Gas mileage and headers

[Marteney, Steven J.]

That's the thing that's driving me crazy!!!  I would expect more pedal input
to show up as more TPS voltage (at the same rpm and gearing) or as higher
MAF reading or more fuel shown as a higher BLM.  But it doesn't.  The block
learn multipler is lower, the reported pulsewidth is the same, the MAF
reading is the same.  (Of course, by "same" I mean there is some high
frequency variation between Diacom frames but they are generally averaging
about the same.)  Back a couple of months ago when I was doing minor chip
tuning for the highway I was bumping up the timing in individual cells and
could see the BLM, MAF reading, and pulsewidth go down for the same rpm and
cruise speed.  Now, the only Diacom parameter that changed is IAC counts
went up 10, and coolant and intake air temps went down 5 to 10degF.  I
mentioned the timing change previously.  Maybe that's it.  Seems
counter-intuitive to me, but I'm probably just thinking too hard.  I'll keep
working on it.

Thanks again for tolerating the out-loud thinking!
Steve

>As far as the mpg going down after header install, it could be the oxy
>fuel, or it just could be the fact that you torque curve has been shifted.
>Depending on the design of the header, you can lose bottom end torque, and
>with OD at highway speeds, your operating in that range.  Less torque
>requires more pedal input and more gas.
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