MK19

Here's what I wrote many months back.....and then below, and update:
Advice from the board indicated coils and or plugs which sounded very reasonable.

So, now to the present;
I replaed coils on #4 and #6 (most frequently showing up along with code 0300) and I swapped coil #5 with #1 just to isolate it in case it was bad. I also put in 6 new plugs. RESULT: Exact same CEL's and same codes within 15 miles. Checked several times clearing in between. I'd had zero effect and now believe it is something else.....but WHAT??[/INDENT]UPDATE - And here's the Update and apparent cause/solution:

After many posts, lots of help from the board and especially from Kevin (thanks all), and numerous steps inbetween including smoke/leak test the induction system, Code 1155 possible "flat tappet", examine cam angle operation and many other inputs and outputs to the ECU with a Porsche tester etc., I finally turned it over to a reputable local shop who does a lot of Turbo work; he had the car for 4-5 weeks driving and testing and driving (I'm sure it was sitting a lot too). In the end he says he traced it to one of the two vario cam solenoid control valves that are on each side.....the horizontal one on the passenger side for that bank #2 where the problem was. The PET calls this a "throttle control element valve", p/n 996-105-301-71.

I can see from wrench marks that the rear engine mounts were removed presumably to lower the engine to gain access to this valve.....although it is not clear that the cam cover was removed. It's not obvious to me that this valve, located between the rear most two spark plugs, is accessable like a spark plug or if it is under the cam cover. I don't recall seeing it there when changing plugs.

In any event, I paid him $1k and the problem is indeed gone. It does sill seem to s i cry tlight load, steady speed of 3000 RPM. But no codes are recording and no CEL.

So I hope this helps one of you sometime. And thanks agian for all of the help.

Also, if anyone has had a similar experience or has knowledge of the function of thes valves.....please chime in.

Thanks all. MK19

Chuck Jones

.....It does sill seem to s i cry tlight load, steady speed of 3000 RPM. But no codes are recording and no CEL..."

Would you please explain that last sentence....I'm interested in your issue for future reference.

Wachuko

+1... this is one for the archives... Thank you!!

manny_g

here it goes....i think he is saying that the car still seems to miss under light loads..." if my interpretation is incorrect, i'm sorry.

MK19

You are right....."it still seems to miss under light loads at ~3000 RPM"......sorry for the ham handed typing.
M

MK19

Any other experience out there with this failure of the "throttle control element valve" and effect on cam control?

Thanks,
MK

manny_g

i've heard that these v.c. solenoid control valves can be the culprit for many issues in these cars. an additional symptom of a defective s.c.v is erratic idleing.

Bos

This is a real stretch, but I'll toss it out there for consideration. I had a very similar issue with my former C4S and misfires on one bank. Many hours chasing codes, replacing sensors, checking valves, replacing parts, etc. and it ended up being a melted aftermarket cat.

John D II

I had a similar issue that was suspected to be the cam solenoids. CEL at steady, light throttle (P300, 301,302,303, I think) - never under hard throttle. I tried everything you did except the cam job, then a fellow board member that had the same problem and had the cam solenoid job done for 2K, without fixing the problem contacted me. He ended up finding a broken tappet solenoid bracket. A $20.00 part fixed his problem. I checked and found a broken tappet solenoid bracket, but it was on the wrong side. On a chance, I purchased a new tappet solenoid for the problem side (same codes as you have) and a new bracket for the broken side and now it's been 1 season without the CEL that plagued me daily for 2-3 years and nobody could find it. My car ran perfectly with the bad tappet solenoid, so it was not a big deal, just annoying - it would go off if I took a cell phone call and started cruising easy and steady (about 3000 RPM's) - never when giving it gas. In fact, if I saw the CEL begin to flash, I could give it gas quickly and it would go away, but if I stayed at part, light throttle, it would register. I would still be driving with that CEL had the person not PMed me with his experience and I remain very greatful for that....

Wachuko

Any chance you kept record of the part numbers... I would like to see where these are located... is it an engine out ordeal to inspect and replace? Thanks.

John D II

Wachuko,

I do not have the part number, but it is very inexpensive and easy to replace. It is like doing spark plugs. If you are doing plugs, it's right there between a couple of coil packs. The bracket has two small screws and once the bracket is removed, it pulls right out. Insert the new one, resecure it and your done. A little oil will seep out, but that's it. This little part caused me many hours of wondering "what the heck my problem that nobody could diagnose was..."

If you have my same symptoms and can't find the fix, it's worth the $125 part cost to try this.

Regards,

John

Zippy

I fixed P0300, P0301, PO305 etc on a couple of occasions by replacing injectors.

kilrgt

The bracket that holds the variocam solenoids are a known issue with these cars. I found this out by talking to a very good Indy the one time i took the car in for a oil change there. In fact he had them in stock and changed them for me.They were cheap and didn't charge much for labor.
Thanks for posting your updated info.

Wachuko

John,

My car does not have those symptoms. But if this is common enough in our cars I want to have a spare set of those brackets. Porsche has this tendency of raising the prices on parts as the cars get older...

What I do have, but no error codes, is a bit of a, not sure how to describe it, hesitation, cutout, something around 3K rpm that I have always tought was due to the variocam... I reported it to the dealer but they did not find anything. I should have driven the car with them to show them exactly what it was. Almost as if I was lifthing the pedal just a bit and then pressing it again... that type of shudder...

riley6

I'm glad I found this post, I am having the same problem - misfire codes on 4, 5, & 6 at 3000 rpm with light throttle. Did anyone here also get a valve lifter codes?

Two different shops changed plugs, switched around coils and O2 sensors, did leak tests, etc...to no avail. I was worried I may have to get Variocam work = expensive. So I'm going to show this post to the shop, to see if the bracket solves it. Worse case is this CEL issue something you can live with, without further damage? If I can't fix it cheaply, I'd rather invest that money in mods.