closed loop to forced open loop idea

[bmantis]

A lot of people going the piggyback route are having issues trying to over tune their closed loop settings. I think most of us have realized that there is no tuning the closed loop. We would still like the closed loop for lower rpm fuel economy, but don't want to boost with an afr of 14.8. Here is something I was thinking about, and tell me what you think.

Why not just put a pressure switch inline with your 02 sensor. Set it for a low psi. Whenever the car went over your set psi it would disconnect the 02 forcing the ECU into open loop.

[zcgod]

or you can get a aem or even a safc2 and tune the fuel accordingly so when you hit the throttle to the preset percentage it flips to the boost map and you can boost away and when you get below that point it goes back into other map. far safer than jerry rigging shit to blow your investment up

[bmantis]

The SAFC won't change the fact that you are in closed loop. You can increase the fuel all day long, and until it pushes it past the point that the ECU can correct it won't change anything. By the time it's gone this far you've probably thrown off your timing along with your short and long term fuel maps as well.

I was thinking about this a little more, and I was wondering if it would switch over quick enough anyway. I'm thinking it may take too long after it was cut for it to switch to closed loop which would cause some issues with trying this.

I don't think we'd be where we are in making NA-Ts perform the way they do without the "jerry rigging" that we've come up with thus far.

[zcgod]

when you switch from closed and open loop it sends a check engine code also if you show coolant temp high, air temp high and exhaust temp afr low so it can "compinsate" it will technically work but with the timing retarding and not advancing like you need, it will be a negative effect. you can na-t anything, they do it all day long but those who do it right get to have a running car the next day

[DrNick]

Why not just put a pressure switch inline with your 02 sensor. Set it for a low psi. Whenever the car went over your set psi it would disconnect the 02 forcing the ECU into open loop.

Its a nice idea but not neccessary. You are trying to fix the symptom and not the actual problem. Closed loop operation only occurs on part throttle/low load driving. Under WOT runs the car is ALWAYS in open loop.

If you are boosting an NA car you will no doubt be in the high load portions of the stock map and will be in open loop anyway.

The area of your mapping that you need to consider is the cruise and low load areas and unfortunately without a management system that takes full control of fuelling it is next to impossible to get the tune perfect.

[bmantis]

I have always had my car forced into open loop 100% of the time with the o2 removed. Only recently did I try running the car in closed loop again, and I was loving the fuel economy for driving around town. With my V8 maf and 440 injectors the ECU can handle keeping the car at 14.8 without me having to touch the safc at low rpms. It's just that there's the grey area of boost on leaner afrs when you don't necessarily have WOT. I was trying to think of a guarantee that it would be forced into open loop. For now I just have the o2 unplugged again and running open loop all the time.

[domantas]

its a pain isint it...