Check Engine Drive - P0300 - P0305 - Misfire Error - Last İnformation And Questions:(

Hi . My car 2003 996 911 CABRİOLET Carrera 4 Porsche Firstly İ have a problem.. My car suddenly start to write check drive engine problem. and when its write my car is making little a vibration. when i wait in the car. I went to porsche service they connect my car to the machine. and machine says 5. cylinder problem there is problem air and fuel mix problem.. and they say my maybe this related to my bad fuel. and they say you can continue to drive your car and you will finish your fuel. and you will buy fuel another place. maybe this cant write again. and they delete my error message. i finish my fuel and i bought new depot of fuel. and i bought some fuel addition for cleaning engine(injectors). and this didnt write again in 1 days. but after one days it write sometime. and when it write check drive engine . my car making vibration more.. but ı continue drive my car because i think maybe its related to fuel quality and it can finish. after 1 day when i waiting on the traffic lights it write again and when i want to increase my speed my car dont go fastly.. i am try to increase my speed but car dont go speedly. maybe 10 miles only. and my exhaust voice like bup bup bup bup bup bup its anormal voice. and i am afraid i restart my car. there is no problem ... but i think this isnt something important . and i drive continue my car. ı finish my depot and i bought another new fuel and some addition for engine. this error write sometimes. maybe it cant write 1 days. but when its write the vibration continue.. 2 days after i am again waiting some traffic lights. my car write the error again and making vibration. when i want to go fast. my car didnt go fast. i try to go 30 40 miles but my car is 10 miles.. and exhaust make same voice bup bup bup bup bup bup like corvette . i am afraid i restart again and my car fix. but i park my car under my home. and i am waiting. i will go to porsche service in 5 days. i realised this is serious problem. i want to ask you is there someone live this problem before. or what do you thing this is important or not . i am afraid of maybe it can make damage to my engine because there is soo expensive the engines or something. what do you think . you are the bosses about porsches problem and i want to ask you before porsche service. thank you for your replys.. good days SS911

sorry about your problem, there are SOOOO many things it "could be" and we cant hear the noises or drive the car so we all have to guess..... my advise is to have it taken to the repair shop on a trailer and get it fixed... if its running poorly and throwing lights, dont drive it.

I would try replacing the coils and spark plugs. This is a shot in the dark, but lacking any more details as to what the symtoms are, it would be my best guess. Most likely the cheapeast and easiest as well. If your problem is a misfire, this will most likely correct it. This you could do yourself.

Fuel filter. If you live in a place where bad fuel is common, then it may make sense to also replace the fuel filter ahead of schedule.

Do you have the fault code(s) from the PIWIS scan?

My Porsche tech told me that the 996 is very sensitive to bad fuel. I had problem starting mine when I filled it up at a gas station which obviously contained too much water (read condensation water). You can check my morning start problem on this video, sounded like everything was really bad but once fuel was replaced with good one, the problem never occurred again: http://www.youtube.com/watch?v=2JYgW...er_profilepage Difference with you is mine would not drive weird, the problem was only at start. Once the car would finally start, then it would drive normally.

If you believe it's a fuel problem (water in the fuel) I suggest you pick up some "Dry Gas" or the equivalent to clean up the tank of gas you have. Cleaning agents for the fuel injectors likely won't resolve water in your fuel. As Ivangene pointed out this could be caused by a whole host of different things but this is a quick easy thing to try.

The coil pack sounds plausable

Like others my best advice is to take the car to a qualified Porsche service facility and have the symptoms looked into. Could be a particularly bad dose of gas and bad enough it has fouled the fuel filter. But it could be any number of things. Be sure you insist all error codes read from the car are written down. Sometimes the error codes provide a clue as to what was going on. Sincerely, Macster.

Spark plugs and coil packs it what it sounds like except that the dealer originally said the code was bad air/fuel. if it's not the gas and not a contaminated fuel filter then maybe fuel injectors? That's not something we talk about a lot here.

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I was just wondering where Macster was. He's right of course - get the codes written down.

Thankk youu for your all suggestions... You are really interest my problem and i am happy about this. I am trying to understand your writings completely ( because my english is bad ) But ı understand 100 % 80 of your writings. Okey i will make all of these things. And i will take my car to porsche service. Thankss again..

When they read the codes make sure you write them down.... this will help diagnosing your problem.

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Wish we could be of more help. But my concern with an engine running so poorly the less the engine is run until the problem is identified and fixed the better. Even if one of us was able to come up the cause of the symptoms, almost certainly you'd still have to take the car to a professional/qualified repair tech and have the thing fixed. And he's going to want to make his own diagnosis. Which means he's going to want to run the engine. So the engine's run time when sick should be saved for this. Please let us know the outcome. BTW, how close are you to Kucukyali Is Merkezi B Block No:15 Maltepe, Istanbul? If you're ever in the area drop in and say 'hi' to Mr. Ozen at OzenElektronik from Marc @ Davis Instruments in Hayward, CA. Sincerely, Macster.

I am in Antalya but if it continue. i must to go to İstanbul for better porsche service.... F IRSTLY MY CAR gives me this error codes. P0300 - P0305 ( 5 cylinder ) ... Porsche service firstly change the spark plugs place. but 5 cylinder problem is not change. my car gives p0300 and p0305 error codes again. if the problem in spark plugs maybe it gives to us the other number of cylinder. after that services change the injection places. and if the number of cylinder change , the problem is injection. but my car gives same error code again. 5 cylinder.. so there is not problem too in injections.. and now my service want to take to pieces the my engine. because they cant found the problem now. and they want to go into engine.but i know in antalya this service dont know something. and if they go into engine . it is very bad... there is three choice --------- 1- i take my car and go to istanbul. because i believe istanbul services has more experiences 2- i take my car and i am try to fix this problem with the fuel additional something. ( i think its bullsht) I cant fix this way. and last and trustable choice 3- i ask here. i say all of the things. i give error codes and information. i think there is last chance for me . if you have suggestion to me i can give information to antalya porsche service. what do you think where is the problem .

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. code.jpg

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I agree with this advice.

+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.

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

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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.

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

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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.

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.

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.).

Is the gas old?

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

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

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.

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

Looks great! And hopefully your misfire problem is solved.

Reviving an old thread to add some more information that might help a 996/997 owner some day: While sitting at a stoplight, my 2003 996.2 suddenly started running rough, as if one cylinder was not firing. The check-engine light turned on. It ran rough with the CEL light on for the next hour of driving until I got home. My OBDII reader gave codes P0300 (random/multiple cylinder misfire detected), P0301 (cylinder 1 misfire detected), P0303 (cylinder 3), and P0305 (cylinder 5). This says to me that it's not a problem in one bank (which would be in cylinders 1-3 or 4-6) and not a fuel delivery problem. My gas tank was half full, so it's not from an empty tank. I replaced fuel pump earlier this year. I cleared the codes, ran the car some more, and there was only one code: P0301 (cylinder 1). Maybe it was just cylinder 1, which is more likely than 3 separate cylinders in different banks going bad at exactly the same time. I pulled the cylinder 1 coil. It's my newest coil, made by Beru, with 50 kmi on it (the rest are original, with 90 kmi; I'll replace these when I change the plugs in 20 kmi more). I had replaced this coil earlier because the original was cracked because the overflow hose for the coolant reservoir dumps right onto the coil (and still does, as I cannot find a better place to move it to). The old coil looked fine and had the same resistance (between the outside pins) as a new Bosch coil (part number 0.986.221.016). I pulled the plug, which only had 10 kmi on it and it looked fine as well. It was still screwed in tight. I replaced the plug (tightened with a torque wrench to 28 N-m as before) and coil. After 30 minutes of driving, I see no codes. One guess for what happened is that I somehow got a bad ground connection to the spark plug over time. I put a small amount of nickel anti-seize on my plugs, which has always prevented problems with the steel plug binding to the aluminum head and damaging the head in various cars. Porsche recommends not using anti-seize due to the potential of a bad ground connection to the plug's threads. I will post an update if the problem returns.

Thanks for searching, I always insure there is enough silver colored anti-sieze on sparkplug threads & all exhaust fastener threads before installing. Enough meaning as thin a coat as I can apply to the threads. It's more of a film than a coating.