silotwo

I know that the dealer did mine with the engine in the car, the tech did lower it somewhat. He did tell me that Porsche says to remove the engine, but he had done this bank before with the engine in. I would assume that saves some $$.

Targan

I will talk to the mechanic tomorrow and try to find out what his approach would be. Would definitely talk to him about compression test first.
I ve bought ton of stuff from Sunset. Will give them a call and find out cost of parts as well.
I will keep you all posted on the progress. Thanks again for your help and support.

Macster

imho compression test unnecessary. The fact the DME is logging misfire error codes (at least for cyl. 6) is telling that cylinder is suspect, most likely it is weak.

At this point I'd consider a leak down test to try to determine why the cylinder is weak.

I do not think it is a bad valve lifter.

What I suspect is it is a burned valve. But it could be something more serious.

Sincerely,

Macster.

dcdrechsel

Macster -don't know how you can jump to your conclusion so quickly .I believe that all the computer is registering is that cylinder 6 isn't working correctly .Generally a compression test will indicate whether the cylinder can sustain combustion .The leakdown test is a good tool for isolating to rings or valves .
I don't have the manuals for Variocam plus but in old variocam world the protocol is test the injector -coil-and then replace the lifters .

Macster

The cylinder has already been flagged as not working correctly.

While the engine is running the DME constantly measures the output of each cylinder by measuring the acceleration imparted to the flywheel by the cylinder's power stroke.

If this acceleration is below (or above) a low (or high) threshold a misfire error code is logged and the CEL is turned on.

In short, with the CEL on and error code P0306 logged, the DME has already signaled there's a weak (or overly strong) cylinder: #6.

The issue now is why is the cylinder weak. (I am going on the assumption the cylinder is unlikely to be that much stronger than the other normal cylinders.)

A compression test at this time is redundant.

A leak down test can help identify the reason the cylinder is weak.

Off the top of my head I would offer the opinion that at this juncture about all a leak down test will tell one is if the problem might be addressable with the engine left in the car or if the engine has to be removed.

In short does the problem lie with #6 cylinder's valve hardware: Is a valve leaking?

Or is # 6 flagged because due to a problem with its piston/rings/cylinder: Is the piston/rings/cylinder unable to develop/sustain healthy compression pressure?

If the OP wants some other method of confirmation the suspected cylinder is weak and worth investigating further there is this: The tech with the proper diagnostics/test computer while the engine is idling can turn off each cylinder's spark and fuel. The effect in engine rpm/idle speed is noted. If a cylinder is weak it is contributing less than the other cylinders to the engine's total output and the idle speed/rpm will drop less when the bad cylinder is disabled.

The VarioCam system can be tested as well. Off the top of my head I can't recall the test procedure -- it varies depending upon whether the engine is fitted with VarioCam (intake timing control only) or VarioCam Plus (intake valve timing and lift control) -- but it is spelled out in the engine's factory OBD manual.

Sincerely,

Macster.

dcdrechsel

You left one part out -if the valves aren't opening correctly it probably won't fire correctly .

Targan

Macster, dcdrechsel,

A little more info. Leak test has been completed and the mech said at this point he is positive it is the sticky lifter. I will forward your points on to him though (just to get him to read what you all are thinking). He said compression test was not done but he said that would d redundant and would not give him any different conclusion.

Work will be done with the engine in the car. Decided to do just one bank. He his willing to get it done even if I buy my own parts. Got a quote from Sunset and Pelican. Buying everything from Sunset except Intake valve lifters (which I am getting from Pelican parts for half of Sunset's price). Total cost - $758 for parts for one bank.

I will post mechanic's email response to your thoughts once he gets back to me.

Thanks again!

dcdrechsel

Sounds good and looks like it should be a sucessful fix !

Steven C.

Been here done all of this..... First go around was a bad exhaust lifter maybe 30,000 miles ago. So we replaced all of them on the right side. Then last Summer same issues as you are having. Did everything you have done and finally bit the bullet and said go into it(no need to drop the motor either time). Well this time it was not only a bad intake lifter on #6 but a broken cam!!!!!! Yes, right under one of the journals the darn thing was broke in half! Fell out in two pieces. So this time a new intake cam and all new lifters. Saved the motor most probably and lucky as I was pissed about the whole deal and drove the car for 10,000 miles with the problem. Car has 103,000 miles now and runs fine.

From my research 99.9% of bad lifters are on the right side and codes always relate to #6?

Macster

No need to post the mechanic's email response. If he says the cause of the engine's behavior/symptoms it is X he's at the car, he's at the engine. I couldn't disagree with him and have any firm ground to stand on.

All that matters is if you believe him then do what he says will fix the problem.

From the Porsche factory manuals I have access say to when a bad lifter is suspect all lifters of that type on that bank are replaced. I do not know the thinking behind this other than if one lifter is bad the others being of that same 'batch' are suspect too and replacing all is done to ensure another one of the original of a possibly bad batch of lifters doesn't go bad a short time after the bad one was replaced.

My recollection is the cost in lifter hardware is not that much extra compared to the cost of labor in getting access to the bad lifter and replacing just that one.

Be sure you save all the old lifters and if you want see if you can id the bad one.

Sincerely,

Macster.

dennis hiip

Targan, Keep us informed on the progress. Thanks

Dharn55

I know it is possible to remove the cam cover and the cams to change lifters wit the engine in the car, but based on my experience I think it would take less time to drop the engine. Although many shops charge more I can drop the engine from my car (and it is a C4 so some extra steps) in my driveway, on jack stands laying on a roller creeper in about 3 hours.

Steven C.

Absolutely no reason to drop the motor. Plenty of room. If the book says to drop the motor they were smoking something that day.

Targan

Okay, this is getting more interesting. I put my car in the garrage while I waited for my parts to arrive from sunset. Two days ago, I pulled the car out of the garrage to wash and detail (good way to spend time with her when she is not running perfect :P ).

Started the car, pulled it out of the garrage and had no CE light or mos-firing. I put the car on idle and waited and still had no CEL.

Washed and waxed, then decided to go for a drive to see how long it takes before the CEL is back. 20-25 minutes of driving later, still no light and the car seemed to running perfect with no Mia-firing on all 6 cylinders. Parts came in yesterday and I drove the car to work again and it is still driving perfect.

Dilemma now is, do I wait for a while and see if I have any issues?

Or

Like the mechanic said, may be the lifters get sticky only when the engine gets hot. P.S: Just a couple of weeks ago, I drive the car 250 miles and had no issues but the next morning CEL was on. It was 60 degrees outside. There really has been no consistent pattern. So, should I go ahead and get the lifters fixed anyway?

Let me know what you all think.

LRBill

Madison isn't very far from Milwaukee..... Does Nitrorocket work on Porsche's?