Well, I imagine the PCM probably uses the EBP sensor only if the EBPV is not disconnected. I know when back pressure goes up, boost goes to zero. PCM has to fuel differently with zero boost to keep the truck moving. Of course its main purpose (EBP sensor) is to inform the PCM how much back pressure is present so it can make informative decisions controlling the EBPV. Also the PCM limits back pressure to 43PSI maximum.

I could see where the 29 fuel tables Bob mentioned are in play when the EBPV is in operation, such as on those freezing mornings. However that is just a guess on my part. It is interesting if you subtract 43PSI from 29 you get 14, sea level atmospheric pressure. So heck, who knows, maybe for every 1 PSI back pressure a different fuel table is used. Generally, on my truck, back pressure varies from 14PSI at idle to 17PSI cruising. I seldom see anything above 17PSI unless EBPV is operating then all bets are off. It then varies anywhere between 20PSI and 43PSI, depending on engine demand and my foot.

 

Good info Jim.