My R53 with 50,000 exactly acted up this cold morning.

It's 24 f this morning and it stumbled and stalled with a CEL P0303 that won't reset. I just drove to the store and it runs smooth and perfect.

This is the first time it has been out in the cold. The first owner never drove it past September.

The fault keeps coming back, but has no symptoms besides the light, runs great up to temp no fluid loss, I did plugs 10,000 miles ago. I am low on gas and parked nose down in my driveway.

I'll pull the plug etc when I get home, but again, it's all smooth and quiet

 

Check the plug torque again, 25 ft lbs (some people add a bit more to keep them from backing out).

Check the electrode connections on the coil pack for rust, the electrode for cylinder 3 is notorious for rusting and causing issues.

Is the car an automatic? Some auto cars require a quality scan tool to clear the codes in the trans control module as well, as they can become trapped in there and keep an error light illuminated, or keep the fault from clearing.

 

I'll check those today, no, it's a 6mt.

Good info

 

Just a thought, did you use anti-sieze on your plugs? Porsche has a bulletin to advise against using such things on plugs. The bulletin applies retroactively to all models and the theory is that the anti-seize tends to act as an electrical insulator between the plug and the cylinder head. This could have detrimental effect on the firing of the spark due to the loss of a good, consistent ground connection. Keeping those findings in mind, we make the same recommendations for the MINI, don't use anti-seize compound on the spark plugs.

 

No, actually after I put them in, I was thinking I should have used it, but now I'm glad I did not.

I did put them in a month or so before I did my 17% Alta pulley, but I don't drive hard, should I have done the one step colder plugs at all?

 

For an R53 with a pulley - NGK BKR7EQUP (4285) plugs HERE are recommended.

 

They are already in, but should I have, as I I really don't push it 95% of the time, I don't want them fouling from my grandma driving style

 

I GOT IT!

I first pulled the negative battery for 30 minutes, CEL still there.

Did DME reset, still there (I'm checking codes, erasing and starting after each idea)

Checked coil pack terminal #3 shiny as new, scuffed, CEL still there

Checked torque, 26 ft/lbs, still there.

Pulled plugs, cleaned with carb cleaner and torqued to 30 ft/lbs. Now for some reason getting P0303 and misfire with low fuel, I have 3/4 tank!

But, it reset and stayed away.

Why? I dunno.

But it's gone

 

How's your air filter? I have a 750il - V12 - I had a misfire on cyl 12 (P0312) - it was a filter housing full of acorns on that side. Clean filter, never saw the code again.

 

Practically new, M7 intake and filter 15,000 miles.