Gallons Per Hour Error?

[dcb]

I would like to try this at some point. Lemme know if anyone is in a position to try it (not sure if the zener helps anything or not, maybe just a reverse diode would be better so the signal current isn't divided between the diodes but reverse impulses get absorbed).

[dcb]

Made a little progress, built the circuit (with reverse diode instead of zener) and tried it out on the bench. The standard guino would be showing about 0.53 gph but this is showing 0.77, so there may be some futzing yet as the opto may add delays and possibly innacuracies, but should be better than nothing.

There is an additional lead that should be connected to the plus side of the injector to eliminate variables.



Note: If I change inj delayUS to 1600 then it goes back to 0.53 gph, don't know if that is the correct course of action yet, just sayin.

[dcb]

Ok, It turns out I have a relative with a 93 s10 with a 4.3 tbi collecting dust in the garage. Hopefully that is a peak and hold too (sounds promising) I think I will have to arrange some in-person fidgeting...

[consaka]

Everything I have ever read says that is a peak and hold injector. Should be very similar to what I have in the suburban. just smaller.

[Coyote X]

the 93 S10 is peak and hold. Same exact setup as I have in my Astro

[dcb]

Ok thx guys, now I just have to get the beast running

I got a haynes from the library (I love my library), and it "looks" like inj+ is connected to +12, so this might just be doable as a 4 prong deal using the "normal" connections, on a gm anyway.

[dcb]

I hotwired inj+ to the 12volt lead and grabbed my guino splitter and a spare guino and plugged it all into the metro. When I changed injdelayUS on the guino attached to this gizmo to 1350 they were pretty much within 1% of each other on the gph display and turned over the hundreths place on a gallon at the same time.

Now it may be that peakers open quicker given their higher current, and that the number should come back down a bit too. Any stats on that?

[dcb]

Ok, here is an updated circuit. If anyone is following and wants to try it, feel free (It might take me a while). I would say make injUS delay at least 1000, or if you are coyotex, just dial it in with that diagnostic port

This goes in line with the injector lead, and the connector already has 12v and ground, and you should already have a negative injector tap.

Here is the opto I'm using:
http://mouser.com/Search/ProductDeta...key859-LTV-815

The diode is a 1n4004
http://mouser.com/Search/ProductDeta...lkey821-1N4004

The resistors are 10k ohm and 470 ohm

[racprops]

Have you seen the Peak and Hold injector adaptor by JayCar?? They sell a kit that works with their duty cycle reader kit.

RIch

[dennyt]

It looks like I'm facing this peak & hold challenge in my '94 Subaru Loyale SPFI. I get GPH readings that go up with engine RPM, but not throttle position - coasting vs. floored gives the same reading, only shifting changes the GPH.

Any recent developments, or should I dive in with this op amp circuit?