Starts up fine when cold, stalls when hot

DAVID SR.

MEMBER
2000 MITSUBISHI GALANT
6 CYL
FWD
AUTOMATIC
63,000 MILES

I received a service engine light and scanned an error code describing downstream o2 sensor on rear head. I disconnected the negative side of the battery has instructed in the manual and then proceeded to remove the 02 sensor on the muffler side of the catalytic converter. Not much room to work with but success.

I then proceeded to change the oil while I had the car jacked up along with the oil filter, no issues.

Then I reconnected the neg side of battery and started up the car. Car started up just fine and no more service engine light. I let it run for a few minutes to warm up and then turned the engine off.

I had the car parked near the garage door and needed to close the door. I jumped in the car and the car started up and then died. Subsequent startups are the same has long as the engine is warm. If I wait for about 20 minutes it will start up and run like normal until it gets warm again.

Also please note there is no service engine light at this time.

5 Replies

RACEFAN966

MECHANIC
5,029 POSTS

Ok so when it dies do you loose spark or fuel? Have you checked either when it dies to see which is missing? Thanks and get back to me and let me know what is going on.

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Tuesday, December 9th, 2008 AT 11:41 PM

DAVID SR.

MEMBER
4 POSTS

Spark and fule is good. If I give it a little gas after the restart when the engine is warm I can keep it running by stepping on the gas to keep up the RPMs. Its when I take my foot off the accelerator it dies. Seems to be an idle issue.

I read somewhere maybe in Carpros forum or another info website that if I disconnect the battery again and just let it idle without accelerating or going through the gears the computer will reset the idle as it goes through the warm up cycle.

Well believe it or not when I got home I disconnected the neg. Side of the battery and let the car sit for about 10 minutes.
Then I reconnected the battery and restarted the car without touching the accelerator and just let it warm up. I let it run/warm up for about 20 minutes, turned off the car and attempted to restart with success. I did it again, and again no problems.

I will keep you posted over the next couple of days to be sure and determine its not a fluke.