All 6 cylinders misfire
 

First off, I just bought my first Boxster, 2004 Base 65,000 miles, a week ago and love it. Secondly, I appreciate all the information available on this site as well as Mike Focke's page, they have helped me out greatly.

Yesterday my check engine light came on and has stayed on(not blinking). I went by Autozone and they pulled the codes for me. All 6 cylinders had misfired. I can understand 3 misfiring, but all 6? The CEL came on about 45 minutes after I got some gas (used highest grade). Any ideas? I know nothing about engines.

Thanks in advance.

A couple of questions....

1) Did you feel the engine misfire or just see the CEL illuminate?

2) When Autozone read the codes, were there any other codes listed apart from the 6 ignition missfires?

3) Did Autozone re-set the CEL and has it returned ?

4) How does the car drive - is it running OK now?

The secret is the complete list of CEL codes that Autozone read off - if you can post them it will give a better understanding of the problem.

Thanks Steve.

1) I did not feel the misfire only saw the CEL on the dash. I was traveling on the highway at the time of the CEL, going about 65-70 mph.

2) 7 total codes: p0300-p0306

3) Although he did not say he reset it, the CEL was gone when I left Autozone. It has not come back on, but I haven't driven it very much due to my concerns.

4) Seems to be running fine. Sounds normal on ignition and shifts smoothly.


Can "bad" gas cause this to happen?

If you had bad fuel.you would still be having fault codes and missfires...
I would drive it locally over a few heat cycles (up to full temp and back to full cool mode) and see how she goes.
Isolated glitches are not unknown, but......

I'll give that a try and report back. Thanks.

The ECM detects engine misfire by monitoring the crankshaft speed and detecting variations/fluctuations in the speed. Engine misfire usually results in incomplete fuel burn. This rich condition can result in increased emissions and possible damage to the cat's, and thus, the CEL is illuminated.

Misfire across all 6 cyls generally rules out individual cyl components like spark plugs or coil packs and instead points to a component that is common to all cyls.

The usual likely suspects are the MAF or pre-cat O2 sensors but could be anything from a loose gas cap to a bad coolent temp sensor.

Drive it and see if the CEL returns.

"could be anything from a loose gas cap"

Obviously, this is what I hope caused it. I filled up about 30 to 45 minutes before I noticed the CEL. Could have come on soon after I got gas and I didn't notice.

Thanks for the help.

UPDATE:3 days of driving and no CEL. Keeping fingers crossed.