I was reading through the boards tonite and came across this. Very interesting I though.

http://www.ws6.com/mod-7.htm

Seems that a lower fuel pressure came up with gains? Is this just on OBDII vehicles? Very, very interesting findings. Does anyone else run with a lower than stock fuel pressure? Can it be safe for driving daily? I am about to have a RaceTronix system installed. I reconsidered buying a A/FPR after reading this.

Thanks..

 

Did you read the NOTE? There is no power to be gained in the long term.

 

The only time I recommend buying an AFPR is if you're running nitrous and NEED the extra fuel pressure. Or, if your injectors are a little small and you need to get your injector duty cycle down. You have to have an good fuel system before you can really consider either one though. If you want the gain from leaning the motor out, get a custom tune (or dyno tune).

 

Its easier to just look at the pictures......

We've been pointing this "note" out for at least 6 years now, and no one ever bothers to read it.

 

For those whom dont know to scroll down...

NOTE: One thing that I have found after some time with this mod is that the stock computer is quite smart. After lowering fuel pressure to achieve a better air/fuel ratio, the computer sees this at part throttle and adds injector pulsewidth to compensate. Basically, horsepower fell back off to where I started from. While normal trains of thought tell us that since O2 values are not measured during wide open throttle, that fuel pressure should have a long lasting effect here. Actually, it does not. The computer uses the last known long term fuel trim integer at WOT, which is to add fuel since at part throttle it has adjusted for being too lean.

This mod is helpful for tuning the block learns to as close to 0% as possible, giving the computer the widest range of adjustment, but not for horsepower. For more horsepower, we need a computer program with a different target air/fuel ratio.

 

hope im not getting too far off track here.i have an 81 elco w/ 97LT1@T56.Working w/ 38lb.injectors @A.F.P.Reg.@dual exhaust w/2 high flow cats.otherwise the car @ computer are stock.what air/fuel ratio#should i shoot for when having P.C.M.reprogramed.can i also program 1 rear O2sensor passenger side. thanx

 

Ok, I'm trying to follow what you are asking. Are you wanting to know the target a/f for WOT? If so, I'd say 12.6-12.8 seems to be where the most power is made. I don't understand what you're asking regarding the O2 sensor. Also, @=at and &=and.

 

Sweetred95 sorry im a tilesetter{ i cant type worth a ****} i was just wondering if the p.c.m. could be programed using the 2 ea. 02 sensors up front [as always] but can i get away with running 1 ea. 02 sensor at the rear bank.i have an extended 02 wiring setup but when used the service engine light comes on.also thanx for the info on my F.P.R. thanx again

 

You can tune the rear O2's out, if that's what you're asking. If not, clarify a little more.