droptopguy

Greetings all.

I have a 997.2 with the 9A1 engine. Base carrera, no modifications, completely stock car. 1 previous older owner who only drove the car less than 30k. Car is in pristine shape and have not had a problem with it at all in the past several months.

Recently, the car developed a bad shuttering when applying throttle coming off from a stop light. Never had any issue before this, then the engine began to misfire. Pulled codes for a misfire on Cylinder 2 (302) and "P1361" with CEL and blinking red light. Thinking that this was simply a case of old coils and plugs, I went ahead and had them replaced. Unfortunately this did not cure the issue. After a more thorough diagnostic by a dealership, I am being told that very nearly the entire top end of this vehicle requires a rebuild. Primarily based off of all new lifters and camshafts, pulling the engine and transmission and everything associated with all that. At the time the plugs and coils were replaced, the mechanic did note that the spark plug in cylinder 2 did appear starved for fuel, i.e. "not wet" compared to the others.

Now I am no mechanical expert, but I am having a very difficult time making the correlation between a single cylinder misfire and a lifter being at fault (and do all of them really need replacing even if that's the case?). The car never made a hint of noise. In fact, this is the best sounding smoothest running Porsche I've ever owned up to this point. I also haven't seen anything even remotely similar in any forum thread or technical document anywhere that I can find and I know the 9A1 is generally not an unreliable engine. My only working theory was that I've heard about how DI engines, especially early designs, have a propensity for sludging and coking of the top end due to inadequate fuel spray that typically "cleans" carbon deposits off these areas, especially in cars that are not driven hard and often.

Can anyone shed any light on what might be going on here? This is kind of a complete mystery and a huge step from a simple misfire.

platinum997

Seems extreme to me as well. Subscribed for info.

Bruce In Philly

Did the engine have over revs? Is this a manual transmission? The dealer can see this right away after hooking up the computer.

Bummer
Bruce in Philly

droptopguy

No overrevs mentioned by the dealer at all. It's a PDK. I am going to speak with the service tech tomorrow about how they came up with this approach.

platinum997

Make sure they give your a specific reason why they feel the need to open the engine up.

Check this thread out.. same issues and it was the metal strap on top of the cam cover that holds a solenoid in place that was loose. Might not be the same on a 9a1 but worth a look.

http://www.6speedonline.com/forums/9...e-light-3.html

Type_LT

I'm not expert on DI Porsche engines; however, in the VW/Audi world the symptoms of severe carbon build up show during cold start where the restricted flow can cause difficulty starting or maintaining a smooth idle (only during warmup catalytic converter initial heating). Normal carbon buildup just reduces output power and in general rough idle.

The motion of the valve keeps the part of the valve which slides through the valve guides clean, so there shouldn't be a point where the carbon builds up and restricts valve movement to the point of damaging valve train.

How does the car run after you get moving? (e.g. into 2nd gear and beyond). If it runs well after you get rolling, all the way to near-redline, then I'd be suspicious of the diagnosis.

There are other things such as the variocam actuator and fuel delivery to that cylinder that could be an issue. I think variocam issues might show misfires in the entire bank so that's a slight chance it's the problem.

andy92782

How many miles are on this car/engine? 30K-ish?

My previous car was a BMW 335i (N54 engine). Those were notorious for carbon build-up on the intake valves due to DI. The symptoms my car exhibited showed up when the engine was under heavy load / heavy acceleration: the engine would stumble and hesitate. No other issues - it idled smoothly. I had the intake valves media blasted clean and after that everything was good, but I didn't have to do this until over 60K miles.

One problem I had with it was due to a bad fuel injector. It was leaking fuel into the cylinder after the engine shut off and it kept fouling that spark plug. The symptom was hard starting and stumbling before it idled. Your car seems to have the opposite issue - maybe not enough fuel?

Seems like an awfully huge diagnosis. I'd take the car elsewhere for a second opinion.

droptopguy

Wow this such a great community. I almost never get replies this thorough as a newb in most other forums.

to answer some of the questions... under 30k... the car tends to run notably rough right from startup. Never stalls but there is a notable "wop-wop-wop" to the idle and when cold you can even faintly see that pattern of that running in the exhaust puffs of the evaporating condensation. Once you take off it is semi rough until 45 mph or so at which point it really starts bucking against you. The PDK seems to really get confused by all this.

And again, this was the smoothest running car on the planet a couple of weeks ago. It was fine when we went to dinner, and did this on the way home. The only environmental change was that it was right after the last snap of VERY cold weather in south Texas. Perhaps a day or so later.

I agree about the variocam. That sounded like a promising lead until my old mechanic where I used to live said that would not likely be throwing codes for one cylinder but rather a bank for that side.

DC911S

bad gas perhaps? Did you fill up after a rain? Water can get into underground tanks. Bad gas can cause all kinds of problems

semicycler

So misfire on cylinder 2, all coils and plugs swapped, and mechanic notes the plug on cylinder 2 looks off. Your description of the running engine at idle and at speed sounds like you are running on 5 out of 6 cylinders.

Google searching Porsche specific OBDII codes yields this:

P0302 - Misfire, cylinder-selective (#2)
P1361 - 911 Carrera Valve lift control, cylinder 2

P1361 is a big clue. Everything is pointing to a problem in cylinder 2 only, probably lifter related, either mechanical or electrical. So start with the control circuit first, perhaps changing the lifter solenoid on that cylinder and inspecting the wiring. Then move on to tearing into the cylinder head on that side to go after a mechanical lifter failure.

edit: looks like on the 997.1 at least the lifter solenoid is for each bank controlling 3 cylinders each. Not sure if the 997.2 is the same.

droptopguy

This is correct. For some reason when I tried to search out that P1361 code on google I was getting all KINDS of weird results for other brand vehicles. I never found the lifter control failure code description.

So after talking with the tech today, no disassemby was done at all. Based entirely on the P1361 and the computer telling him the car failed the lifter control test they came up with the diagnosis of changing all the lifters/cam followers and everything that entails. Technician stated that in his experience with previous 997s (mostly M96/7 cars but he said this would be the third 9A1) that that particular scenario indicates a failed lifter with dirt somewhere in the system. Should clarify too that camshafts were never part of it, I couldn't read his writing too well. It was "cam followers".He also stated that an oil change and Zmax treatment might be enough to get it worked loose.

In any case, 13 grand is just not happening. The car will be headed to my old out of town euro mechanic next week for more thorough diagnostics. I'll probably eat these words later but I just can't see a mechanical lifter failure at such low mileage on such a well maintained car. It makes no sense. If it IS the lifter, I'm gonna have the one offending cylinder fixed and then get rid of the car. I hate to be so scorched earth but I'm never gonna trust the car after that again. By contrast I had a 2008 Turbo that I was ALWAYS concerned something major was going to fail on because it was a higher mileage unit at 68k. The ONLY problem I ever had with it was the all too common coolant fitting failure on the top side of the engine for which it had to go back twice and never was fixed right. But it wasn't catastrophic, and that car had been through 6 (!!) owners before me. NOT babied at all. Go figure.

Bruce In Philly

I feel for ya,

After having two engine failures in my 2000 Boxster S, I carry that worry every time I start up my '09 C2S now with 105K miles. M '09 has been fairly solid... had leaking rear shocks that were probably the most expensive repair item.. but the engine has been rock solid.... except for its odd ticking and other goofy noises. Oil consumption is about 1 quart every 5K miles.

I just have not found a car or brand that is more fun. Although this 911 is not as fun to drive as my Boxster S was... they have softened up these cars too much. But that is just me.

Peace
Bruce in Philly

Macster

One or more cylinder can manifest a misfire that can be traced, with the proper diagnostic tests, to the failure of the low to high lift (or high lift to low lift) feature of one or more intake lifters.

Porsche blames this on "dirt". The "fix" is to replace all the intake lifters of the bank even if only one cylinder is manfesting the misfires.

While I have come across a few of these cases at various times I have never heard of the camshafts being replaced.

I don't have the factory manual for your car but I have one for the 996 Turbo and this manual has a section that covers trouble shooting misfires. If you want, private email me a suitable email address and I'll respond with a PDF of the section of the Turbo manual that deals with this, that documents the steps necessary to properly diagnose this.

While some brands of DFI engines appear to develop engine deposits and it was suspected at the intro of the Porsche DFI engine it would manifest this problem -- this was the techs talking to me after they returned from training on the new DFI engine -- the word I get is the Porsche DFI engine doesn't develop engine deposits.

But just in case... However, I have to preface what I'm about to suggest with this: If the engine is running poorly you probably don't want to drive the car but if the engine is running ok -- but triggering a misfire error code once in a while -- you could try a bottle of Techron. (Techron Complete Fuel System Cleaner, in a mostly black bottle.) Use according to directions. Well, the bottles I buy on the label indicates the bottle treats 20 gallons of fuel but I just dump the entire bottle into the fuel tank of my car which holds just under 17 gallons of fuel.

The general rule is if one notices any improvement from the engine to when the fuel with the Techron added gets low, low enough to refill the fuel tank, to dump in a 2nd bottle. I would modify this to just repeat the treatment regardless if there is any benefit noticed from the first bottle. After this 2nd tank of fuel is almost gone to then change the oil/filter, as the Techron can add to the engine oil's contamination.

SnP

Definitely get a second opinion

I was getting trans failure and feared I needed new pdk. My indy diagnosed a cracked coil that was sending an error form the engine computer to the trans computer and sending the pdk into shutdown.

The software in these cars is complex and a small error in one place can lead to big problems in other places.

SnP

Would also mention my car ran rough until I replaced the high pressure fuel pump. Wasn't getting a dash light but it was throwing codes (don't know what they were.) There was a shop campaign at one point on them.