Dan Kramarsky wrote:
> Rascal & Biff,
>
> The plugs, cap, rotor and wires were all replaced in March 2005. ( i did a tune-up )
>
>
> It ran fine all summer. The rough operation between 1400 and 2000 RPM appeared about 3
> to 4 weeks ago.
>
> I guess something could be failing. I think it could be O2 sensor. TPS and MAP check
> out ok. The coolant temp sensor is flakey but thats just for the gauge in the dash
> right?
>
>
> I will check the resistance in plug wires. You said anything less than 14,000 ohms
> right? But typically its 4,700 ohms. My wires are AutoLite Pro.
>
> Also I will get another set of AP3924 plugs and gap at 0.035 just to see if theres any
> difference in performance.
>
> Q: What about a valvetrain problem? Would it show up in certain bands of RPMs. Say
> 1400 to 2000?
Seriously doubt its an oxygen sensor. You can unplug that sensor and
remove it and the truck is still going to start and it shouldn't run rough.
o2 sensors don't start to feed input to the ECM until after it gets to
operating temperature. Until then its running off the preprogrammed
fuel/ignition/timing data. Yes I suppose it is *possible* a bad o2
sensor could cause it to run rough.... but if it does the rough running
after a cold start, as well as after its warmed up - then I would say
its is not an O2 at all.
Burnt valve, cracked head, or bad head/intake gaskets can cause that,
but as to if it will show up in certain RPM ranges rather than others -
- can't say for sure.
How did you check the TPS and MAP sensors??
-- --------------------------------------------------------------------------------------- Rocks are for skipping... I'm all about the mud http://members.aol.com/silvereightynine/ AIM & Yahoo: SilverEightynine
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