986 Forum - The Community for Porsche Boxster & Cayman Owners - View Single Post - Miss Fire on 1,2,3 and cut out at junctions.

mikefocke · 11-04-2010, 05:39 PM

as a highly unlikely cause. If it starts the car and the alternator is charging it, there is plenty of juice to fire the coils and the plugs. The size of the battery is important in cold starts, and slight differences in capacity don't matter other than those rare conditions. And a battery shouldn't run down over a week, mine goes several weeks between use and always has on 2 batteries, neither Porsche branded

Other than gas which has become bad over 9 months, what occurs to me is the car sat and the battery might have run down even though you occasionally started it and thus the ECU might have lost its settings. This is trivial except when the ECU was making an adaptation for a problem that existed before the battery lost its charge and the ECU its settings.

But for all the problems to be on one side of the engine is strange. If it were the battery or the gas, I'd expect random problems on both sides.

Without knowing the exact codes, I can't determine their seriousness. Not knowing that, I'd have the car put on the back of a flatbed truck and taken to the nearest real expert, someone who really understands the diagnosis of tough problems and has the equipment to do it.

11-04-2010, 05:39 PM	#3
mikefocke Registered User Join Date: Aug 2005 Location: Sanford NC Posts: 2,537	I view the battery as a highly unlikely cause. If it starts the car and the alternator is charging it, there is plenty of juice to fire the coils and the plugs. The size of the battery is important in cold starts, and slight differences in capacity don't matter other than those rare conditions. And a battery shouldn't run down over a week, mine goes several weeks between use and always has on 2 batteries, neither Porsche branded Other than gas which has become bad over 9 months, what occurs to me is the car sat and the battery might have run down even though you occasionally started it and thus the ECU might have lost its settings. This is trivial except when the ECU was making an adaptation for a problem that existed before the battery lost its charge and the ECU its settings. But for all the problems to be on one side of the engine is strange. If it were the battery or the gas, I'd expect random problems on both sides. Without knowing the exact codes, I can't determine their seriousness. Not knowing that, I'd have the car put on the back of a flatbed truck and taken to the nearest real expert, someone who really understands the diagnosis of tough problems and has the equipment to do it.