'95 Legacy running rough on cold start...

[Hallraker]

A couple weeks ago my '95 Legacy (EJ22) began running rough on a cold start,
but only after sitting for at least 24 hours. Driving it daily seems to
prevent this, but sitting over the weekend is enough time to trigger the
rough running. Idling isn't too rough, but giving it gas to leave the
driveway causes sputtering and stumbling. If I back off the throttle it
eases up, but opening it up causes it to worsen and a misfire code to
appear. The entire problem just goes away once my engine reaches operating
temperature, but it's back the next day or the day after.

Any ideas? Never seen this before, but then again all my previous vehicles
would just stop running completely instead of at least trying to run.

-Matt

 

[John]

Do you have much dew/condensation when this happens? Could be time to
replace the wires.
What other tune-up stuff has been done?

 

[Carl 1 Lucky Texan]

sounds fuel/air related or possibly timing. Since many electrical
problems are worse when heated - and yours is opposite - I'm gonna
suggest possible engine temp sensor (NOT coolant temp) (or its wiring).
For some reason it may not be telling the CPU to 'choke' on startup. And
when the engine is warmed up - well it runs at its normal 'lean'
condition. I think this is also one of the sensors that won't throw a
specific code.

I dunno

Carl