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p0300 codes: symptoms of a histrionic Porsche

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Well, it happened again. . .Posted this in Jan:

>>Left town for a couple weeks, '99 Boxster c 120K miles exposed to a cold Midwestern chill in my absence. When I came back, car started up immediately, ran fine for 5 mins. Then I lost a cylinder: clunky vibration when accelerating, lost some power, smelled gas, engine sound with a deep cough. Check engine light came on resulting in OBD code 0306 among others, though the codes seemed to fluctuate at times. 0306 came up the most consistently. Leaving the car alone for a few days resulted in a repeat of the phenomenon: normal engine function for a few minutes, followed by all symptoms of cylinder loss. . .<<

Readers will remember that it was just a plug/coil issue. Cheap fix.

Similar story today, though: went away for 5 days, came back and car sputtered and coughed. . .gave it a bit of gas, gradually got some power, but engine still with unhealthy growl, smell of gas: misfire. CEL on, varying between blink and steady. Same deal, different cylinders: OBD II codes were p0300, p0302, p0305.

At least I knew not to freak. I appreciated this awesome bit of wisdom from Loren:

>All cylinders misfiring has to come down to one of the following:

wrong spark plugs

bad gas, plugged fuel filter, or fuel pressure too low

air intake leak<

I'll try some new gas, check/replace the plugs and coils again, see what happens.

My question is this: why is my Boxster so temperamental? Shouldn't I be able to leave this jealous ol' gal for a few days of vacation with my wife without having to deal with a Porsche-style tantrum? Just not driving the **** thing for a few days seems to always result in some kind of problem. But I can leave my emotionally secure Subaru in the rain, snow, sleet, and hail for weeks, no problem. Seriously though, what is it with Porsche that such a well-engineered machine can't tolerate a few days off? And I mean literally 4-5 days?


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If it turns out that you indeed have bum coil again after just a few weeks (months, whatever), you'd have to be remarkably unlucky. I'd think that the coil failures are symptoms of something upstream.

As to your larger question, same deal . You may even have something even more systemic. The cars are usually lots of fun when they don't blow up. You might want to Identify all the exact conditions that are present when it craps out. Then follow them to a logical conclusion. You have already mentioned two. You said it "can't tolerate a few days off... literally 4-5 days?" . There's a condition and there is a solution. What happens in 4-5 days? Your battery can take a hit for one, (so what might that do), fluids settle, squirrels start messing around in the engine bay? etc. etc.

"ran fine for 5 mins." Another solid condition. What happened then? The engine is probably fairly warmed up, things expand and shift a bit...(maybe a couple of frayed wires move, touch and short...what does it effect.). Your motor has made numerous electromechanical adjustments to fuel and Air and who knows what else in f mins.. Maybe one of those electromechanical do-dads trips it's mechanism the wrong way into something else...

Guess what I'm saying is, from what you say, all your repairs may just be treating symptoms not curing the real problem. When you fix the real problem, life will be grand. And as far as German engineering, BMW & Porsche's are blast so they're doing something right, but some stuff is mind boggling, ridiculously bad.

Regards, PK

Edited by pk2
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