vsp1216

First time post!

I am a relatively new Porsche owner after buying a 2006 Cayman S last summer. Has the 3.4L flat six (Not DI) with 32k miles when I bought it, has 36k miles on it now. Only mod done was an aftermarket catback exhaust and K&N air filter from the previous owner, otherwise completely stock power train.

As the temperatures have dropped, I've been getting a misfire on start up only. It'll start up, I can hear the secondary pump running, and it seems to stumble around with a rough idle. Depending on the temperature and how long I've let it sit, the idle will be even worse. I always get a P0301 fault now (misfire cylinder 1.) Some circumstances, it'll be accompanied with a P0300 (multiple misfire) and rarely alongside with a P0303 (misfire cylinder 3.) I originally swapped coil packs from cylinder 1 with cylinder 3, but after reading yesterday on the Boxster forums, the even cylinders are on the drivers side of a LHD Porsche. I swapped the two coil packs on the drivers side of my LHD Cayman. After swapping coils (of what might have been with wrong cylinders) I got the P0301 fault again. So I then swapped spark plugs and also got the P0301 fault. Then I took it into an independent shop, which stated that he did see the misfire on the history but said the car drives exceptionally well for an 06. He said it pulled as fast as a Gen2 Cayman, based on his opinion. He said he couldn't regenerate the same fault, which is what I expected since it's already warmed up. I've driven it more then 150 miles after a cold start on a relatively cold day with the misfire, yet after the misfire, not the slightest of malfunction the remainder of the day. The fault only occurs on cold start ups. Also, on days greater then 50F ambient temperature, I will most likely not get a misfire. If below 50F, I will get a misfire. And the single digits temperature start up like last week, I actually had smoke, which smelled like motor oil, until the secondary pump shut off, in which I just had steam and a normal aroma from the exhaust.

Any ideas? I've looked for a couple days and can't seem to find a solution. I know that I do need to swap the other coil packs and spark plugs, but since I just exceeded 36k miles, I just received the spark plugs for my 36k miles service. Any help would be greatly appreciated, and thanks ahead.

Macster

I'm not a fan of swapping plugs. I treat plugs like a use once and discard item.

Often misfires are due to plugs or coils (I think coils more often than plugs are to blame).

Are the plugs original?

I'd be tempted to replace both all plugs and coils.

Based on my experience, though I suspect coils are to blame. But the plugs should still be changed.

Both of my cars have misfired upon cold start a few times. Sometimes this misfiring is after the car has sat out in the rain or heavy fog overnight. Other times it was after just being out when the weather changed from mild/dry to cooler and more humid.

The misfiring is at cold start and is brief and never occurs again under any other driving conditions. I had the plugs changes in both cars -- the plugs were due -- but really the coils should have been changed too. However, I balked at this expense but I have coils down to be changed next plug service unless the coils get worse in which case I'll have them changed before the plugs are due again.

Also, my advice would be to go back to the stock air filter setup. Afterwards carefully remove the MAF and clean it with the proper cleaner then re-install the MAF.

Spokayman

I agree with Macster on changing the coils and plugs, and also cleaning the MAF.

The only time I have experienced a misfire is upon a cold start following a very brief running of the engine.
For example if I start the car cold and pull it out of the garage and turn it off after having run for just a minute, it may run rough when I start it again. The rough running goes away within 15 seconds or so.
This has happened maybe 3-4 times in the last 4+ years.

vsp1216

Thanks a lot for all of the information Macster. I have ordered the kit for the 36k mile service including a genuine porsche paper air filter. I also have spark plugs but I'll order coils as well. Try those out and see where it goes. They aren't the original spark plugs based on the information from the previous owner, who said that he changed them himself a couple years back. He said the coils are the originals, however. I do live in a relatively humid location, and I also wash my cars in the garage when we are below freezing outside. I might get up to 65-70% humidity in my garage along with temps down sometimes into the forties inside my garage during those periods. I run my dehumidifier but it takes a couple days to catch up to 50-55% humidity in my garage. So maybe that is a culprit as well. But I will get on those things, as well as putting the stock catback on and cleaning the MAF. I like the exhaust but my girl isn't a big fan. I appreciate the response and direction. Might take me sometime as we have our trip coming up but as soon as I have parts ordered and complete, I'll provide feedback on the results.

Macster

The exposure to humidity your car experiences probably accounts for the part of the problem. At first this doesn't really affect the car but after some time and miles the coils get a bit sensitive. For years my Boxster has been exposed from parked outside in all kinds of weather. But in the last couple of years a few times it has misfired upon cold start yet not at any other time. The coils are just more sensitive to the dampness. (My Turbo has likewise begun to react to being left out side in wet or just damp weather.)

You can replace the plugs and coils and hope for the best. There is the slim possibility the problem is something deeper but to eliminate this or confirm the plugs/coils are all that is wrong can require a professional tech's expertise.

vsp1216

I am worried that there might just be something bigger, but I'm hoping for the best. First things first is to rule out the normal items as you've noted. Hearing feedback about the moisture and misfire of other owners alleviates some of that tension greatly though. I've read many pages after googling the same scenario of people who never find a conclusion to this same specific issue, including getting assistance by the experts of Porsche's technical teams. Even with warranties, I've read of people who just completely give up on the car and trade it in. One case I've read was an individual who even used his warranty to swap out the entire motor only to have it come back years later. So far, I am unaware if my faults will disappear in warmer months and/or revive themselves in colder weather, but I am definitely noticing a clear correlation with temperature and the misfire faulting, as our winter this year here has been much more chaotic then my memory can recall from years past. Only time will tell, but the advice and reoccurrence of others brings much hope and direction.

Macster

Relax.

Most of the time the misfire is cured by plugs and coils. (Most of the time it is the coils. I've run plugs once or twice past their change by miles limit and the engine wasn't misfiring. Now I'm not recommending one press his luck I'm just saying in my experience plugs have some margin. 'course, this doesn't mean every engine will have this same margin which is why plugs should be changed on schedule.)

Now you have to be sure this job is done right. Use the right plugs. I'm sorry but I have to expand on this and advise you to avoid trying some "comparable" plug even if the plug compatibility charts indicate the plug you want to use and the plug that should be used are interchangeable. I know of at least one case where a Cayman owner used a plug based on a chart and the plugs proved to be unsuitable and he had to swap them out.

I know it isn't very "sexy" but I just use, or the techs just use, whatever the parts department manager at the dealer shoves over the counter. I have no interest in using my engines as test platforms to try to find other suitable plug choices. I'm perfectly happy with what the parts department supplies and more importantly the engine is perfectly happy.

Next I have to stress the plugs must be installed sans any thread lube.

And be sure they are properly torqued down.

Be sure the coils are installed correctly. If the coil is not securely connected to the plug or if the coil is not properly connected to the wiring harness it can still misfire.

If you do this work yourself take your time and be sure you do a good job.

If you have this job done at a shop be sure you pick a shop that has a good rep with Porsches and uses the right parts. Often an indy shop uses other plugs as it services a number of other cars or Porsche models and tries to cut down on its part inventory overhead and increase its profit margin on parts by buying parts in bulk and making one size, so to speak, fit all.

While this helps the shop it sometimes is not what is best for the engines.

vsp1216

Sorry for the long delay, it's just been a long time since I did swap out the coils and the spark plugs. I eventually got to swap them out when we came from from California in mid Feb. Seeing as it was still relatively cold and snowy around that time, I wasn't really driving it. The first time I did fire it up with the new spark plugs and coils, got the P0301 fault again. But I thought I'd let it wait and try the next time, and sure enough, no misfire on startup. But since then, the misfire has comeback.

The actually swap of the plugs and could was actually easy, in my opinion. I did take my time, didn't use lube, ordered parts from pelican parts, the job went very smoothly. When doing the swap, I found cylinder 1 and cylinder 5 had their coil packs cracked. I figured maybe some moisture was getting in there and was hoping as the culprit for my misfire. Alas, new cool packs and plugs and the misfire still exposes it's head from time to time.

I read from another's post of the AOS causing a misfire, so I ordered a new AOS. I got the original AOS, not the 996 or the motorsports heavy duty AOS that's better suited for track performance. The swap of the AOS went very smoothly as well. I did have to run to the store to buy some better right angle pliers, but for a first time, maybe two hours. Alas, the misfire still lives. So back I am, asking any members for advise.

I did speak to a previous Cayman 987.1 owner hat I meet online, and he noted of having the cold misfire on his vehicle as well. What the dealership found was his injector wasn't firing on cold startup. New injector and the issue went away. He lives in Georgia, where it is a little warmer there. Here in Indiana. From my history, the misfire doesn't occur in warmer days, as the entire summer last year had no misfires on start up. It is starting to warm up here and I did get a misfire here in the sixties, so perhaps my issue is getting worse.

Any help again would be appreciated. Thanks Rennlist.