What should the A/F ratio be for a KB 5.4 under part throttle boost? Right now when I am on the interstate in OD doing about 70, I can push the pedal down about 1/2 without downshifting and hit 6-7psi at 2300rpms or so and my autometer wideband is showing 14.7:1. When I get on the throttle hard almost wot (75% down to WOT) it goes 12:1. I am experiencing a slight tip in detonation when I hammer it on the interstate but that is it. I am thinking it needs to richen up sooner but wanted some input on the matter. Truck has no FMU and 42lb fuel injectors running 10psi with water injection.

 

Wow even the 12:1 at WOT seems lean. High 10's or 11's would be my preference. But about your question. Maintaining 14:7 up to half throttle is normally ok but if your knocking then theres a problem. Your gas may contain up to 10% ethanol which our a/f meters are not calibrated for. So 14:7 could be 15.0 or even worse 12:1 could be 12:4 which quite frankly IMO is down right dangerous. What fuel pressure are you running and what pump or pumps?

 

Don't have a fuel pressure gauge hooked up. I have a 255l/hr BBK in tank pump and a boost a pump.12.1 is the highest I have seen the second I hit boost under WOT. Most of the time at full WOT it ranges from 10.9 to 11.5. Gas does have ethanol.

 

What percent of throttle input is it supposed to go to open loop?

 

There are a couple of triggers for open loop, both of which could be changed in your tune. One is based on throttle position, the other is based on load. There are also delay settings to keep the engine from going open loop once the set point has been reached. You can datalog to see when your truck is going open loop by monitoring the open and closed loop switches.

 

Can your AF ratio gauge be calibrated for the ethanol? When Troyer tuned my truck for 10% the new stoich became 14.2 and I was able to set me innovate XD16 to read 14.2 for stoich.

 

i would say high 10's is to rich, mid 11's to low 12.1 is where it should be for wot. Anything lower your just not running efficiently.

 

I would love high 11's and low 12's and when I was running 8psi thats where she was. But now running 10psi it dips down to the high 10's and works back into the 11's. Considering the varying quality of fuels available i'm thinking better safe than sorry. I guess as long as there is not a puff of black out the pipes its not to rich lol.

 

I my self am 9-10lbs of boost and i run normally 11.8-12.0. And im on ****ty 91 octane. I think if your tuning tunes correctly for the octane and keeps timing where it needs to be you should be fine with that a/f. Do you feel any dips in power being that sometimes you hit 10's?