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Wyowolf - thank you, I appreciate you taking the time to comment!
For anyone else interested, I'll post an update when I figure out the issue.
Hey if you find out what it is that helps everyone else as well... I have a 12S so I always read these threads incase something is amiss I can hopefully narrow it down quickly...
I am assuming you are aware of the variocam bolts failing on this engine and have checked none of these have sheared off? You can inspect from the oil filler with small mirror on the side of the adjuster facing the windscreen.
There is also a very interesting troubleshooting video on Youtube where a mechanic does a bunch of testing on the variable lift solenoids at back of motor. It is an hour or so long and very informative. Symptom was misfire from memory.
My VIN wasn't subject to the variocam bolt recall, and I did check and verify I had the non-dimpled bolts when I was in there - pretty sure it's not the variocam, at least as far as bolts are concerned. Should maybe look to see if there are other failure types.
When the lift solenoid (bank of engine) failed on bank 1 it was VERY different to what I'm experiencing now on bank 2 - which is why I guessed, wrongly, that it was the timing solenoid under the valve cover. I'll look for the video you mention; with these things it's usually a different perspective that gives you the light-bulb moment.
i have a small camera and looked trough the oil cap into the engine where tou can inspect the upper part of the U guide (between the V). If you se that the plastic is missing on the guide that you know what to do…
Originally Posted by Dave_997
Thanks guys, that would be bad…. Is there a way of inspecting/confirming that doesn’t require the timing cover to be removed? I didn’t see any evidence of broken plastic under the valve cover and the fact that this happened suddenly would suggest a major failure if it were the guides. Would I not see some broken plastic transported up by the chain?
Thx! I did exactly that and the u-guide (at least the top of it) is still in place. With the timing deviations I'm seeing I don't think it's timing related. I'm now wondering if it could be bearing related. There are not many documented 958 V8 failures, but there are at least a couple with spun bearings. Considering next steps....I think it's beyond my ability to diagnose at this point.
with both banks generating the same fault codes, a few questions:
- Have you had ALL the fault codes read with a PIWIS or similar scanner? If so, please share them and then did you clear all of the fault codes?
- Was there ANY maintenance performed prior to the faults?.
- How long between the last refueling and the faults?
- Have you checked related fuses? there are a number of engine related fuses spread across 3 fuse boxes , e.g. #11 in the engine compartment fuse box.
Hi CAVU - really appreciated your DIY on the solenoid replacement! The fact there were codes for both banks gave me pause as well.....
I don't have access to a PIWIS level scanner. Codes were read using both Durametric and iCarSoft, and were consistent between them. It is possible that some/all of the codes were stored prior to the car starting to run rough, but given the nature of the codes and the symptoms, something related to the VVT made sense - at least back when I started investigating. Later, after I had then been 'playing' with connectors and had replaced both of the bank 2 VVT solenoids I cleared all just to be sure. They did not come back in the time I let the engine run afterwards ~5 minutes - not sure if they should have, or if it could possibly take longer. It's not driveable and I'm hestitant to even let it run/idle at this point.
There was no maintenance performed immediately prior to the fault occuring. Most recent was replacing the transfer case fluid in Febuary (which, if anyone is interested, appears to have cured what I had thought was another pending failure - the first box was replaced around 50k I believe), prior to that it was an oil change about 3 months/2k miles ago, and a problem with the transfer case module connector in Jan 2022; can't believe these could be related.
I can't remember exactly when I filled up with gas, but it would have been within the week prior to the issue arising, possible as recent as a day prior.
I checked the VVT fuse, and then the remainder of the fuses in the engine fuse box. I did not go through the interior fuses but that's something I will do now that you've mentioned it.
My VIN wasn't subject to the variocam bolt recall, and I did check and verify I had the non-dimpled bolts when I was in there - pretty sure it's not the variocam, at least as far as bolts are concerned. Should maybe look to see if there are other failure types.
When the lift solenoid (bank of engine) failed on bank 1 it was VERY different to what I'm experiencing now on bank 2 - which is why I guessed, wrongly, that it was the timing solenoid under the valve cover. I'll look for the video you mention; with these things it's usually a different perspective that gives you the light-bulb moment.
Dave if your variocam bolts do not have the centre ‘security’ pin/round then you are good. Easy to check. The link above is worth watching, it is slow but very informative and may or may not be useful.
I came across that video too - turned out it was the lift solenoid on the back of bank 1 on his car. It took him an hour and I felt bad watching because I could have told him what it was straight away! Exactly how mine behaved when it failed. Funny that it was also a 2012 meteor grey CS like mine.
I think I’m going to drain the oil tomorrow, it’s the one thing I haven’t done. If there’s damage to the internals I assume I’ll see some metal flakes in the oil or filter.
Was no metal in oil filter so I finally had it towed to the dealer.
Good new and bad news. Good news is car is fine, bad news is I’m an idiot. Turns out that when all of the bolts holding the cat to the exhaust pipe fail completely you get all of the symptoms above. I was so focused on the engine - where the sound seemed to be coming from - that I missed this. With the car on a lift I’m sure it would have been more apparent. This was on the driver side. There was only one of three bolts left on the passenger side so it seems this failure is just a matter of time in the north east.
Appreciate everyone’s help, and sorry to have so bodged the diagnosis. I did, however, learn a lot about the engine in the process - and replaced some perfectly good parts for the next owner. Maybe this post will save someone else the heartache.
...Turns out that when all of the bolts holding the cat to the exhaust pipe fail completely you get all of the symptoms above. I was so focused on the engine - where the sound seemed to be coming from - that I missed this. ...There was only one of three bolts left on the passenger side so it seems this failure is just a matter of time in the north east.
Thanks for closing this one out.
I certainly think you are in contention for the annual "never heard of that one before on a cayenne" award.
03-29-2023, 08:01 PM
