CEL issues - 986 Forum - The Community for Porsche Boxster & Cayman Owners

Frodo · 06-01-2010, 04:47 PM

Have had a CEL (NON-flashing) on and off for awhile. 3000 miles ago (when the car had 48K miles), I took it in to a local Porsche place. The guy did diagnostics on it, which indicated "misfire, cylinder 1". He said it was very short-lived, could have been due to any number of innocuous reasons, and said I shouldn't worry. He reset the CEL and recommended "drive her hard" on the way home. I did, and everything's been fine since...until yesterday.

CEL returned, and I went back. Durametric readout again indicated "misfire, cylinder 1". The mechanic said it had occurred three times, all at very low RPMs (eg 700 RPM)---he seemed to think it occurred when I was cranking her, ie before the engine had really even started. He again seemed to think there was nothing to worry about, that I could probably go until the 60K maintenance to have it checked out, but also said I could pull the spark plug and take a look if I was curious. He reset the CEL and I went on my way. The 20-mile trip home was fine, no issues. However, I shut the car down at home, then went out like half an hour later and drove off. Got maybe 1/4 mile and she started missing noticeably, especially at low RPMs. I hobbled home and decided to pull the cylinder 1 spark plug.

Did so. As far as I can tell, the plug looks OK. I'm kind of a newbie when it comes to Boxster mechanics, so I'm really not sure. Anybody have any insight here?

Assuming the plug is OK, what would my next move be? If I take the coil pack and the spark plug in to a dealership, could they test the coil pack for me (as well as assessing the plug)? I haven't pulled the spark plug well (tube), but (inserting a clean finger in there) it seems to be clean and without any obvious issues.

What should I do next?

extanker · 06-01-2010, 05:09 PM

look at center of plug [white insulator] for cracks,carbon tracks. check outside shell for cracks,carbon tracks.look in coil boot for black line [carbon track] put in new plugs

Frodo · 06-01-2010, 05:23 PM

Thanks, I'll do that...soon as I find me readin' glasses!

Steve Tinker · 06-02-2010, 12:08 AM

You could also try putting the suspect plug into cylinder #2 and see if the problem moves with the plug. If the Durametric still shows a problem with #1 cylinder, then there's a good chance you have a faulty coil.

Frodo · 06-02-2010, 01:29 AM

Another insomniac, I see...

Yeah, I thought about that (switching plugs). Didn't really feel like taking another one out if there's any chance the coil pack/spark plug unit that I pulled could be tested independently (ie, without messing with any of the other "good" ones).

Does anyone know if that can be done?

paulv · 06-02-2010, 03:56 AM

Quote:

Originally Posted by Frodo

Another insomniac, I see...

Yeah, I thought about that (switching plugs). Didn't really feel like taking another one out if there's any chance the coil pack/spark plug unit that I pulled could be tested independently (ie, without messing with any of the other "good" ones).

Does anyone know if that can be done?

I would take what Steve T recommended and take it a step further by moving the plug and the coil pack to different cylinders to isolate whether it is the plug or the coil.

Since you have the Durametric tool, you should be able to read the freeze frame data that was captured when the CEL came on (especially for misfire faults). If you can retrieve this data, please post it as it can help us help you. I'm particularly interested to see how the fuel adaptation is working.

Regards,
paul...

Frodo · 06-02-2010, 04:35 AM

I may do that. Actually, however, you misunderstood me...unfortunately I don't have a Durametric (wish I did!!). That read out was at a semi-local shop (maybe 20 miles from here) that does a lot a Porsche work (including track vehicles, restorations, etc.)

paulv · 06-02-2010, 07:18 AM

Quote:

Originally Posted by Frodo

I may do that. Actually, however, you misunderstood me...unfortunately I don't have a Durametric (wish I did!!). That read out was at a semi-local shop (maybe 20 miles from here) that does a lot a Porsche work (including track vehicles, restorations, etc.)

Sorry for the misunderstanding -- in that case, go to an Autozone or some place similar who can read the codes and hopefully provide you the freeze frame data (if available). Going back to that shop and asking them for this info is like going to a restaurant and asking the chef for the recipe! I never feel comfortable while trying to pick some pro's brain so I don't have to pay him.

Besides ignition issues, misfires can occur from injector system problems, air/fuel mixture being way off, and valve lifter problems.

Regards,
paul...

Frodo · 06-02-2010, 11:15 AM

Thanks, Paul, I appreciate it.

On the way to work, I stopped at my "regular mechanic" and also at the local Porsche/Audi dealership. They told me basically the same thing as you did. Also that they couldn't test the coil pack OFF the car. Soooo, guess I'll pull the one for Cylinder 2, switch them, and have my mechanic reset the CEL. When it comes back on, I can see which cylinder it's for and know whether it's the coil pack or one of the other things they (and you) mentioned.

BTW, I know what you mean about picking their brains at no charge. However, I don't feel too bad in my case. With my regular mechanic, I've been going there with all my cars for going on 14 years now. Between us and our kids, we have several cars we take there for all kinds of servicing, so he does good business with our family. As far as the Porsche dealership, I do go there for repairs from time to time and, of course, they charge me an arm and a leg...so I don't feel too bad about occasional attempts at getting free advice there either

KevinH1990 · 06-02-2010, 04:26 PM

If it is any help, I had the same problem a few weeks ago with cylinder 4. My misfiring cylinder had a noticeable effect on engine operation, so it seems like my problem was more severe than yours. I couldn't see a defect on the spark plug so I changed the coil pack on that cylinder and it fixed the problem.

I wish I had thought about switching the coil packs to be sure of my diagnosis. The part was around $55 with shipping and I didn't like guessing that was the problem.

Frodo · 06-02-2010, 05:22 PM

Thanks for the input. I had actually thought about just replacing the coil pack on a hunch...don't think that would have worked, though. With the two coil packs from cylinder 1 and 2 switched, I still was throwing an (intermittently flashing) CEL. (AND, at this point she's running pretty rough.)

Got to talkin' with Dave (my "regular mechanic") after the diagnostic readout, which no longer supported the simple diagnosis of a bad coil pack (was still reading "cylinder 1 misfire", and some other random codes). He started talking compression testing and a lot of other even more intimidating diagnostics...and I threw in the towel. (I'd be a lot more inclined to try more of this IF I only had a lift!) "Dave, you feel like fixin' her?" I asked. "Sure" he said.

Sooooo, he's going to tackle it...I just don't have the time right now... not enough hours in the day.

I'll keep everyone posted.

KevinH1990 · 06-02-2010, 06:05 PM

I know what you mean about time. There's also the inconvenience of being without the car while waiting for parts or an opportunity to work on the car.

My wife bought me a used Durametric for Christmas and I was able to scan the car myself. My fault codes were:

P0300: Porsche fault code 62 - misfire damaging to cat converter

P0304: Porsche fault code 66 - Cylinder 4 misfire damaging to cat converter

The CEL wasn't flashing, but I didn't want to drive it to my mechanic because of the message about damage to to the cat. So it was either flat bed it to the shop or as you say "play a hunch." I felt lucky - this time.

Good luck with your repair.

boxster_s_boy_34 · 06-26-2010, 02:03 PM

Quote:

Originally Posted by Frodo

Thanks, I'll do that...soon as I find me readin' glasses!

This is the problem with most boxster owners; they're old enough to have boner problems and poor eye sight.

Frodo · 06-26-2010, 02:34 PM

Quote:

Originally Posted by boxster_s_boy_34

This is the problem with most boxster owners; they're old enough to have boner problems and poor eye sight.

Very astute observation on your part, young fella...except in my case, you're only half right.

boxster_s_boy_34 · 06-26-2010, 03:59 PM

Very good sense of humor. We should B/S some time, but I go back to Iraq on Tuesday. Also, that's the kind of hard time that I get from my friends even though I'm 24.

extanker · 06-26-2010, 04:33 PM

Quote:

Originally Posted by boxster_s_boy_34

Very good sense of humor. We should B/S some time, but I go back to Iraq on Tuesday. Also, that's the kind of hard time that I get from my friends even though I'm 24.

be safe and come back to enjoy your car...thats an order trooper

Lil bastard · 06-26-2010, 06:34 PM

There are 3 predominant reasons that code is thrown; Bad Coil Pak, Bad MAF, Bad Plug.

Bet the answer lies in one of these 3.

Cheers!

Frodo · 06-26-2010, 07:02 PM

Quote:

Originally Posted by Lil bastard

There are 3 predominant reasons that code is thrown; Bad Coil Pak, Bad MAF, Bad Plug.

Bet the answer lies in one of these 3.

Cheers!

You win the cookie! Coil pack...I came so close to getting it figured out, but on that test drive (with coil packs switched) it was running so rough (with intermittently flashing CEL) AND I was already heading towards the shop I use I just decided to let him handle it.

Quote:

"be safe and come back to enjoy your car...thats an order trooper"

Originally posted by extanker.

Hey, ditto that for me. Be careful over there, watch your back.