About 10 days ago I took my Jimmy out for a spin. Everything was ok.
I stopped and put about 10 gas in; about 20 minutes later the Service
Engine Soon light came on. I stopped at a service station, at which
time the thing idled rough as hell. My first thought was water in the
gas (from sitting, perhaps from the station I bought gas at [Tessoro])
so I put in a de-icer additive. The condition persisted throughout my
80 mile trip - rough idle, ran ok at higher RPM.
This morning, after learning how to obtain the error codes, I started
it up. Same condition, rough idle, smooth at higher RPMs. After
letting it warm up (about 15 minutes), the idle smoothed out and the
Service Engine light went out. I went ahead to get the error codes:
32 (EGR) and 34 (MAPS). I then started it back up, Service Engine
Soon light stayed off, idle remained smooth. I took it for a 5 mi
test drive, got home and it remained smooth idle, light out.
Is it possible for water / ice in the fuel /
fuel lines to cause this
condition and throw these errors? What else would cause these
symptoms and error codes, that would just "go away"? I am still
thinking water in the fuel.
The vehicle is 94 Jimmy 4.3L V-6 Vortex series W
Thanks for your thoughts/opinions.