Porsche 996 turbo 2001 misfire
Discussion
After a perfectly normal 50 mile run in my car I parked her up and went shopping for an hour, got back in her went 100m and a noise on the left nearside rear starts which sounded like something hitting the underside of the car every one revolution of the wheel as it went round and she starts misfiring at idle and in every gear, engine light on, sometimes flashes too. Feels like she's running on 3 cylinders but hard to tell. Cars done 73k miles FSH. Dash says drive to workshop. Engine pressures ok, oil level ok, coolants ok, smells rich at a standstill probably due to the misfire? Comprehensive rundown I know, just eliminating the obvious,any suggestions appreciated
Ordered 6 plugs and coils but while I wait I cleaned the MAF sensor, looked like new, checked the air filter and all wiring in the engine bay, all clear, doesn't look like any broken wires underneath either. Because its cold at the moment when I started the car last night normal water vapour was showing on the right exhaust but little on the left hand side suggesting to me it's not firing on 1,2 or 3 or maybe all three? Smells rich due to un burnt fuel on the left exhaust. When inspecting the fitted coils they do have water dew on them but until I take them out it's hard to see any cracks yet. I'm just surprised there was no build up to the misfiring say days before, she was fine one hour before then misfiring and sounding like a Subaru??
MAF sensor failure doesn't produce such an abrupt misfire - sounding like a Scooby as you say! MAF sensor failure also usually throws up dashboard lights - check engine and traction control if I remember correctly.
These coil packs are notorious for sudden failure - have a google round or look on this forum and you will see, it's a common failure. And inspecting them is pointless - they don't show outward signs of failure, or need to crack etc. to fail.
I have had them fail on my 996 on many occasions, and it happens at the click of fingers - never get any warning or misfires. One minute everything is fine, the next - scooby sounding engine! I have had one fail overnight once too - parked up, all good, next morning - misfire.
Having said all that - difficult to truly diagnose via the internet, I am saying it is PROBABLY your problem, but not definitely obviously! Good luck either way, and let us know how you get on matey.
These coil packs are notorious for sudden failure - have a google round or look on this forum and you will see, it's a common failure. And inspecting them is pointless - they don't show outward signs of failure, or need to crack etc. to fail.
I have had them fail on my 996 on many occasions, and it happens at the click of fingers - never get any warning or misfires. One minute everything is fine, the next - scooby sounding engine! I have had one fail overnight once too - parked up, all good, next morning - misfire.
Having said all that - difficult to truly diagnose via the internet, I am saying it is PROBABLY your problem, but not definitely obviously! Good luck either way, and let us know how you get on matey.
Received my OBD2 reader, plugged it in and it came up with multiple misfires on all cylinders?? So I cleared all codes and turned the car off and left her for 10 mins then started her again after checking under the car and spraying all coils with WD40 then only a misfire on cylinder number 2 only? Tried to clear the code again and number 2 kept coming up? Received 6 new coil packs and sparkplugs today, changed number 2 sparkplug and coil only without removing wheel,bumper or turbo (not easy on the floor under the car in freezing wind outside) and hey presto she spluttered for a couple of seconds but she runs great now, initially had cylinder 2 code again even though the engine was running fine but soon cleared it on the OBD2 reader. Changed all three coils and plugs on the same bank and plan to do the other side tomorrow when I've thawed out. Thanks to all the advice, my mind is now at rest for Christmas and hopefully some good driving too.
Desmo jay said:
Received my OBD2 reader, plugged it in and it came up with multiple misfires on all cylinders?? So I cleared all codes and turned the car off and left her for 10 mins then started her again after checking under the car and spraying all coils with WD40 then only a misfire on cylinder number 2 only? Tried to clear the code again and number 2 kept coming up? Received 6 new coil packs and sparkplugs today, changed number 2 sparkplug and coil only without removing wheel,bumper or turbo (not easy on the floor under the car in freezing wind outside) and hey presto she spluttered for a couple of seconds but she runs great now, initially had cylinder 2 code again even though the engine was running fine but soon cleared it on the OBD2 reader. Changed all three coils and plugs on the same bank and plan to do the other side tomorrow when I've thawed out. Thanks to all the advice, my mind is now at rest for Christmas and hopefully some good driving too.
Good news, and happy to help 
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