VX lean burn monitor - enhanced how to desired

[jadziasman]

I have read Krousdb's original post on TomO's VX links and info and need some assistance in understanding what it takes to tap into the ECU. I am somewhat fearful of cutting any of the wires at the ECU because some of them are shielded (to guard against stray EMF's I guess).

So, to those of you who have already wired up their lean burn monitor to D14 and D16, is there any way of doing this without cutting the existing wiring? As much as I would love to have this monitor to improve my mpg, I won't risk messing up my currently perfect PGM-FI without more knowledge.

[rgsRSX06]

careful with the lean burn, you could get detonation/pining and destroy your engine in short order. You should if you have a Honda check out Hondata for an ecu upgrade that lets you tinker with air-fuel and timing.

[Danronian]

I disagree. Hondata is killing grass-roots tuning and PGM-FI.org. Don't use them.

I would also love a how-to on this so I could see when my car goes into lean-burn.

[dogncatboy]

Originally Posted by Danronian

I would also love a how-to on this so I could see when my car goes into lean-burn.

Ditto.

[rlprlp1]

I carfully shaved the insulation off the two wires just enough to solder into them. Taped them up when i was done.

[93dagsr]

Originally Posted by rlprlp1

I carfully shaved the insulation off the two wires just enough to solder into them. Taped them up when i was done.

which ones??...pics??..

[GasSavers_vxhatch]

Everything you need to wire a voltmeter, including wire color codes is in the main post, http://www.gassavers.org/showthread.php?t=2427

What I would like to implement instead of a voltmeter is a dash light that glows when in lean-burn mode. I noted when a new member from Portugal described his Civic has a Honda provided "ECONO" indicator that lights when in lean burn. Here's the post: http://www.gassavers.org/showthread.php?t=5535
Read the 5th paragraph and check out the 2nd pic.

A simple comparator circuit could be built to switch a dash mounted LED on whenever the monitored voltage is in the lean-burn range. I'll try and post back with a sample circuit next week.

Doug

[4bfox]

Heck yeah! Put me down for a kit, too...I can figure this stuff out usually, but it makes my head hurt. And I don't mind paying for convenience

[GasSavers_TomO]

^^^ when you hook up the DMM to D14 and D16 you are watching the LAF signal compared to the Reference signal, not chassis ground. You can also hook up your DMM a different way and read the entire spread of the LAF signal. In which case the voltage will always be positive and anything above the reference voltage (2.7V measured from D16 to ground IIRC) will be lean burn. That is the way that I'm intending on setting up the comparator circuit.

I'm also looking forward to your input on ways to modify/use the circuit in the LAF sensory circuit.

[GasSavers_vxhatch]

Originally Posted by TomO

^^^ when you hook up the DMM to D14 and D16 you are watching the LAF signal compared to the Reference signal, not chassis ground. You can also hook up your DMM a different way and read the entire spread of the LAF signal. In which case the voltage will always be positive and anything above the reference voltage (2.7V measured from D16 to ground IIRC) will be lean burn. That is the way that I'm intending on setting up the comparator circuit.

I'm also looking forward to your input on ways to modify/use the circuit in the LAF sensory circuit.

Thx Tom, I also figured this out on my own by carefully reading-digesting & re-reading the original thread. I drew a schematic, based on the autospeed design and had a design engineer look it over. He said it should work fine, but there is a better way to do it. The 470 ohm resistor will be between +12v and ground in the non lean-burn state and as a result it will consume energy while performing no useful work. When in lean-burn, the output of the comparator is switched off (open-circuit) and the 470 ohm resistor serves as a voltage divider to get the LED input voltage into the proper voltage range (and brightness). Along with some schematic changes, if the comparator and LED are selected such that the comparator output current rating is capable of driving the LED on its own, the circuit may be designed to consume no energy in the LEF off state.

doug

If you like, PM me with a FAX number and I'll send you the schematics I've scratched off

PS: In the VX, the indicator will have only two states LED on and LED off, there will be no flashing mode, which I'd find annoying anyway.