AFM delete CEL - Miata Turbo Forum - Boost cars, acquire cats.

Welcome to Miataturbo.net   Members
 


MEGAsquirt A place to collectively sort out this megasquirt gizmo

Reply
 
 
 
LinkBack Thread Tools
Old 10-01-2007, 11:06 AM   #1
Senior Member
Thread Starter
iTrader: (2)
 
Join Date: Mar 2006
Location: MA
Posts: 885
Total Cats: 2
Default AFM delete CEL

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?
devin mac is offline   Reply With Quote
Old 10-01-2007, 11:44 AM   #2
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,900
Total Cats: 1,793
Default

did you cut the AIT signal to the ecu?

betcha ya did.
Braineack is offline   Reply With Quote
Old 10-01-2007, 12:01 PM   #3
Senior Member
Thread Starter
iTrader: (2)
 
Join Date: Mar 2006
Location: MA
Posts: 885
Total Cats: 2
Default

if by "cut the AIT signal to the ecu" you mean "disconnect AFM and throw it in a garbage bag" then yes.
devin mac is offline   Reply With Quote
Old 10-01-2007, 12:08 PM   #4
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,900
Total Cats: 1,793
Default

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.
Braineack is offline   Reply With Quote
Old 10-01-2007, 12:10 PM   #5
Senior Member
Thread Starter
iTrader: (2)
 
Join Date: Mar 2006
Location: MA
Posts: 885
Total Cats: 2
Default

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 is offline   Reply With Quote
Old 10-01-2007, 12:12 PM   #6
Senior Member
Thread Starter
iTrader: (2)
 
Join Date: Mar 2006
Location: MA
Posts: 885
Total Cats: 2
Default

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.
devin mac is offline   Reply With Quote
Old 10-02-2007, 10:34 PM   #7
Supporting Vendor
iTrader: (5)
 
Join Date: Jun 2006
Location: Duluth, GA 30097
Posts: 798
Total Cats: 0
Default

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.
FoundSoul is offline   Reply With Quote
Old 10-03-2007, 09:49 AM   #8
Senior Member
Thread Starter
iTrader: (2)
 
Join Date: Mar 2006
Location: MA
Posts: 885
Total Cats: 2
Default

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?
devin mac is offline   Reply With Quote
Old 10-03-2007, 11:00 AM   #9
Supporting Vendor
iTrader: (5)
 
Join Date: Jun 2006
Location: Duluth, GA 30097
Posts: 798
Total Cats: 0
Default

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).
FoundSoul is offline   Reply With Quote
Old 10-04-2007, 12:54 AM   #10
Junior Member
 
Join Date: Jun 2006
Location: LV, NV
Posts: 225
Total Cats: 0
Default

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.
mschlang is offline   Reply With Quote
Old 10-04-2007, 10:33 AM   #11
Senior Member
Thread Starter
iTrader: (2)
 
Join Date: Mar 2006
Location: MA
Posts: 885
Total Cats: 2
Default

sounds good. i'll probably do it tomorrow when i get the car back from the exhaust shop.
devin mac is offline   Reply With Quote
Old 10-04-2007, 10:34 AM   #12
Senior Member
Thread Starter
iTrader: (2)
 
Join Date: Mar 2006
Location: MA
Posts: 885
Total Cats: 2
Default

Quote:
Originally Posted by FoundSoul View Post
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).
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)
devin mac is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
Project Gemini - Turbo Civic on the Cheap Full_Tilt_Boogie Build Threads 59 12-15-2017 09:00 PM
Raleigh: Fiberglass headlight scope, 1.6L ECU, AFM, Hardtop latches, more bigmackloud Miata parts for sale/trade 13 09-22-2017 01:34 PM
Going back to stock. Need some 1.6 parts. Trent WTB 2 10-01-2015 01:15 PM
Got bad Crank Angle Sensor and Random Misfire codes, but runs fine. Greasyman General Miata Chat 2 09-28-2015 11:44 AM


Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 07:04 AM.