[racprops]

Originally Posted by Occasionally6

The following might be useful:

The Jaycar DFA is one of three similar units.

A Digital Pulse Adjuster - PWM signal in, altered PWM signal out with the PWM input frequency the same as the output.

An Independent Electronic Boost Controller - PWM signal in (intended to be injector pulse width), programmable PWM signal out with the PWM output frequency fixed at a constant, programmable, value.

The DPA - voltage in, altered voltage out with 0-1V, 0-5V and 0-12V ranges.

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

All three units require a Hand Controller unit to program them so the cost of that will have to be factored in. (One unit can do all three.)

I have two of these.

They are listed in Jaycar's back catalogue so should still be available, from Australia at least.

They do not have the DPA any more.

The kits were developed in conjunction with Silicon Chip magazine and descriptions of them - complete with how they work, circuit diagrams, full scale PCB images, schematics and assembly instructions - are available in book form in "Performance Electronics for Cars". (There are a number of other interesting/useful kits in that publication similarly described.)

Silicon Chip makes available, accessible from a link on the company's website, programmable PICs for projects that are described in the magazine. It's possible that the programmed PICs for these units are available that way i.e. it's possible the kits can be duplicated.

You won't be able to use the DPA to alter air:fuel ratios at part load by altering an air flow meter signal. That is because you can have high or low engine loads at less than full air flow and can't distinguish between them. You should be able to use an altered MAP signal voltage to do so, if you have speed-density based engine management. (I think the Ford 4.6 does not.)

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...

Using the DPA for introducing lean burn with an air flow meter, you would use the 0-1V range on the adjuster to change the O2 sensor voltage the ECU sees. That would only affect closed loop - by definition light load - air:fuel mixtures, so should be safe. Be careful though because the air:fuel ratios learned in closed loop may be extrapolated into high load open loop. You will also be limited to changes within the fault code error parameters of the ECU self learning.

It is the 1 to 5 volt range.

Consider that when used to alter the O2 sensor signal it is only the air:fuel ratio that can be altered, not the ignition timing. Altering a MAP or air flow meter signal will alter the ignition timing because it moves the engine load:rpm point on both ignition timing and fuel maps.

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

Rich