oatmealadam

58k miles. oil changed every 3-5k. bad luck or just Porsche engineers with a flawed design to pump out production numbers.

Ended up being a sticky lifter. Decided, proactively, just to replace all the lifters. Smooth and fantastic running once again.

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.

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 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.

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.

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 ...

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 ...

What exactly did you finally do to fix the issue? Sent from my SM-G930W8 using Tapatalk

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.

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.

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 2nd and 3rd 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.

I understand this post is a bit dated now, but I have recently had the same code (P1372) thrown on my 2008 Cayenne GTS. I ran the code with my VAG-COM as it was able to read several control modules I never knew it could do. Anyway, the vehicle has 89,XXX KM and ran fine until I came off an aggressive highway drive to a stop. MIL came on, idle was rough, but achieved same fuel mileage and felt same power. I cleared the MIL and it stayed off for a couple of days. I found that only when I drove aggressively the MIL would come on after several drives. If I drove it easy or the wife drove it, no MIL until eventually I got back to driving it a bit agressive. I changed on plugs and coils, as it was due anyway. Sprayed MAF cleaner on sensors, checked hard plastic vent tubes on front and rear of engine valve covers. Front had small crack that I repaired. Sprayed intake valve cleaner directly into throttle body, as well as removed throttle body to clean thoroughly. .... still have check engine light, BUT the rough idle is gone and it only seems to idle a bit lower than normal from how I recall. When I was at the Porsche dealer discussing with the part personnel he mentioned a common failure are the camshaft valve actuators/solenoids that are within the valve covers on the backside of the engine banks. Part number he gave me was 94810530405. He explained it as not being able to engage variocam and causing power loss, rough idle, etc. Anyway, it seems this may be the problem. What I want to know is if anyone knows specifically HOW to test this electronic actuator? They cost about $300+ each, plus valve cover gaskets. I am mechanically inclined and intend to do the job myself, but I don't want to start replacing expensive components without a way to test their function first. Any input is appreciated and if I do the job I will follow up to confirm the fix or not. The P1372 code seems odd, as I thought if the actuator did fail or were stuck somehow it would have its own specific code for it, whereas P1372 valve lift control is generic??? Also, worth mention, I reside in Ontario and it's not frigindly cold, but has been about 25F to 60F during the day. The oil I used was LubroMoly 5w40 A40 spec for Porsche. I heard some people discuss using a thinner 0w40 oil as this can cause the actuator to stick??? I changed the oil and filter 4,000km ago now. Please help.

Where in Canada are you located? If you're in Ontario and not far from Hamilton, try Raz Automotive Service. He has a reasonable labour charge, experience with Porsche (and other German cars), and able to rebuild from bottom up rather than replace.

P0430 TWC Conversion, Bank 2 - Above Limit Possible fault cause: - Oxygen sensor ahead of and after TWC exchanged - Valve lift fault - Aged oxygen sensor after TWC - TWC faulty I would reset this and if it comes back check and or replace the O2 sensor (likely if the car has 60k miles or more). HVAC Fault code 31 Voltage too low or Voltage too high Not uncommon if the battery has been changed or disconnected. I would reset this also. Cluster 9121 Oil pressure - Failure of oil pressure indicator Possible cause of fault: - Sensor for oil pressure indicator faulty - Short circuit to voltage/ground or open circuit in the wiring between the sensor for oil pressure indicator and instrument cluster ABS/PSM Fault code 4460 Pressure sensor Possible cause of fault: - Short circuit to ground/B+ or open circuit - Plug connection on stop light switch faulty - Incorrect adjustment of the stop light switch - Wiring/plug connection between pressure sensor and control module faulty - Pressure sensor faulty Thanks for the detailed answer. My battery was weak when I bought the car, so I put a new Optima battery in it. Then, before I stored it for the winter, I took the optima and used it for my other vehicle and I put the battery that came with the Porsche back in it. However, I also use the Porsche battery tender over the winter and the battery is much stronger now and always reads 13-14V when the engine is running after starting it. The car has 74,000 kilometers, so maybe it's the O2 sensor. It's only come on after storage, but rarely when it's driven on a regular basis ... so likely nothing big, I hope. I replaced the brake switch under the pedal and have not had the code return yet. It typically throws the code in city driving where I am driving low speed with frequent slow stops. Never on the highway, this year, has it done it, but last year I had it on the highway and it threw the code and the brake lights never came on. But that's not the case this time. Oil pressure only happens on cold mornings, but when the car is warm, never again. I will replace the sensor and see if that fixes it. Anyway, I appreciate all your input and explanation. Much easier than getting straight forward answers from Porsche.