North American Turbocoupe Organization

Manual Boost controller/EEC question
Eagle11401 Offline
Another post got me thinking of this: Right now I'm installing a Gillis in my 86XR7 and got to thinking, with the BCS boost is 15, 15, 10, 10, 10, if I bypass the bcs and just have it set at say 15psi, then its 15psi in every gear right, so how would the computer view this? Wouldn't the computer only let the injectors supply enough fuel for 10psi after 2nd gear causing the car to run lean? How is timing affected? Anybody deal with this?
87 Turbo Coupe -> gone

Pete D Offline
To the extent that the VAM can measure air flow, fuel metering is tied to air flow. The engine is flowing (approx) as much air at 15 psi in first as in 3rd or 4th. Notice I said approx. The EEC tables are built to richen at and above 3K and even more so at WOT.

Consider; the EEC doesn't know what actual boost, in PSI, is. It only knows what gears it is to allow high boost (more than 10) and what gears is only allows 10. The EEC doesn't actually know if boost got that level or not or if it went higher.

More info here:
Pete Dunham


Matt S Offline
Posting Freak
Under stoich (closed) loop the O2 sensor makes up the difference. Under WOT, pre-programmed fuel maps determine fuel flow. This is why some of us run higher than stock base fuel pressure; to compensate for the extra air we are blowing.
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