devin mac

iTrader: (2)

obviously getting a check engine light now that i've gone ahead and deleted the AFM on my car. i'm NOT running an MSPNP, so i don't really need to send any particular signal to the stock ECU. I just need to figure out a way to get the CEL to turn off. Think a resistor jumpered into the AFM connector would do the trick? I could ohm out the IAT and see what it reads, and take a trip to radio shack and get an appropriate one to somewhat match.

thoughts?

Braineack

iTrader: (62)

did you cut the AIT signal to the ecu?

betcha ya did.

devin mac

iTrader: (2)

if by "cut the AIT signal to the ecu" you mean "disconnect AFM and throw it in a garbage bag" then yes.

Braineack

iTrader: (62)

the ecu needs some signal or else it will throw a code, so the new signal from the GM ait should be sliced into the stock wiring somewhere.

if it's not it will throw a code.

devin mac

iTrader: (2)

yeah, i might just do that. my thought, though, is that since an AIT is essentially just a variable resistor, if i somewhat match the resistance of the sensor as it sits, that'll fool the ecu into thinking SOMETHING is there and stop it from complaining. then i can just jumper it and seal it up, rather than running and splicing more wires from the AIT.

i'll try the resistor theory and see if it works, if not, i'll run the AIT to it.

devin mac

iTrader: (2)

oh, just to clarify, my AIT goes directly to the MS harness and not into any of the stock wiring. dunno if that was unclear or not.

FoundSoul

iTrader: (5)

If you remove the IAT an replace it with a resistor, true it 'might' stop the CEL, but your fueling with be WAY off and could cause you to run very rich or very lean or both depending on the current true IAT that you are no longer measuring.

devin mac

iTrader: (2)

hmm, apparently i wasn't clear. the IAT wiring goes DIRECTLY to megasquirt. i'm NOT using a PNP. i'm not removing anything, just adding a resistor in the AFM plug rather than running a pair of wires from my IAT all the way to the other side of the engine bay to the AFM plug. I'll still be feeding megasquirt an IAT signal. i'm not quite THAT dense. (though, i have done dumber things in the past, i imagine... :-) )

that said, i'm only trying to make the stock ecu think there's still an AFM connected so the damn CEL doesn't stay lit.

make more sense?

FoundSoul

iTrader: (5)

Ah... you're running a parallel install with the stock ECU in place, just trying to fool it. Yes that should work as long as it's in the range of expected values, and almost anything would be. A 330ohm resistor will make it think it's relatively warmed up all the time (176 degreesF). You could go a bit lower in value but I bet that will suffice. Check it to make sure it doesn't get warm, if it does increase the wattage rating of the resistor, same resistance though. Or just start with a 1watt resistor to begin with (still check it but I bet it will be fine).

mschlang

Or, clip the yellow/black wire coming off the stock ecu, E on connector 1. I was going to try out a resistor, but I found out the stock ecu controls idle and AC fine without it.

devin mac

iTrader: (2)

sounds good. i'll probably do it tomorrow when i get the car back from the exhaust shop.

devin mac

iTrader: (2)

and yeah, it's a KingOfL33t setup with the MS signals mostly tapped inside the stock ECU itself. i think all the stocker is controlling now is idle and AC (if it still existed)