MrKieranHale
New member
Hi there,
I bought a 2004 986 Boxster S a couple of years ago, which has just ticked over 88,000 miles and it's beginning to misfire.
Just to give a bit of history on the car, I had the car serviced by a Porsche specialist local to me in June before I was going to take the car to do the NC500 towards the start of August. The work carried out was a minor service, using 5w50 Mobil A40 oil (if the invoice is correct), and replacement of the manual gearbox fluid.
After this, I began to notice the car was misfiring and the dreaded white smoke. I began trying to diagnose the car and notice that one of the coil packs was ever so slightly unplugged and that there was a pretty heavy build-up of oil in the plenum coming from the air oil separator. Thus, a new air oil separator was ordered from Design 911 (and new Iridium spark plugs and Beru ignition coils for good measure as I didn't have the history for when these and last been replaced.) The issue seemed to go away.
Design 911 part numbers for these if anyone is interested,
Air Oil, 99610702602
Spark Plugs, 9991700IK20
Ignition Coil, 99760210404/1
Come to yesterday the misfiring issue has reared its lovely head again.
It has been misfiring enough to flag a check engine light, firstly P0305 (generic cylinder 5 misfire).
Then after a little more driving on the motorway P0300 (random/multiple misfire), P0305 (cylinder 5 again), P0304 (cylinder 4) and finally P0303 (cylinder 3) - the exact same codes it was flagging before I replaced the AOS a couple of months ago.
My troubleshooting steps so far have been to disconnect the hose from the AOS to the plenum and noticed quite a bit of oil building up in the pipe (after the car has been sat for 12 hours), as well as a slight bit of oil on the opposite side of the throttle body. Though a bit more worryingly there was a slight in the plastic which lead to it snapping as I was trying to manoeuvre the hose out of the way. I haven't gone through the steps of looking at the coil packs as I'm not in a position where I can get the car jacked up to get a proper look at
them.
I did see a video from La Rose Porsche when they had a 986 in with AOS failure and they tested it by trying to take the oil filler cap off while the car was running it was impossible, though after the AOS has been replaced it comes off as though the engine isn't running. Trying it on my car yesterday, it was impossible to get off.
Has anybody had experience with an AOS failing again after 4 months of it being replaced or a split hose causing enough of an issue to create the same symptoms as a failed AOS?
Also, has anybody had any experience running a lighter oil with the AOS?
Any other insight would be welcome as I'm really clutching at straws at this point hoping it's nothing majorly wrong with the car.
Look forward to any insight anyone might be able to bring,
Thanks, Kieran.
I bought a 2004 986 Boxster S a couple of years ago, which has just ticked over 88,000 miles and it's beginning to misfire.
Just to give a bit of history on the car, I had the car serviced by a Porsche specialist local to me in June before I was going to take the car to do the NC500 towards the start of August. The work carried out was a minor service, using 5w50 Mobil A40 oil (if the invoice is correct), and replacement of the manual gearbox fluid.
After this, I began to notice the car was misfiring and the dreaded white smoke. I began trying to diagnose the car and notice that one of the coil packs was ever so slightly unplugged and that there was a pretty heavy build-up of oil in the plenum coming from the air oil separator. Thus, a new air oil separator was ordered from Design 911 (and new Iridium spark plugs and Beru ignition coils for good measure as I didn't have the history for when these and last been replaced.) The issue seemed to go away.
Design 911 part numbers for these if anyone is interested,
Air Oil, 99610702602
Spark Plugs, 9991700IK20
Ignition Coil, 99760210404/1
Come to yesterday the misfiring issue has reared its lovely head again.
It has been misfiring enough to flag a check engine light, firstly P0305 (generic cylinder 5 misfire).
Then after a little more driving on the motorway P0300 (random/multiple misfire), P0305 (cylinder 5 again), P0304 (cylinder 4) and finally P0303 (cylinder 3) - the exact same codes it was flagging before I replaced the AOS a couple of months ago.
My troubleshooting steps so far have been to disconnect the hose from the AOS to the plenum and noticed quite a bit of oil building up in the pipe (after the car has been sat for 12 hours), as well as a slight bit of oil on the opposite side of the throttle body. Though a bit more worryingly there was a slight in the plastic which lead to it snapping as I was trying to manoeuvre the hose out of the way. I haven't gone through the steps of looking at the coil packs as I'm not in a position where I can get the car jacked up to get a proper look at
them.
I did see a video from La Rose Porsche when they had a 986 in with AOS failure and they tested it by trying to take the oil filler cap off while the car was running it was impossible, though after the AOS has been replaced it comes off as though the engine isn't running. Trying it on my car yesterday, it was impossible to get off.
Has anybody had experience with an AOS failing again after 4 months of it being replaced or a split hose causing enough of an issue to create the same symptoms as a failed AOS?
Also, has anybody had any experience running a lighter oil with the AOS?
Any other insight would be welcome as I'm really clutching at straws at this point hoping it's nothing majorly wrong with the car.
Look forward to any insight anyone might be able to bring,
Thanks, Kieran.