J Berk

So I had the dreaded p0302 today. Was driving to a store when the car began to idle rough. I heard the misfire... Got a CEL... Which then cleared it self and so did the misfire. Car was fine on the way home. Checked for codes and only found the pending code but nothing remaining. So should I cry and sell the car? :-)

Ahsai

How old are the plugs and coils?

996AE

Just went through this on P0306 cylinder 6.

New coils, plugs. Checked plugs and coils again, all connections and switched 5 and 6 coil. No change. Flipped injectors. No change.

Two shops to run it down. First shop wanted to drop motor and inspect valves and lifters.

Second shop ran full dianostics to confirm nothing broken or bent including leak down. Then drained two quarts of mobile one and added two quarts ATF. Told to run it 100-200 miles and then drain and refile with 0w40.

Intermittent lifter or valve sticky was their call. This after ruling out coil, plugs, injectors and connections.

Post ATF drain now 200 miles and no codes. Running and idle smooth.

J Berk

The car definitely needs Coil packs... I knew that from the PPI when I bought it... 2 years ago.... I think it's time!

Schnell Gelb

Was it raining ? That would hint at cracked coils.
Plugs ,Tubes, seals at the same time?
Note the ATF fix mentioned above - 2 qts. very roughly 20-25% ATF in the sump.

Medevack1

Mine has been to a total of 3 indys and 2 certifies Porsche dealerships and still nothing, my 911 is a 04 40th Ae with 156k I everything that everyone has said its been done, coils, injectors, sparkplugs, leak check, compression test... etc etc so has the cel come back? the issue with mine is that it only does it at Idle, while driving the p0302 cel doesn't come on but when i come to a stop and the car idles she starts sputtering and cel starts flashing. but once I get back on the road and RPMs go above 2k the cel automatically goes away if I rev the engine while at idle the cel goes away, if while driving the cel comes on if I turn the car off and back on the cel goes away.

Medevack1

808Bill

Did you try the ATF as mentioned above?

996AE

400 miles all good.

Injector and ATF treatment at the same time so intermittent check engine light from sticky lifter or injector?

ATF cant hurt.

Hotrodaxel1976

My car was doing this exact same thing. But Mine was showing multiple misfires at the same rpm across cylinder 123. I could clear the code and drive at highway speeds and everything was normal. But as soon as I slowed the rmp drop and boom cel light up and blinking, as soon as I would give gas, cel light disappeared. The car is in the shop getting the variocam tentioner replaced, Indy said it was not working when I took it to him to diagnose. Timing was off at idle and misfire, but when given gas the misfire went away, but there was a deviation in timing that was out of spec. The Indy tried to activate the variocam tentioner and it would not respond. My car had no power tho, I mean No Power, Getting it back soon and I hope its fixed, there replacing chain guides and tentioner and silonoid.

996AE

How many miles on car?

Medevack1

mine is 156k this weekend i'm going to do the ATF and the injector cleaner.... and see what happens

AWDGuy

ATF? Automatic trans fluid??

Noz1974

Yeah putting atf in the oil for a short period before an oil change can clean crap out of lifters as there's a cleaning additive in it, this works quite well apparently I just worry what it could do to the bearing surfaces and bored etc, anyone know if it's safe, I've got a stick lifter I could do with treating !