Gas mileage and headers

[Bob Valentine]

Hmmm....  higher IAC counts = more air past throttle blades.  

Still can't understand why that wouldn't show up in the MAF reading, but
then I've never done any MAF tuning.

-> Bob


At 11:50 AM 10/26/2000 -0400, you wrote:
>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.
>----------------------------------------------------------------------------
>To unsubscribe from gmecm, send "unsubscribe gmecm" (without the quotes)
>in the body of a message (not the subject) to majordomo at lists.diy-efi.org
>
>
----------------------------------------------------------------------------
To unsubscribe from gmecm, send "unsubscribe gmecm" (without the quotes)
in the body of a message (not the subject) to majordomo at lists.diy-efi.org