Len Posted March 27, 2002 Share Posted March 27, 2002 Tony On a thread back in 1/28/02 in High Tech Board "Fooling the Stock ECU" touched a bit on that subject. Your right; that would be the berries to rig up a reostat of sorts to control signal from AFM to stock ECU to lean or richen injectors. I think that would be along the lines of what Bill "awd92gsx" is trying to do; hooking up his Apexi Super AFC. If he figures which wires to hookup on AFM then we can go from there rigging up possibly a reostat. Quote Link to comment Share on other sites More sharing options...
VinhZXT Posted March 28, 2002 Share Posted March 28, 2002 Good idea.. I will go home and find out which wire will send the signal back to the ECU. Instead of connecting the potentiometer I will connect a switch to completely disconnect that wire. This should be good under boost.. .. Quote Link to comment Share on other sites More sharing options...
DAW Posted March 28, 2002 Share Posted March 28, 2002 I used a potentiometer wired into the water temp sensor circuit to adjust mixture, and for selecting a fixed value resistor for this circuit where I wanted the baseline mixture to be. A resistor can also be placed in the cylinder head temp circuit for mixture control. You'll probably want to adjust/alter baseline AFM doorspring tension before proceeding with the sensor potentiometer or resistor. DAW Quote Link to comment Share on other sites More sharing options...
Len Posted March 28, 2002 Share Posted March 28, 2002 I remember the mechanic who owned my 83 280ZXT used a resistor on the cylinder temp sensor to richen it up. Good idea on AFM spring tension to compensate for richer mix. Possibly even considering lowering O2 sensor to show .75 instead of the normal .90 to .95 volts would also contribute! Quote Link to comment Share on other sites More sharing options...
Tony240ZT Posted March 28, 2002 Author Share Posted March 28, 2002 I was thinking about how the SDS has that adjustable nob for lean/richness. I'm assuming it's a potentia meter adding resistance to the wire that tells the computer how much fuel to supply the engine. Couldn't the same idea be used with the stock 280ZX Turbo AFM. I know when you unplug the AFM the car runs as rich as possible, and this would be a situation where there is unlimited resistance between two wires, but which ones? If I were to tap into the wire that is sending the signal back to the ecu, put an adjustable potentiameter in there couldn't I richen the mixture? I could even set the AFM to initially run lean, then dial my POT to make the car run stoich, that way I have adjustment on both sides of the spectrum. Now, I may be getting old and lazy because I don't want to get out of my car and adjust it in the engine compartment, but really, I think that having this sort of adjustment in the cabin could be usefull. Let me know what you guys think, and if you know which wire is the sending wire for the AFM possition. Quote Link to comment Share on other sites More sharing options...
Tony240ZT Posted April 2, 2002 Author Share Posted April 2, 2002 Okay guys, nuff talkin about it, time to prove I'm not all talk. Turns out the Yellow/Red wire is the one that sends the signal to the ECU. I don't have my notes in front of me right now, but the voltage starts out at around 8.2V and then falls off nearing 0 V.. I haven't had a mounting case for my air/fuel gauge, so I thought that would be a good thing to take care of. I've never messed around with fiberglass before and thought it would be fun to make a little gauge pod that I could then install the tuning hardware. Currently have a single potentia meter with an on/off switch that I bought from radio shack. Used the on/off switch part to power a small light. Plan on having two nobs (that's why I have two lights), one for leaning things out and one for richening. I couldn't think of an easy way to put them into one nob. I'm still working on the amount of resistance needed. I picked up a 5K ohm one and it hardly changes a thing. It drops the voltage only about .2 volts, so I'll be trying out a larger one when radio shack opens back up. Thinking of running my cable down into the defrost air duct back there, if anyone else has a better idea let me know. In the picture the car is cold and that's why it's running to the lean side, after warmed up it runs rich, which has been costing me a lot for gas. I figure installing the lean nob and setting it up correctly should save me a lot in gas money. After dropping in the Mercedes 450SL injectors I can't adjust my AFM to run lean enough, and I get only around 9-10mpg!!! Not to mention I smell of raw gas after getting out of the car after a drive. I'd be interested in other people who have made custom gauge pods. Quote Link to comment Share on other sites More sharing options...
DAW Posted April 2, 2002 Share Posted April 2, 2002 I used a potentiometer to calibrate/select for best all around resistance value, then installed that resistor and removed the potentiometer. However, if you're leaving it in place maybe a stepped type switch would be best (with detents) so that you can give it a certain number of clicks if you need richening while driving so that you can keep your eyes on the road and still adjust acurately. DAW Quote Link to comment Share on other sites More sharing options...
Tony240ZT Posted April 3, 2002 Author Share Posted April 3, 2002 Good idea, I'll look around for that type, or maybe I can get something to convert the one I have into that type. Quote Link to comment Share on other sites More sharing options...
clint78z Posted April 3, 2002 Share Posted April 3, 2002 If I was fudging the computer here's what I would do set the spring tension in AFM to give to proper mixture at wide open throttle. Next I would hook in the potentiometer to lean the mixture, but I would hook it through the TPS switch to allow it to bypass lean setting under full throttle. It's a pretty simple switched circuit that should work much better than what you have. Quote Link to comment Share on other sites More sharing options...
Tony240ZT Posted April 4, 2002 Author Share Posted April 4, 2002 I don't know why I didn't think of that myself. That might solve the problem I've been having where it seems to run crappy except under full boost. The only time it really needs to be lean is when I'm under a lot of load. I wish I had an electrical vacuum switch of some sort. Is there a such thing out there? A switch that would switch at a set amount of vacuum or presure? Quote Link to comment Share on other sites More sharing options...
Scottie-GNZ Posted April 4, 2002 Share Posted April 4, 2002 Hobbs switch. Quote Link to comment Share on other sites More sharing options...
Cody 82 ZXT Posted April 8, 2002 Share Posted April 8, 2002 Tony check this link for the switch . Quote Link to comment Share on other sites More sharing options...
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