Doug_B_928

The attached pdf is a write-up from my recent variable valve lifter solenoid replacement. It's a newbie-rated, detailed, pic-intensive write-up. This is a simple task but, due to a number of factors identified in the write-up, it can be difficult and at times frustrating. If I were to do it again I'd probably use the intake manifold removal method. But, in case anyone is curious, this pdf details how I did it.

koister2001

Thanks much for your effort putting this together. My 2008 GTS has an error code 1372 (valve control lift, bank 1, implausible signal) and I will replace the solenoid to see if it will clear the code.

Doug_B_928

Glad to hear that you're finding it useful. Do you have a rough idle along with the code? You'll find that I documented every detail and, with the cautions I highlighted, there shouldn't be any surprises. Let us know how the replacement goes and hopefully it solves the problem.

koister2001

Hi Doug, mine (actually my wife's) does idle just fine. If it had any roughness in the idle, it might be insignificant to my ears at least for now. I just have an error code when I scanned with my Durametric and wanted to clear it as a part of routine maintenance.

You seemed to have clear the code, but do you still have a rough idle? Rough idling can occur for various reasons, but at least you have cleared one of many. Hope you had a success with the rough idling by now.

Doug_B_928

The rough idle persists. It's at the dealer for diagnosis and they are a bit stumped as well. The codes came back so they are thinking one or more stuck lifters but they really aren't sure. They said they've never seen lifters stick/fail on the 4.8. According to them changing the valve lift solenoid has always taken care of it. The only good news is it's not scored cylinders. Their compression tests found 270 psi on all 8 cylinders.

deilenberger

Unless Canadian PSI are different from US PSI - that's AWFULLY high for compression. Like REALLY REALLY high. Sure it wasn't 170 PSI?

Doug_B_928

I know, it surprised me the first time I read the specs and when I told the service manager at the dealership what I had found on my own compression test he didn't believe me. According do the documentation I have, the naturally aspirated 4.8 has a 12.1:1 compression ratio with an expected pressure range of approximately 18 to 25 bar (261-363 psi). The maximum allowable difference between cylinders is 3 bar (43.5 psi).

tripnut

I have exactly the same code as you P1355. You say that changing the Variable Timing Solenoid didn't work for you and I think it will be the same for me because I only get the code for cylinder three and if the solenoid was faulty I would expect it to work all four cylinders as there is only one and it's on the end of the bank.

What was the final solution to fixing code P1355? I would appreciate the FINAL SOLUTION (not in a German way).

Best regards.

Paul.

Doug_B_928

In my case it was leaking injectors. When scoping the cylinders the dealership noticed the injectors were leaking and they contacted their 'higher-ups' to see if that could be the problem. The 'higher-ups' didn't know but suggested to try it to see (a very expensive 'hail mary'). But, thankfully, it worked and the car has been running great ever since.

tripnut

Doug, This is a huge help because I also get the code for a dead coil so if it was injectors for you and it could be that changing the #3 coil will clear it for me. It looks like the code is a fairly ambiguous "something wrong with a certain cylinder" and not specifically the valve lift solenoid or it could be that if anything goes wrong with a cylinder it knocks the valve lift mech out of whack.

Nice 928 in your photo, yours? I had one in 1990's and it's still the nicest driving car I ever had. Smooth and handles similar to an old XJ6 but even better handling, power and ride. A real continent crosser I had lots of problems with the heating / air conditioning on mine and it was way before the internet, Porsche dealers were very unhelpful and wouldn't give out any information. I finally sold it on when the head gasket went.

Doug_B_928

Yes, it does seem to be an ambiguous code. Hopefully in your case simply changing the coil will solve it. I'd swap coils on left and right banks and see if the code changes.

Yes, that's my 79 928. It's my favorite car. Rennlist has become an indispensable asset for help with maintaining all of these older Porsches. If you still had it you'd surely find some help on the 928 subforum to straighten out any issues.

Good luck and let us know how it goes resolving the issue.

tripnut

OK here is an interesting little story:

I got the computer out last night and put the race kit ignition timing into the ECU of my R1 race bike to see if I could release the whole 200 RW BHP and decided to pick up the new coil on the bike. When I got to the dealer and he gave me the coil in the huge box I took the coil out of the box to shove it down my jacket, the salesman then gave me a lecture about how delicate the coils are so I unwrapped the coil from it's bubble wrap to take a look. The coil looked a bit like it had been fitted and cleaned up so I insisted he gave me a new clean one without the dirt. He begrudgingly left the counter and came back with another which didn't have bubble wrap and was just packed into a plastic bag inside the box.

It's obvious that the first coil that I was offered was old and they probably know the dead coil code also brings up other codes so. I believe this was an old coil that someone in the store had swapped it out.

I have just fitted the coil and got most of the same codes after starting up, I then cleared the codes and lo and behold the car now runs as smooth as a baby's bottom and codes don't return.

Here are all the original codes the new coil has fixed:

P0353
P2308
P1355
P0303
P2181

Lot of codes for just one coil!

Pbacon

I had the error code 1372 left bank implausible signal on and off for the past 80K miles. Replaced the position sensor. Helped for about 5 k miles then came back. I could reset with Durametric and the CEL would stay off for several hundred miles then illuminate again. After a long drive, about 200 miles more or less, the light would turn off. Nothing in the codes either, then after driving around town, it would illuminate again. Have been chasing all sorts of fixes.

The idle recently started getting a little rough at start up but I did not really notice it. At the suggestion of Les at Docs Garage in Lexington, SC, we changed the coil packs and plugs. I reset the CEL again and it has stayed off for over 1,000 miles. I hope this is resolved.

i have seen several threads on this problem for most of the Cayennes of this age. I dont know why Porsche is not more helpful either. The service managers do not seem to know what to suggest other than bring it in for a dianogstic.

BTW, I bought the “new and improved” coil packs from Porsche. It would seem they know the first design is not as robust as it should have been. If you have this problem, try new coil packs. It is a lot less trouble than replacing the position sensors.

Good Luck

Vivid7

I’ve had this code show up twice in the last 3 weeks on my 08 GTS. I had another weird code for a different sensor in the intake show up a couple weeks before that. Noticed my battery was at 12.2 Volts in the accessory position. took the battery out and it was an H8. Swapped with a Bosch H9 and it no codes have come back.

Pbacon

I replaced my battery way back when this first started and it helped for a while too. I think there are several related gremlins taht tought the solenoid, battery and coil packs. Another 600 miles and the CEL is still off. Wife is happy....