I own a 2009 Cayman 2.9 that has 196k km's (122k miles) on it. For the 2,5 years that I own it, it has been faultless. It's been dealer maintained for all it's life.


A few weeks ago my wife and I were travelling in Scotland and when I went to park the car I made a (small) mistake; I let go of the clutch without checking if the car was in neutral. I had my foot on the brakes, so it just lurched forward a bit and stalled. Not a big deal, right?

So I shut the car off in order to start it again (I wanted to back up a bit), but whatever I did, it would not switch on the ignition. I then noticed that the key was stuck in the ignition barrel as well; I could turn it (with no effect), but I couldn't take it out.

The car was completely dead: the frunk and trunk wouldn't open, the windows wouldn't open, no lights on the dash, absolutely nothing.


I knew the battery was not the problem, as it was a year old and it had been performing flawlessly for the whole trip so far (5 days with a lot of kilometers).

Eventually, I found somebody with jumper cables, and I managed to open the frunk with the emergency bypass in the fuse box. It did take a few tries before it worked though. I then dis- and reconnected the negative terminal from the battery and the car came back to life.

It then started up like nothing happend.


I figured it had to do with the sudden stalling of the engine, because everything seemed normal after that.


The next day however, we got back in the car after a short hike, and it gave an error for "hold assist" (the hill hold function) and the "drive spoiler" (I don't remember the exact phrasing, but those 2 things gave an error). I clicked them away, but the drive spoiler error kept coming up. Like every 5 seconds or so.

While driving, I noticed the speedometer needle dropping intermittently. Then I noticed the engine to start sputtering very slightly, and the lights in the center console started flashing as well. It then went from very slightly to more noticeable, to becoming problematic. We turned of the motorway, and when we had to stop at a junction, I couldn't keep the revs up enough and the car died. Again, completely dead.


It was a whole ordeal to open the frunk again, but after dis- and reconnecting the negative terminal again, the car started like nothing was wrong. Only the left front indicator bulb had burned out.

After that the car performed flawlessly again for the remainder of the trip. I haven't used it much since we got home, but also for those few rides it worked great.


I do remember that a couple of days before the first breakdown, the car gave a "hold assist" (hill hold) error once before. I thought nothing of it, as it disappeared upon the next start up.


I bought a scan tool to read any codes, but any codes that might have been stored were already lost by the time we got home.

I think it might be a ground issue, as there are several (seemingly) unrelated things that fail simultaneously.


Does this sounds familiar to anyone? Or does anybody have any idea how I should go about diagnosing this problem?

We plan on taking the car on more road trips throughout Europe, but in order to do that with confidence, I would really like to get to the bottom of this.


Thanks!

 

It could be a ground issue. Removing, cleaning and reattaching grounds may solve your problem. However, random, seemingly unrelated error messages are often a sign of a weak/failing battery. Even though your battery is just a year old, I would have it load tested. If it is okay, but less than fully charged, I'd also have the alternator output tested. I'd also check the fuses/relays for any corrosion that may be impeding current.

As Malcolm of the Clan McLeod, I envy your travels in Scotland...

 

^ I second all of this. The main ground cable in the front of the battery/frunk compartment has been known to fail with age/corrosion. Is the car stored outdoors?

 

I would make sure that all ground connections are tight to begin with. That the problem is intermittent might suggest something being loose.

And your battery is secured properly with the factory clamp, correct?

 

There is a main pin the battery cable runs to. It's known to corrode and fail. There is a TSB and service kit ($$$) for it. This could be your issue. I'll see if I can find a thread about it for you. The lurch/stall may have been the straw that broke the camel's back. It could of course be something completely unrelated to this.

Edit: See if this thread, I posted some links in there.

 

I’ll check the grounds and fuses, and if that is all good I’ll have the battery and alternator tested. I would be surprised if it is the battery though, as it always starts strong.

And I really fell in love with Scotland! It’s one of the most beautiful countries I’ve been to, with the kindest people!

Thanks! I’ll check that first thing!
Sadly, the car is stored outdoors, but under a good car cover. And for the winter months it’s stored in open garage, out of the weather, under the cover.

I have an aftermarket negative terminal quick-disconnect on the battery. I did check that though, and it is tightly secured at both ends.

Thank you! I will check that out and report back!

Thank you all for your help so far! 🙏

 

I meant the securing clamp for the battery itself, at the side of the battery base. If the battery is able to slide around in its tray, it's possible it could short if the terminals or cable ends are making contact with something.

 

I have had a bad experience with terminal disconnects. I would consider that to be a prime candidate for your problem. I would go back to the stock setup and see if that makes a difference.
Normally, I would talk about using a meter to check resistances and voltages. But meters cannot duplicate the demand placed on connections when you are pushing major amps through them.

 

Hopefully you found a bad connection or battery problem by now but here is an odd fix….Batteries build up sulfate on the plates. The sulfate flakes off and drops to the bottom of the battery. In time that pile of sulfate gets high enough to short the plates in a cell and voltage drops to 10-11 volts. That is why a lot of old batteries finally go dead. The whole battery is loaded with sulfate by then. Sometimes a small bridge or steep pile of sulfate shorts the battery before it’s really old. Now don’t spit your coffee here….The fix is to remove the battery and slam it down on concrete right on the bottom. Do it a few times as hard as you think you can without breaking the case. Slam it nice and flat as to not catch a corner. This knocks loose sulfate down into the bottom where it is harmless. Want proof? Find a pile of dead batteries in the 10v range. Slam them then charge them. About 1 in 3 will charge right up and get you down the road. I ran batteries that I recycled like this for 35 years and never paid for car batteries. They often pile “bad” batteries on the side of repair shops. I take my meter and grab the best ones. Slam and charge and I’d have another free battery. If you have yours out then slam it for maintenance to knock the sulfates off of the plates. I slam every battery I have out of the vehicle to knock that crap to the bottom. Mine current battery is from 2016. That is ancient in this Phoenix AZ heat that I live in. Works well on optia batteries as well. Not on all but give me 3 or 4 “bad” Optia Batteries and I’ll have one back to 12.5V. Of course you have the nasty acid hazard if you break the case but those things are hard to break. Hold it 8” off the ground and pound it down on the ground 10 times. It fixes 30% of old dead batteries and chances are better on newer ones.