redridge

sounds like you may have a bad coil pack cylinder 5. I would just replace them all if you havent done a tune up lately.

mglobe

I agree with this advice.

Ahsai

+1 on coil pack #5 assuming you meant they only switched out spark plug #5 but not coil pack #5.
But if they did switch out coil pack #5 and you still have P0305, you should ask them to do a leak down test on cylinder #5.

SS911

I changed the coil packs , injections and spark plugs places...
But nothing change...
The problem is continuing...
Only i found some key words...
Firstly I add some fuel addition liquid..
So It can helps i think.Because my car gives error only one or two time...
But ı know there is a problem..
I take my car to service again..
And my car gives error 4 times..
But the 4 times is when i stay in a car and stop. Car gives error.
My engine is working but i am in D or P gear.
Actually my car is stopping but my engine is working..
Yeah my car gives the 4 times of error in this time.

and i remember the before times my car always give error when i stop but my car working.
Why it is...
I change the places of Spark plugs , injections , coil packs . But notihing change.
P0305 AND P0300 . Everytime my car say 5. cylinder problem....
Some sites i am searching.
Some people say EGT sensor or Boot caused this error.

What EGT sensor is ?Can it caused ?
Or I cant found in dictionary.What is boot ? Can it caused..
Thank you
Respect.
SS911

Macster

The engine controller is flagging a weak cylinder by storing a misfire code and turning on the check engine light.

You have eliminated sources of misfires due to spark by replacing the spark plugs and coils and even the injectors. I assume the correct plugs were used, the correct coils used, new/correct injectors, and the job was done correctly.

BTW, do you know what the plugs looked like? It would have been interesting to see what they all looked like and to see if the plug from the #5 cylinder looked different, or was a different plug, etc.

Another source of misfires is mechanical. One source can be the VarioCam system, at least on one bank (the bank #5 cylinder is on) is acting up.

A less likely source of the problem is the flywheel is damaged and the means by which the engine controller measures flywheel acceleration for each cylinder is affected and this damage is confined to just the area of the flywheel that applies to cylinder #5. However, I believe this very unlikely because I believe another cylinder would also be affected.

With the Porsche diagnostics computer the VarioCam functionality can be activiated and tested (by bank) to ensure the VarioCam system is working properly.

However, that the misfires occur only on one cylinder of one bank suggests the problem is confined to that one cylinder.

This can be due to a burned valve or a problem with one or more valve lifters at that cylinder. Another possible cause is the cylinder (or head) has a crack. This is why I would have liked to see the spark plugs that came out of each cylinder.

Anyhow, the most likely cause is something mechanical at cylinder #5.

Now a compression test of the engine is I think called for. But check with your trusted mechanic to get his opinion.

Sincerely,

Macster.

petman74

Hello. Please.I have the same problem on my C2. I have vibration on the motor and fail on the 5th cylinder.
Did you found any solution?
Thanks much Petr

Macster

More details would be nice: miles on the car/engine; did the symptoms appear after the car sat a long while; after the car was washed, left out in the rain; was in the shop? Is the engine stock? How about the gasoline in gas tank?

Generally, for a misfire you start by eliminating the usual sources of misfires. These are the coils and plugs, unless the misfires can be explained by for instance the engine have been recently treated to a wash that gets it all wet which can have the thing misfiring its brains out.

In your car's case though with just one cylinder misfiring unlikely the symptom can be explained by a bit of moisture.

But even before you replace anything one course of action is to clear the codes and then drive the car to see if the codes come back.

However, with the engine running rough this may be uncomfortable for you to do. And depending upon the reason for the misfires it may not be the best thing to do or it could even be the wrong thing to do.

Have you removed the oil filter housing -- use a *clean* drain pan -- and looked at the oil and at the oil filter element for any scary sign of metal bits?

Sincerely,

Macster.

petman74

Hello. OK, so. I bought this car 1 year ago like crashed.
During this time (completly rebuilding to 997 look) the car sat without the running. Motor is 3,4 liter.
Now I changed the oil filter, oil, airfilter and plugs. Gasoline is shell V power racing - 100 octane and our Benzina 98 octane.
After deleting the code they are coming back.
In the oil was not any metal element but i have to change the RMS seal, because there is oil leak !
thanks Petr.

logray

Here is a link to the misfire troubleshooting guide:

http://www.renntech.org/forums/index...ttach_id=24613

I would pull the #5 spark plug and see what it looks like compared to a good cylinder.

Could be a bad pack, bad plug, stuck lifter, bad injector, bad wiring, or other cylinder problem (slipped sleeve, cracked sleeve, etc.).

C4CRNA

Is the gas old?

petman74

No. I have filled only fresh 98 octane or 100 octane gas.

Pac996

1. Inspect and clean MAF. Make sure wiring is good to it. Location is on tube between air filter box and intake of engine. Only use approved MAF cleaners. Do not touch the metal or move it.

I think cleaning the MAF first is a good idea since it gives the computer data it uses for how much gas the injectors put out. I started thinking this when I tried finding an online trouble shooter for both of your problems. I found "A failing mass air flow sensor or EVAP purge valve can cause misfire issues.". I am with both of you that tearing the engine down is the wrong answer to try first. Anyway my thinking is cylinder 5 is picked for the error code when it is eaither the weakest or when the system can't pick any certain cylinder for being the offender. I don't think there is an error code for dirty or irregular reading from MAF.

Hopefully there is spray cleaners available for the MAF cleaning in your countrys. Be sure not to handle the metal or move it. The plates are very sensitive. Touching them harms the plates ability to detect how much air is going to the engine. This is how the computer rates the amount of gas to inject for the proper fuel mixture besides the O2 sensors. If you had bad gas mileage before the rough running engine symptoms the MAF being bad or dirty is very possible. Even replacing the MAF is cheaper than the first hour of labor.

http://repairpal.com/misfire-due-to-...urge-valve-303

petman74

Hello. At first I changed the wiring. Now it looks good.
I will check it within a few running if the error will not return back in CU.
Thanks a lot for helps to all.

petman74

I add a picture of my frozen car C2 996 modified to GT3 997.

logray

Looks great!

And hopefully your misfire problem is solved.