2006
987.1
will not Idle after Dead Battery
My
2006 Cayman S
got a dead battery the other day, I needed to leave and have a long downhill driveway so I figured I would try and roll start it since it had power still, just not quite enough juice to start, when I dropped the clutch it sounded like the engine started and then the car died and came to a stop suddenly with a puff of black smoke from the exhaust. And when I charge and attempt to start the car, it will crank like normal, fire and them immediately die
Doing initial research I believed the ecu forgot how to idle and could not run anymore so I needed to do an idle re-learn routine, this did nothing so the
next
plan I had was to pull the intake and clean the throttle body since some said as the ecu adjusts for a dirty throttle body, when it resets it may struggle to stay running so I cleaned the throttle body and noticed a lot of oil on the inside so I replaced the AOS while I was in there since I read the puff of black smoke could be a symptom of that going bad and it was going to need replaced someday anyway so might as well right?
Even with a new AGM battery with 850 CCA, clean throttle body and a new AOS and after a few idle relearns the car still will not stay idling, at this point, my only thought is something with the fuel system, but if it isn’t getting fuel it shouldn’t fire at all right ? the car has a full tank of 93 octane gas about 2 weeks old
Any ideas or knowledge on the subject is greatly appreciated
You possibly experienced a low enough voltage condition, trying to bump start it on a dead battery that you either damaged the ECU or the ECU has forgotten it's fuel trims and they're off to some crazy number.
If you have a
Porsche
diagnostics tool, scan the system. There will be codes. If you see a lot referring to "Terminal 15" errors - that's a low voltage thing. Clear errors and try starting. If it still doesn't idle correctly, use your tool to reset the ECU to default parameters, or if your tool will do it - do a "Vehicle Handover" reset of everything on the car.
It's almost certain to be an issue caused by a low voltage condition. Once it's running I'd suggest getting a jump pack and keeping it handy if this sort of thing happens again.
Oh - welcome to
Planet-9, the Friendly Porsche Forum
for owners who remember the good old days (bump starting.. haven't done that in 25 years or so..)
Once you get it running correctly take some pictures of it in scenic environments and make an intro post in the New Member Introduction section of the forum.
Good luck! Let us know how it works out.
Don,
Very well written and I'm certain others will benefit from this in the future. I already did!
