Check Engine Drive - P0300 - P0305 - Misfire Error - Last İnformation And Questions:(
12-16-2015, 06:51 PM
#31
Rennlist Member
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.
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.
12-16-2015, 07:06 PM
#32
Rennlist Member
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.
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.
