How to drive an injector

[Mos]

The hold portion of the peak and hold waveform on the JDM 4AGE ECU was pulsed, rather than linear current reduction (ie lower voltage across the injector). The injector doesn't care, it will only see the effective power which is reduced in contrast to the peak period which is full voltage, allowing full current draw. I don't know what other ECUs use for their hold period, but the Silicon Chip peak and hold adaptor assumed pulsed.

I suspect the DFA et al may try to trigger off all of the edges on the pulsed hold time and cause havoc.

The peak and hold adaptor is basically a low pass filter (to "see" what the injector sees, rather than what the ECU is supplying - ie the effective lower power rather than all the pulses), and a schmitt trigger. It does it in a funny way, by looking at the current through the injector and not the voltage on it.

So... I'd agree with Owen - low popularity and reduction of component cost.

Karl - I have yet to build a kit that hasn't been modified in any way

Gen3 1G Peak and Hold ? No idea Do you have access to a scope?

Mos.

[o_man_ra23]

op amp and capacitor circuit can be quite effective as a LPF, and very cheap to make... Just need to work out the pulse frequency (and if the pulse frequency is constant, if not its frequency range) and make sure it doesnt overlap the frequency of the injector pulse.

Damn these tight arses.

Cheers, Owen

[mic*]

Owen, thanx heaps for everything so far. I would tend to think you are right about the minimal design capacity of the kit.

Karl, thanx for the tip about the crystals. At the moment they are just resting on the board. Do you have tape/glue under that 20MHz crystal? Very neat. How does your optional link setup change the operation of the unit from default? Whats going on with link 1? Looks open?

Ben, I have the mag with colour photo's. Glad i did buy it tho for your exact reason. As a tip, whenever you build boards, do the links first. So you dont miss any coz they are so easy to leave out...

Cheers to anyone i missed. I am learning so much here...

[mic*]

Need some help please....

I have installed the DPA with peak hold adaptor. The adaptor taps the +12V feed wire to any injector.

I intercepted an injector finding red wire and a black striped wire. I pulled the clip off the injector and with the ignition to ON found +12V at the red wire. I didnt even check the black wire after that. Silly me.

Anyway, shit doesnt seems to be working 100% now and i went back to this for some reason.

Anyway, I have +12V at BOTH wires of the DISCONNECTED injector clip with the key turned to ON. I did not think that the ECU held +12V against the feed wire when not switching to earth, i thought it was just an open circuit. Ie 0V on the wire to the ECU.

Thanks in advance.

[mic*]

I think ive answered my own question if someone can confirm.

Unless i unclip all three injectors on the circuit to the ECU, there will be +12V at both terminals of the clip.

[o_man_ra23]

The voltage across the coil in an injector solenoid when there is no current is zero, as it is just a bent wire. As such, when there is power to one pin, and open at the other, both pins will be 12V.

Cheers, Owen

[mrk7]

Ok, you tech DIY gurus are freakin me out...haha.

Are you guys saying that the Jaycar DPA won't run another injector with 4age ecu unless another kit is added because it doesn't like peak n hold?

[Mos]

Are you guys saying that the Jaycar DPA won't run another injector with 4age ecu unless another kit is added because it doesn't like peak n hold?

AFAIK only the JDM AE86 4AGE ECU (stated earlier in the thread) has peak and hold and requires the adaptor.

Mos.