alshulski

Hello all. Seeking help on this issue as I have spent a majority of the day trying to diagnosis/fix this. It started just after replacing my bank 1, sensor 1, O2 sensor (got an error code and CEL about a week ago for this). Since I had to jack the car up and get inside the wheel well, I decided to change out all of my spark plugs today as well. Once the car was lifted and the O2 sensor was replaced I went to change my spark plugs on the bank 1 side. The plug in cylinder 3 came right out and I replaced it with a new one. The cylinder 2 plug would not move for the life of me. I tried every trick I could find online but there was so much resistance in trying to loosen it that I eventually gave up as to not cause any (or further) damage. I move on to cylinder 1 and same issue as 2. I inspected the old spark plug I replaced and it actually did not look that bad so I figured I would attempt to change the remaining 5 out at a later time. Dropped the car back down and after starting it, it did not sound normal. Idle was pretty rough and sure enough a blinking CEL came on. Grabbed my scanner and got the following error codes:

P0300 : Random/multiple cylinder misfire detected
P0302 : Cylinder 2 misfire detected
P0301 : Cylinder 1 misfire detected

Jacked the car back up, removed the coil packs and inspected both the cylinder 1 & 2 plugs sitting inside and the packs themselves. Everything seemed normal but I still tried to "re-install" everything as precisely as I could. I read some forums and threads online and thought it may be something with the O2 sensor so I reset the ECU as well. Started the car up (left in park) and although still sounding rough, the CEL did not come on. Upon backing out of my driveway the blinking CEL did come back on. I decided to drive just down the cul de sac as a test and to no surprise shifted and handled equally as rough as it sounded. During part of the drive the CEL did actually turn off but still performed just as poorly with it on. Did some more reading online and could not find anyone else having a situation like this. It was either one cylinder or the whole bank of 3. Never saw anything with just 2.

If you have any pointers/thoughts/tests I would absolutely listen as I am officially lost. My thought are either I damaged the spark plugs when trying to remove/reinstall, or there is an issue with the o2 sensor I received.

FYI - iCarsoft POR-II scanner was used. Car is a 2012 987.2 Boxster.

ZuffenZeus

Normally, misfires are associated with aging - faulty coil packs not spark plugs. That's what I experienced with mine. Over time, the heat causes them to crack which in turn makes them malfunction.

TMc993

b3freak...I'm going to disagree with you. OP had an O2 sensor CEL and replaced the sensor but didn't restart the engine to see if it the CEL had cleared. Then he probably put some pretty good force on the #1 and #2 plugs trying to dislodge them. Then, when he did start the engine he got a misfire CEL in place of the O2 sensor CEL.

Unless the act of just removing the coil packs will cause them to go bad, I'd be focused on the two seized spark plugs because there's a good chance they were damaged during efforts to remove them. Even if they aren't damaged, they need to come out and be replaced along with the rest. Once all of the plugs have been replaced, if the misfire CEL is still present, he can focus on the coil packs.

Just my opinion.

deilenberger

That would be true in most cases - but in this case, the OP had difficulty in R&R of the plugs in 1 and 2.. I'm guessing if the socket went a bit off-angle, it's possible the ceramic on the plug has been cracked, causing the misfires.

I think at this point the car had best go visit a professional before further damage is done to it.

deilenberger

@TMc993 - I see we both think alike. Comes from BTDT sort of experiences..

TMc993

Exactly! I've sheared off exactly one spark plug in my 60+ years of working on engines...Left the threaded section flush with the recess in the head...Not a good day.

alshulski

Hey guys. I appreciate the insights. I did want to do one last test to rule out the coil packs. I swapped the coil pack on cylinder 3 with the coil pack on cylinder 2 (since there was no error codes on cylinder 3). Went for a short test drive and although not getting a CEL, my scanner still detected the same error codes for misfires on cylinder 1 & 2. I think at this point I am fairly certain the spark plugs in cylinders 1 & 2 were damaged so I plan to take it to a shop tomorrow.

TMc993

Nice diagnostic work. Let us know how it turns out.

alshulski

UPDATE 2 : Car is back from the shop and running even better than before! I did indeed crack both the spark plugs in cylinders 1 & 2 (wish I kept them to show a few pics). Learned some tips from the guys at the shop about removing the plugs so hopefully will avoid this in the future. Thank you all for the comments and insights.

RennHarry

Please share the tips! I have never damaged a plug while removing it, but sometimes, when they are a little stubborn, my anxiety level redlines.
Cheers

TMc993

Good that it turned out to be something relatively simple and that you got useful information in the process.

ZuffenZeus

That's good news in spite of the damaged plugs. Glad to hear you got it all sorted out. Happy motoring!

kiznarsh

Yeah, this.

cavediver32043

Yup, I DIY changed my plugs and coil pacs ( no CEL/Misfires; car ran fine) due to age and cracking probability. ALL 6 had multiple crackes! Just a short matter of time before moisture in those cracks leading to misfire CEL..2007 CS w 38K; changed at 36K