Assistance with diagnostic trouble codes

[Doug_B_928]

My wife's 2008 Cayenne S has had a very slight and somewhat intermittent vibration at idle for the past few weeks.  Last weekend I hooked up my durametric.  There were no trouble codes.  I didn't see any significant number of misfires.  I looked at the set point for the HPFP and the actual value and they were very similar, suggesting the HPFP is fine. 

I took a 250 mile round trip yesterday-today and today, at the beginning of the return trip the check engine light came on (solid, not flashing).  The car runs fine but when I got home I tried revving it and it won't rev above 4K RPM (I'm guessing this is 'limp mode').  So, I pulled out my durametric and checked for faults.  There were faults in 3 modules as follows:

 

1. In the Engine module there were 4 faults:

(a) 0131

O2 sensor circuit low voltage bank 1 sensor 1

value below lower limit value

(b) 1355

Valve lift control, cylinder 3

Implausible signal

(c) 0301

Lost communication with gear shift module

Value below lower limit value

(d) 44FA

 

2. In the Air Conditioning Module

(a) 819

Air-conditioning pressure sensor

Open circuit/short circuit to ground

 

3. In the Automatic Tailgate module

(a) 3234

Function restrict. due to critical vehicle electric. system condition

 

Here is the work log which should be able to be opened with the durametric software

Work Log-2016-12-16_04-50-20-PM.htm

 

I clear the faults and short tested, and the only one that remained is #3 (Tailgate module). 

 

I've been wondering if my battery is in need of replacement.  Would the low voltage to the O2 sensor create a rough idle?  And, would that be a problem with the battery or a bad sensor itself?  The Valve lift control sounds scary, but it's just an implausible signal so I'm guessing that's also electrical.

 

Loren and other gurus, what do you figure?

 

[Loren]

If the battery is over 4 years old I would replace it to start.

Clear the codes again and re-test with a new battery.

[lewisweller]

Yep battery is first on the list. 

12.6volts engine off ignition off, 13.5-14.2volts engine running at idle and at any rpm the voltage should remain stable (or the alternator rectifier is faulty).

Anything less than this is going to cause problems. Ask me how I know!

[Doug_B_928]

It's over 14 volts and steady when running, but I tested it with ignition off using a multimeter a couple of hours after returning from my trip and it measured 12.17 volts.  

 

I'll get a new battery tomorrow and report back.

[lewisweller]

12 hours ago, Doug_B_928 said:

It's over 14 volts and steady when running, but I tested it with ignition off using a multimeter a couple of hours after returning from my trip and it measured 12.17 volts.  

 

I'll get a new battery tomorrow and report back.

Weak. 

[Doug_B_928]

Purchased and installed a new battery today (got the same Varta from the VW dealer).  The one in it was original, with 25/7 stamped on the ground post (I think the truck was built in July of 07; 9.5 years is pretty impressive).  Cleared any faults, took it for a 20 minute ride, checked for faults and none found.  But, the idle is unchanged.  At idle, in Park, the set point calls for 580 and the actual idle fluctuates between 576 and 544, if I remember correctly.  It's at the former more than the latter and the change back and forth is quite quick.  This is a very minor vibration that you can perceive only in the seat of your pants, so to speak.  I had the coils out in September (for a bi-annual check up) and they looked fine.  I replaced the plugs 4 years ago and they have gone 50,000 kms/30,000 miles; should still be fine. I could take out the plugs and clean them to see if that helps.  Should I try cleaning the MAF?  Or, should I just leave well enough alone (I suspect the dealership would say that this minor vibration is normal)?

[lewisweller]

1 hour ago, Doug_B_928 said:

Purchased and installed a new battery today (got the same Varta from the VW dealer).  The one in it was original, with 25/7 stamped on the ground post (I think the truck was built in July of 07; 9.5 years is pretty impressive).  Cleared any faults, took it for a 20 minute ride, checked for faults and none found.  But, the idle is unchanged.  At idle, in Park, the set point calls for 580 and the actual idle fluctuates between 576 and 544, if I remember correctly.  It's at the former more than the latter and the change back and forth is quite quick.  This is a very minor vibration that you can perceive only in the seat of your pants, so to speak.  I had the coils out in September (for a bi-annual check up) and they looked fine.  I replaced the plugs 4 years ago and they have gone 50,000 kms/30,000 miles; should still be fine. I could take out the plugs and clean them to see if that helps.  Should I try cleaning the MAF?  Or, should I just leave well enough alone (I suspect the dealership would say that this minor vibration is normal)?

I would have a good look around all the vacuum and pcv hoses for cracks or minor issues, oil cap, dip stick, AOS, change the plugs (check the coils anyway) and remove and clean the throttle body carefully and the maf sensors. Reassemble everything clear codes and then finally do a throttle body alignment. 

 

Start car and let idle for at least 5mins. Go for a long drive with various cruising speeds and full Throttle bursts to redline. 

Check codes and idle speed will probably be spot on. 

The age would suggest engine mounts will be tired and transmit some vibration to the cabin via the chassis. 

[Doug_B_928]

Update:  I'm still having the idle issue.  I removed and cleaned the throttle body.  No improvement.  Apparently this car has 'hot film' sensors that are not cleanable; at least that's what I read somewhere on the 'interwebs'.  Not sure how to 'align' the throttle body.  I tried removing the cap on the AOS but it really feels like I'm going to break it.  I've seen the Pelican write-up and it looks simple, but it really does feel like it will break before it stretches enough to go over more than one tab at a time.  I checked the vacuum at the T by the vacuum pump and got a steady -75psi.  Does the fact that it's steady suggest that it's not a vacuum issue?  I checked the coils and did find the one on cylinder 7 to be cracked.  So, I replaced it but the rough idle persists.  I checked codes last week and there were some bizarre ones, but they all cleared.  Just checked again this morning and the only one that's back is:

 

1355 Valve Lift Control, cylinder 3, implausible signal

 

I'd rather not replace all of the plugs and other 7 coils ($$$) without knowing that it will solve the problem.  Does anyone know what this problem points to?  Could it be carbon build up on the valves?  Camshaft position sensor?  Are there any 'actual values' I can look at to get/provide more data?

[Doug_B_928]

I think what I've taken pics of below are the camshaft position sensors.  The right bank's sensor has a lot of oil residue around it.  I looked with a mirror and it doesn't appear to be coming from anywhere else.  The sensor appears to be in tight, though I didn't try to tighten it further.  Does the oil residue around it indicated not only some kind of seal issue but also a potential problem with the sensor?  Should I try removing it, cleaning it with a lint free shop towel, and seeing if that makes a difference to the idle?  Or, should I switch it with the other side to see if I start getting a trouble code on the left bank?

[deilenberger]

I suspect the oil on the sensor is a non-issue and is probably just a tiny bit of seepage around the seal for it.

 

You got some good advice - but can't see that you really followed up on it. You seem to have lost wrenching interest with the coils.. :-)

 

LESSON: If one coil has crapped out - the other ones are just sitting there thinking about crapping out. They are all the same age and operate in the same environment for the same amount of time. DO all the coils.

 

It was suggested you start checking for hose leaks. I'll describe a method I've used in the past - but am not suggesting you do since I don't know your skill level and you might destroy life as we know it. It involved using something flammable to try to find intake leaks. It should be done OUTDOORS with a really good fire extinguisher handy, with proper eye protection and clothing that won't go up in a puff of smoke.  I usually use some flammable carb cleaner - some people use an unlit propane torch. The carb cleaner has the advantage of being quite accurate since I spray it using the red-plastic tube that comes with the can (and when I can't find the tube - it's in the darkest corner of my garage - spiders seem to take them to build nests or something.)

 

I use the spray giving TINY little spritz's of it around any suspected leak points while the engine is idling. ANY (and I'll say it again **ANY**)  change in idle means there is a leak where you just sprayed.  I'm very careful not to spray on things like the exhaust system, or anything else that might ignite the carb cleaner.  In this case - I'd be spraying around the multitude of corrugated plastic pipes that run around the engine, the throttle-body, and the MAF sensors.

 

FWIW - the MAF sensors can be cleaned. They usually don't need to be - but if someone ever used an oil-cloth/foam air filter on the vehicle they quite likely would need cleaning. Hike down to your friendly local auto parts place and look for "CRC MAF Cleaner" - you remove the MAF, and spray the part sticking into the airstream. It's a flat hot-film sensor. Let it dry completely before reinstalling it. There are two of them on your S..

 

I'm trying to remember what triggers a throttle-body relearn - but I believe it's done when you switch on the ignition and then simply press the gas pedal to the floor without the engine running. You may have to do it 3 times, but I think not. You're just teaching the ECU the travel/vs/resistance reading of the gas pedal and syncing that to the two check-sensors on the throttle body.

 

The top engine mount is also suspect (as was suggested to you.) Use a MAGLITE and look very carefully at the rubber bushings. ANY sign of cracking of the bushings means it's toast and should be replaced.  There is also the possibility the lower mounts are sagged - but they're a lot harder to check and on some models (the turbo for sure, not sure on the S) the engine has to be dropped, or the suspension subframe dropped in order to replace them. Bad mounts will allow engine vibration to travel into the vehicle.

 

As far as the "1355 Valve Lift Control, cylinder 3, implausible signal" error - does it tell you if it's presently active? Or how many times it's been captured?  I'm not sure how that measurement would be detected - on "cylinder 3" - since the camshaft sensor is on the back end of the camshaft. I suspect it may be looking at the firing time vs the camshaft position for cylinder 3, meaning a bad coil might well give that error message. I'm sure some Porsche tech could tell you.

 

Good luck - let us know how it works out for you.

[Doug_B_928]

Thanks, Don, for taking the time to look at the info and respond.  No loss of interest, just a combination of lack of time and trying to be penny-wise.  I visually inspected everything for cracks and put my mityvac on the tester port by the vacuum pump.  Figured I'd need a smoker to test better but your carb cleaner idea is an interesting one.  If I attempt that I'll wait until it's nice enough outside and will have my wife watching with fire extinguisher in hand :) .  Good to know hot film MAFs can actually be cleaned.  Air filters in it have always been factory or OEM.  I'm aware that coils tend to go at the same time, but inspect them frequently enough that I figured I'd try to save the $ and replace as each one goes out, but it has been in the back of my mind that one or more other coils could still be causing this.  The  engine strut mount looked good when I did the coils, but I'll inspect it more closely.  Haven't checked the motor mounts as I have to wait to get it up in the air.  I did the throttle body adaptation re-learn a few times, with no improvement.  The 1355 code doesn't provide any additional information.  From what I can tell, all I can do is clear it and see if it comes back (which is what happened).  The CEL does not appear with this code, at least not yet. 

[lewisweller]

2 hours ago, Doug_B_928 said:

Thanks, Don, for taking the time to look at the info and respond.  No loss of interest, just a combination of lack of time and trying to be penny-wise.  I visually inspected everything for cracks and put my mityvac on the tester port by the vacuum pump.  Figured I'd need a smoker to test better but your carb cleaner idea is an interesting one.  If I attempt that I'll wait until it's nice enough outside and will have my wife watching with fire extinguisher in hand :) .  Good to know hot film MAFs can actually be cleaned.  Air filters in it have always been factory or OEM.  I'm aware that coils tend to go at the same time, but inspect them frequently enough that I figured I'd try to save the $ and replace as each one goes out, but it has been in the back of my mind that one or more other coils could still be causing this.  The  engine strut mount looked good when I did the coils, but I'll inspect it more closely.  Haven't checked the motor mounts as I have to wait to get it up in the air.  I did the throttle body adaptation re-learn a few times, with no improvement.  The 1355 code doesn't provide any additional information.  From what I can tell, all I can do is clear it and see if it comes back (which is what happened).  The CEL does not appear with this code, at least not yet. 

If I remember correctly the possibles for this for other people's fixes was:

1. Coil (swap the new coil from 7 to cylinder 3 and clear codes, its free and a quick check you need to drive a while to be sure though not just around the block, maybe a day or two with a few starts at least 300km). 

 

2. Vacuum leak for sure can somehow cause cylinder 3 to also be the magical problem cylinder on the v8. Don't ask me why but it is.

 

3. One member had this code and turned out to be the hydraulic valve lifter (inlet or exhaust not sure) was getting stuck. He had all his lifters replaced as a matter of course and problem solved.  I don't know who or how it was diagnosed. I don't see how the dme can tell individual cylinder has the issue that accurately, it must be combination of knock and crankshaft sensing as it fires plus lambda signal for that precise time and it cleverly combines the data to work out what the issue is and where. 

 

I don't see the harm in removing the sensor(s) cleaning checking swapping unless when you remove they break, then not so penny wise. Lol. 

 

What i would do for a trouble code ........

 

 

[Doug_B_928]

Thanks very much Lewis.  I hope it's not #3.  I will test per the suggestions.  

[Doug_B_928]

Update:  So I sprayed carb cleaner to hunt for vacuum leaks and did not find any (doesn't mean there aren't any as I was a bit nervous about the fire hazard and so may not have been as thorough as I could have).  I checked the engine stabilizer bar and the rubber looks fine.   I also switched coils between cylinders 3 and 7, cleared the fault, and after a bit of driving the fault came back on cylinder 3.  There is another thread on this list (something like 'Cayenne S Rough Idle Resolved') where the problem turned out to be the variable valve lift hydraulic valve.  His codes were not the same as mine (he had an overall code and a similar code on two cylinders on the same bank), so I can't be sure that's the problem here.  I looked at actual values in my Durametric.  There are some values for the variable valve lift.  I forget the nomenclature, but there appears to be a setpoint beyond which the value for a given cylinder is rough.  I watched this value for all of the cylinders at idle and it looked like 3 was often at/near the setpoint and sometimes a bit above it.  So, based on Lewis' input above I guess it could be a sticking lifter on cylinder 3.  I think, unless anyone out there has a better idea of what this trouble code means, that I'll soon have to take the car to the stealership so that they can at least diagnose it. 

[lewisweller]

49 minutes ago, Doug_B_928 said:

Update:  So I sprayed carb cleaner to hunt for vacuum leaks and did not find any (doesn't mean there aren't any as I was a bit nervous about the fire hazard and so may not have been as thorough as I could have).  I checked the engine stabilizer bar and the rubber looks fine.   I also switched coils between cylinders 3 and 7, cleared the fault, and after a bit of driving the fault came back on cylinder 3.  There is another thread on this list (something like 'Cayenne S Rough Idle Resolved') where the problem turned out to be the variable valve lift hydraulic valve.  His codes were not the same as mine (he had an overall code and a similar code on two cylinders on the same bank), so I can't be sure that's the problem here.  I looked at actual values in my Durametric.  There are some values for the variable valve lift.  I forget the nomenclature, but there appears to be a setpoint beyond which the value for a given cylinder is rough.  I watched this value for all of the cylinders at idle and it looked like 3 was often at/near the setpoint and sometimes a bit above it.  So, based on Lewis' input above I guess it could be a sticking lifter on cylinder 3.  I think, unless anyone out there has a better idea of what this trouble code means, that I'll soon have to take the car to the stealership so that they can at least diagnose it. 

Well I reckon the inlet valve lifter on cylinder 3 is getting stuck hence the low o2 voltage code, remember an o2 sensor can only see oxygen or lack of it and it can't see the unburnt fuel that is likely being dumped and not fully combusting due to lack of air. Your engine year has variocam plus which is inlet cam advance of 25 degrees and valve lift height adjustment from 3mm at idle to 10mm at higher rpm I think roughly. Which sequence is not functioning properly I don't know. But its all pressure oil flow controlled. 

For me two options

1. take to garage and brace yourself for some possibly wallet bashing news.

Or

2. Take a really long shot chance and engine flush it with mobile 1 engine flush fluid and hope that it can flush out the sticking or stuck valve lifter component. It may be waste of money gamble but if it works may save you 1,000's dollar in engine tear down repair. 

This procedure is drain very hot oil and fill with 8-9 litres of mobile flushing fluid (don't use a flush additive because it's cheaper its not as effective) start and let idle for 8mins (check this duration according the spec) and then drain fully, replace filter (check old oil and the filter for debris which may indicate internal issues) and add new 0w/40 mobile 1 fully synthetic oil 9 litres odd.  

Follow mobile 1 flush instructions and do this at your own risk some people swear engine flush is bad news, personally I think that is crap, maybe on a total old and sludgy POS engine a flush will dislodge gunge that may get trap somewhere unwanted and also make gaskets that where caked and plugged start leaking etc.

I have flushed my golf R 2.0t at 10,000km intervals with mobile 1 and refilled with mobile 1 0w/40 for 3 yrs running 21psi boost 350bhp and the new owner still has it purring like a kitten at 150,000km, he brought it to my warehouse just the other day in fact to adjust the APR tune selection back to 98ron setting via the cruise control stalk which he managed to fumble into valet mode lol. Did a quick vagcom scan for him and everything was spot on. 

 

Good luck and keep us posted how you get on. 

[Doug_B_928]

Thanks, Lewis.  I'll look into the M1 Engine Flush.  But I should clarify that the only code that is occurring is the 1355 (the others in my first post in this thread have not come back since changing the battery).  Not sure if that affects your thoughts on the cause but I just thought I should make that clear given that you implicate the O2 sensor voltage code in leaning toward the sticking valve lifter.

[lewisweller]

5 hours ago, Doug_B_928 said:

Thanks, Lewis.  I'll look into the M1 Engine Flush.  But I should clarify that the only code that is occurring is the 1355 (the others in my first post in this thread have not come back since changing the battery).  Not sure if that affects your thoughts on the cause but I just thought I should make that clear given that you implicate the O2 sensor voltage code in leaning toward the sticking valve lifter.

Yes your probably right the code would be bank 1 system lean or exceeds limits or something, being as it was low voltage it's the sensor power supply side or one of these ghost codes that bad batteries produce to totally mislead you.  

[Doug_B_928]

Update:  I took the car to the dealer and, as suspected, they diagnosed the trouble code as the valve lifter solenoid.  They said replacing it has always solved the problem in the past.  So I spent last weekend doing the replacement.  I have a write-up forthcoming on that.  Unfortunately, the rough idle persists.  So even the pros are a bit confused by this one.  I'll probably order new plugs soon and, if that doesn't work, then bite the bullet ($$$) and replace the remaining 7 original coils. 

[lewisweller]

2 hours ago, Doug_B_928 said:

Update:  I took the car to the dealer and, as suspected, they diagnosed the trouble code as the valve lifter solenoid.  They said replacing it has always solved the problem in the past.  So I spent last weekend doing the replacement.  I have a write-up forthcoming on that.  Unfortunately, the rough idle persists.  So even the pros are a bit confused by this one.  I'll probably order new plugs soon and, if that doesn't work, then bite the bullet ($$$) and replace the remaining 7 original coils. 

Ummm this sounds familiar! The guy that changed the valve lifter also had the solenoid diagnosed first and replaced without success. 

If your near your oil service maybe worth doing the flush and oil change? Gamble vs possible engine tear down.....

[Doug_B_928]

Where do you get M1 flushing fluid? 

[lewisweller]

7 hours ago, Doug_B_928 said:

Where do you get M1 flushing fluid? 

I'm checking now and for the life of me I can't find it. The last time I used it was when the Mobil 1 service centre in dubai did the 110,000km oil change on the Golf about two years ago. Maybe it's been discontinued? Alternatives are liqui moly which has the best reviews, for an add to old oil type flush. 

[Doug_B_928]

Thanks for checking, Lewis.  When I was at the dealer for diagnosis I did ask them about a stuck lifter.  They were fairly adamant that a stuck lifter would be causing a CEL.  Do you recall who the fellow was with the stuck lifter?  I'd like to PM him to see if he recalls a CEL or any codes he was getting.

[lewisweller]

59 minutes ago, Doug_B_928 said:

Thanks for checking, Lewis.  When I was at the dealer for diagnosis I did ask them about a stuck lifter.  They were fairly adamant that a stuck lifter would be causing a CEL.  Do you recall who the fellow was with the stuck lifter?  I'd like to PM him to see if he recalls a CEL or any codes he was getting.

This is it. My mistake he didn't change the solenoid in fact. 

Amazing he only had 50k odd on the engine as well. 

Edited April 3, 2017 by lewisweller

[Doug_B_928]

Thanks, Lewis.  He did a great job of detailing his problem.  I'm not getting misfire codes and his symptoms are a bit different (his alternating between what appeared to be the lifter getting stuck in high and low positions).  I'll talk to the dealer about it again this week when I'm there picking up the cowl end cap that I broke (cheap plastic crap) when taking it off to do the solenoid.  It makes sense to me that my lifter on cylinder 3 could be stuck in the high lift position, so not switching to low lift below 1400 RPM.  But, the code is intermittent and when I watch the 'lifter roughness' on the cylinders it tends to fluctuate, though cylinder 3 is usually around the set point for lifter roughness (7). 

[Doug_B_928]

Update:  I took the car to the dealer a week and a half ago.  It had finally thrown a CEL and valve lift codes had returned along with a couple of misfire codes.  They were a bit bewildered.  They did find two injectors leaking and want me to authorize 8 new injectors.  They said there is a TSB on the injectors.  I'm wondering why change them all if only two are leaking.  Their technical advisor is saying that the leaking fuel injectors could cause the valve lift fault, but they can't be sure.