Hello everyone! I have a 2009 4S with an extensive service history and high mileage. Ive been experiencing a strange idle then it started to misfire on cylinders 4,5,6. When im driving fast feels like no problem. But at idle and low speeds its pretty bad. Changed spark plugs and ignition coils (ignition coils original). Did a vacuum leak test with smoke all good there. Any other suggestions on what it could be?
Getting codes
P0304
P0305
P0306
P0300

Car currently has 220k kms. Fuel pump was replaced.
Tried looking online but most people either have a 997.1 or they say coil packs.

 

Sounds similar to this :
Idle misfire stumble fixed

BTW Awesome as that solution is, you don't have to fix the solenoids, you can just replace with new ones.

Keep in mind it can possibly also be O2 sensors.

 

Yea right after i posted i found that post. Going to try changing them and if not o2 sensors.

 

I had the exact same problem with the same codes. Replaced the coil packs and haven't had a problem since. Good luck!

 

If you have a proper scan tool, check camshaft deviation #s between the 2 banks. If the Camshaft Position Sensor for bank 2 has failed, you'll get misfires on only that bank and the car will run really rough at idle, but less so underway. When I had a similar issue with my 997.1, this is what the live data looked like.



The one that is reading 0s is the failed sensor. Replaced it and the problem was immediately fixed.

 

I had same one bank misfires, simple replacement of variable valve solenoid complete cure. Easy to do

 

I replaced the camshaft solenoid sensor. Still misfire. One of the mechanics is saying the Variable valve solenoid is the same as the camshaft sensor. Which i did not agree with but im not to knowledgeable on porches. Im most likely going to order that sensor myself and give it to them.


Never mind. I guess i said it improperly to them. They changed the Variable valve solenoid. Not the camshaft sensor. Ill give it a scan.

 

Hi. I am going through the same process right now. 997.2 with 133k miles. Threw a CEL and same codes as you. The plugs and coils were due so I changed them. The car ran better but still seems off and I can hear a different sound as the revs get above 3k. Then after a couple days I get CEL again with a new code P1382. I just ordered the variocam solenoid and will replace that hoping that’s it. There have been a few of these on the 991 board so it seems likely.

 

Yes, 2 different things there. One is a sensor and the other is a solenoid that actually moves the camshaft. If the CELs come on the first time only above 3,000 RPMs (more likely 3,500-3,800 RPMs) that's when the variocam plus should be moving the camshaft to run on the alternate lobes for higher lift and greater duration. If the DME is expecting that and it doesn't HAPPEN or it sees it happen on one bank but not the other, it throws the CEL.

For information purposes, if it was the camshaft position sensor, it would throw a code as soon as the start up protocol completed, even at idle.

 

The cel turns on as soon as I start the car and misfiring. My scan tool does not show the sensor readings because it's a simple scan tool. Going to do a compression test on Thursday but right now I'm just going to order that sensor. Hope it's the issue.

 

Will it throw a code for the sensor itself though? And is it called camshaft position sensor or something else?

 

Camshaft position sensor (hall sensor).
99760610603
Fcpeuro

 

Yep ordered it from dealer. Not the cheapest but the fastest way.

 

No need for a compression test. You don't have 3 cylinders that have all lost compression. You need to find something common to only that bank, like a vacuum leak on the plenum feeding that side or something with the valve train on that side like a variocam sensor or solenoid.

 

Already replaced that solenoid and did a leak down smoke test. Only thing remains is the camshaft sensor.