johndeere185

What are the pros/cons of running open loop all the time? Seems like my truck runs so much better when I force open loop. Anyone run this way?

JohnnyLightning

There is nothing wrong with running it in open loops just as long as you adjust your A/f properly...JL

johndeere185

hm ok thanks JL, ive heard yes and no, but it runs so much better open loop... So I believe im going to fine tune my a/f and leave it like this. So are the o2's off in open loop? If so ill pull them out and put a plug so they dont foul.

Rob54

I run mine in open loop above 1050 rpm. I have the idle in closed loop, with a slight lean bias. For me it makes the idle very consistent, IME the afr will vary slightly in open loop depending on atmospheric conditions, but not enough to be a problem. You will probably pay a mileage penalty, but I find the throttle response to be superior.

__________________
2001 F-150 S.Cab XLT Lightning conversion @ 17psi, JLP L/Block, stage3 cams, KB 2.3, JLP upper, Accufab TB, SCT BA2600 in 110mm tube, JLP Ram Air, Complete custom Aeromotive fuel system w/ A1000, NX wet shot, Snow Meth., Afco D/P heat exchanger, MAD elec. fan, JLP Bassani R exhaust, PI 2800 stall, LenTech 4R70W, 3:73 gear, True-trac, Metco Bars, 3/4 drop on Niche Throttle 20's, tuned by me with SCT PRP, and Innovate W/B. 11.30 @ 125(1/4) 7.28 @ 96(1/8) , 5250lbs. 706/778

johndeere185

Yeah I seem to have much better throttle response, and I really like the idle, I can actually hear the cams

rhynotune

I've done it both ways. If you take the time to tune your closed loop the right way, tweak all 30 points of the curve until they're right with the short terms turned off, then an open loop and a closed loop tune should run identical with the closed actually running better.

The biggest problem I have/see is the transition between open and closed, the idle hunting, and overall throttle response. What I've been doing is setting the fuel tables to 14.7 everywhere, and tuning and finding spots to hit every part of that cell in terms of load/rpm. Once I do that, I set the VE table perfect pretty much the same way. I like having the fuel pump jumped to high side 24/7 then I turn closed back on and the trucks run really good.

JohnnyLightning

you will not suffer fuel economy IF you tune your maf correctly..ive tuned hundreds of vehicles and i don't care what anybody says their are some set-ups you'll have to tune it in OL and call it a day.because once you put it back in CL you'll still have issues..this is usally on heavy modified and big cam motors..Not ALL but i believe out of the hundreds i have tuned i might have done like 4 in OL...also remember to data log the idle intregator and tune it properly as well...Good Luck JL

johndeere185

thanks guys, I just spent several hours tuning the a/f from idle to wide open, at full and part throttle, ive almost got the a/f correct everywhere and it runs much better, smoother, and a LOT stronger.

johndeere185

so are the o2 sensors still used, or can I take them out?

rhynotune

You can remove them.

johndeere185

This morning it was about 40* when I left for work, as soon as I hit the pedal, it died, and wouldnt stay running no matter how many times I tried starting it. It was pooring black smoke, so I figured it was pig rich from the cold. Im sure there is a setting for adjusting this, What needs changed?

JohnnyLightning

Thats not the problem you have a mass air connection problem or something like that check al your vacum lines and connectors...or you did not calibrate the maf correctly...JL

johndeere185

I believe my maf is calibrated correctly. Last night I spent hours on it and I got the a/f to almost exactly where I wanted it. I guess I'll see what it does tomorrow morning. Also, My a/f in 3rd gear at WOT is 11.4-11.9. in 2nd, at the same maf counts, its 12.2-12.7... How do you adjust this? By making 2nd gear WOT a/f correct, it makes 3rd incorrect. Seems like more of a load, the more rich.

lvgolfer962

that happend to me last week. truck died, barley get it started, limping back home it was blowing black smoke like a diesel. mine was not a tune issue, the maf came apart.

FAST-EDDIE

Im in the process of building a new built long block but my old engine was a built long block all the supporting mods 2.3whipple full exhaust built tranny and my truck has all ways been tuned in open loop and it drove like a stock truck until it you lay on the matt