A slow response time from your oxygen sensor can cause the exact symptoms you
describe. Slow response can be caused by an oxygen sensor going bad, a dirty
oxygen sensor, recent exhaust system modifications, sensor relocation, fuel
additives, etc.
If you had an A/F gauge - you could see this behavior visually.
Hope this helps - Latr,
Shane
Paul Macey wrote:
> Subject line says it all. Yellow Check engine symbol came on upon startup
> last night after my truck sat in the hot parking lot at work, all day.
>
> Service dept reset the code on my 2001 4.7, said all should be fine but
> scheduled a tentative appt for 8/20 to check into it further (they allowed
> me to stop by today with no appt to check the code and clear it)
>
> I have a Robert Shaw GT755-180 t-stat and Jet Chip II that have been
> installed for at least a month. The temp gauge has and currently is, at
> the same reading since these installs, the truck's performance remains the
> same.
>
> The t-stat appears to be functioning normal, during startup, it runs
> smooth, same idle as always, and warms up to operating temp as it always
> has before...looks like it is not stuck open or remaining closed, right?
>
> Thoughts on my next step? Just drive the truck till 8/20 to see if the
> check engine light comes on again? Go under the covers and check the
> t-stat? Bring it for service w/o the Jet Chip and let them pull the t-stat
> and possibly charge me for that service? Allow them to re-install the
> stock 190 t-stat that I kept? Replace the 180 t-stat (are these GT755-180s
> bullet proof?). Call Jet Chip and describe the problem and ask for a new
> chip? Reset the PCM (I know this would have cleared the original code)
>
> I hate to have the service dept or me go under the covers if it can be
> avoided at all but I also don't want to cause any potential problems with
> the engine...just a quirk in the PCM code or temporary problem with the
> t-stat/chip?
>
> Anyone else have the same code and symptoms? If so, what was your final
> fix?
>
> Thanks in advance!
-- '96 IndyRam-HisIndy-MPI TB Pulleys RTcam MPComp HVoilpump DynaGearDoubleRoller WindageTray CompTAs '96 IndyRam-HerIndy-numbered(#142)"Track Truck" '74 Triple-Black Dodge Challenger Rallye 360 EFI R&D vehicle '93 Dakota CC 318 - soon to be mine 8)
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