. Can anyone confirm this or refute it?

So how this story turned out? Could you solve the problem?

[oatmealadam]

I am still in the middle of the repair. If the repair fixes the issue I will follow up with details. Until then I don't want to lead someone in the wrong direction. Needless to say this is going to be expensive.... I hope to have this finalized in the next 1-2 weeks.

[Jmcmilli]

Any update? I've started down the same path of repairs. I've had the rough idle problem for about a month and it seemed just an annoyance until last week when after a long highway drive I had to drive for an hour in stop and go traffic. The car started to feel like it was going to explode! So bad I had it taken by flatbed to my local shop. They replaced the plugs and coil packs and tried to clean the solenoid valve but the smooth idle only lasted about a kilometer. I'm going to have the solenoid valve replaced this week. 

[Jmcmilli]

Did you get it fixed? Who did you take it to for the repair? I've been living with the same problem for months now. My local independent told me they don't have the tool required to line up the camshaft after the repair so they can't do it. Does anyone know of a good independent Porche mechanic in the Toronto, Mississauga, Oakville or Burlington area that could do this kind of repair? 

[Fmscell]

@oatmealadam did you check the crankcase vacuum, sometimes PCV valves these motors over vacuum & can cause lean misfires.

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