Wont stay running - 986 Forum - The Community for Porsche Boxster & Cayman Owners

thstone · 07-28-2011, 06:31 PM

Everyone seems on the right track - seems to be fuel/air related. Another component to consider would be the fuel pump.

Lordblood · 07-28-2011, 09:33 PM

I've had this problem on my previous Boxster. It was not the MAF in my case, I personally wouldn't start there. My car had a vacuum leak at the time but even after fixing it the car kept dying right after startup.

SF-Rockster · 07-29-2011, 01:09 AM

Quote:

Originally Posted by Lordblood

I've had this problem on my previous Boxster. It was not the MAF in my case, I personally wouldn't start there. My car had a vacuum leak at the time but even after fixing it the car kept dying right after startup.

So.. what was the problem?
How did you fix it?

Dale_K · 07-29-2011, 01:19 PM

I've filled my tank so high that gas ran out on the ground and didn't get a CEL.

Lordblood · 07-29-2011, 07:16 PM

Quote:

Originally Posted by SF-Rockster

So.. what was the problem?
How did you fix it?

Simple fix, I rear ended someone when I was sick and not paying attention to the road. It racked up about 12000 dollars in repairs so it was bought out by the insurance. In other words, I have no idea what actually caused it.

bronx · 08-01-2011, 05:45 PM

Update

Didn't find any vac leaks, replaced the sparks and air filter while I was there- wasnt sure the last time they were replaced, all looked fine. Didnt fix the problem.

Unplugged the MAF sensor and idle smoothed out, stayed running and did not miss when given gas. Problem solved, right?

No. replaced the MAF sensor and still the same issue. Starts evey now and again, idles rough when she does, pops and stalls if given gas. Unplug the new sensor and she starts right up, idles fine, and revs when given gas.

What next?

bronx · 08-01-2011, 07:03 PM

Played with it some more and problem is there with and without the MAF sensor plugged in, seems better with sensor unplugged- starts more often, idles smoother, revs if gentle with gas. Still no CEL or codes. Maybe I should roll it over a cliff.

Dale_K · 08-02-2011, 12:12 PM

Did you disconnect the battery? I think the computer needs to relearn the fuel trims with a new MAF. Reseting a CEL also forces a relearn I found out. Also there is a e-throttle learn/calibration that you perform after reconnecting the battery by turning the key on and waiting 60 seconds, then removing the key. It's doubtful these are going to help you very much but you should probably try them anyway.

A new MAF fixed my problems. You could buy a Durametric and examine the fuel adaptation readings and the MAF readings. My MAF readings looked good and fuel trims were out of wack but a new MAF brought the fuel trims back to nearly perfect.