[Occasionally6]

Originally Posted by racprops

I have two of each of these, I don't have the boost Controller..

Bought as kits or assembled? The instructions in the kits are photocopies of the relevant chapter from "Performance Electronics for Cars", providing the detail on how they work. I don't know what comes/came with the assembled items.

They do not have the DPA any more.

Apologies for my typos - where I typed "DPA" above I meant DFA - Digital Fuel Adjuster. Assuming you meant the same, there is what appears to be an updated version, now called "Voltage Interceptor for Cars with ECUs" for which PCB artwork and software is being made available:

Programmed Micros - Silicon Chip Shop - Silicon Chip Online

I haven't looked to see if there is a full kit form for sale anywhere.

While I don't have immediate access to those issues of SC in which it was described, I can access them if you have questions about that device that you would like answered before spending money on a subscription, the PCB or software.

The Ford has a voltage changing MAF. Range is 1 to 5 volts.

Here I would like more info. That is what they said it was for and I can seemly cause the A/F Ratios to change BUT the fuel trims seem to correct for it by adding fuel YET the A/F ratios stay lean...

The engine will draw through the air flow meter the same mass of air for a range of engine loads i.e. inlet manifold pressures. It depends on the engine speed that a particular air flow occurs at.

At low manifold pressures, high rpm, you could safely lean out the air:fuel ratios. At high manifold pressures, low rpm - with the same air flow rate - you may run into detonation with an air:fuel ratio leaned out by the same amount. With a single dimensional interceptor, like DFA, you are unable to make the distinction.

With closed loop fuel control, you will have to go further in order to reach the limits of the closed loop correction. That may result in even leaner air:fuel ratios at high manifold pressures, when you do get into open loop, or a fault code default to an open loop, rich (safe) air:fuel ratio map in place of closed loop control. It depends on what the ECU does to correct against the changes being made and where it sees a fault.

I think the original intention of the DFA was to bring back the air:fuel ratios to something resembling the factory functionality after changes like altered valve timing (cam swaps), larger injectors or air flow meters. It probably works OK to do that.

Here an interceptor, like the Apexi AFC, with two - rpm and TPS - dimensional inputs may be superior. That allows a distinction to be made between low and high manifold pressures i.e. engine load. If I understand it correctly, it overlays an n-alpha mesh over the existing engine management maps and allows the amount of correction to be adjusted independently within each cell (16 load points = 4x4?) of the mesh. Perhaps iveyjh would like to comment on this. You will still have to deal with the closed loop and O2 sensors.

It is the 1 to 5 volt range.

For the O2 sensor? That would be unusual for a narrow band sensor but OK. If it is not narrow band, that changes the whole thing.

I also have devices that will change the O2 response...

Rich

And you have 4 of them right? From experience, it can be tricky to emulate O2 sensor signals. I think it's because the ECU looks for the response to changes it has made and not just a signal that "looks" to be right.