gsl-se variable resistor?
84SE-EGI helpy-helperton
Joined: Oct 2002
Posts: 3,584
Likes: 542
From: Phoenix, AZ
Steve's right - this is the Idle Mixture FINE adjustment, and adjusts idle air/fuel mix through a Rich and Lean (R and L) setting. This should be the LAST thing that you use to adjust idle speed, however, since air controls idle speed, mixture controls idle 'quality'.
The Mazda factory put some paste in there to prevent people from adjusting this, since the idle test is a mandatory test for importing cars and emission testing. A simple 1/4 turn of this setting can drastically increase unburned hydrocarbons which could result in your car failing emissions testing next time you go in. The total mvoement on this variable resistor is about 270 degrees.
The FSM adjustment requires that the car be hooked up to a exhaust 'sniffer' and then idle is adjusted to 800 rpm (minus vacuum systems) with air controls, variable resistor is turned to the minimum HCO output, and then resealed; idle returned to factory defaults, and then reattach vacuum system.
Kind of a hassle if you don't have the emissions 'sniffer' equipment, but you can guess this pretty closely by going just to the rich side of the smoothest idle 'quality'. Quality here is defined as a smooth and consistent idle that doesn't stumble (too lean), and doesn't hunt (too rich). HTH,
The Mazda factory put some paste in there to prevent people from adjusting this, since the idle test is a mandatory test for importing cars and emission testing. A simple 1/4 turn of this setting can drastically increase unburned hydrocarbons which could result in your car failing emissions testing next time you go in. The total mvoement on this variable resistor is about 270 degrees.
The FSM adjustment requires that the car be hooked up to a exhaust 'sniffer' and then idle is adjusted to 800 rpm (minus vacuum systems) with air controls, variable resistor is turned to the minimum HCO output, and then resealed; idle returned to factory defaults, and then reattach vacuum system.
Kind of a hassle if you don't have the emissions 'sniffer' equipment, but you can guess this pretty closely by going just to the rich side of the smoothest idle 'quality'. Quality here is defined as a smooth and consistent idle that doesn't stumble (too lean), and doesn't hunt (too rich). HTH,
84SE-EGI helpy-helperton
Joined: Oct 2002
Posts: 3,584
Likes: 542
From: Phoenix, AZ
Idle 'quality', only. Adjust it until it's smooth and leave it there. You're only changing the rheostat signal being sent to the ECU which tells the fuel injection system how often and how long to fire.
Plus, this ONLY affects idle; as soon as you're underway (over 1k rpm), you're running off of closed-loop AFM signal regarding incoming air volume, and O2 sensor regarding outgoing HCO's - if problems with either of these, then it goes to open-loop standard fuel mapping, which gives less performance (but only slightly).
If everything else is running well, you should be fine. The fine idle mixture adjustment is the LAST thing you want to mess with, since it can disguise other problems like vacuum leaks, and BACV problems. HTH,
Plus, this ONLY affects idle; as soon as you're underway (over 1k rpm), you're running off of closed-loop AFM signal regarding incoming air volume, and O2 sensor regarding outgoing HCO's - if problems with either of these, then it goes to open-loop standard fuel mapping, which gives less performance (but only slightly).
If everything else is running well, you should be fine. The fine idle mixture adjustment is the LAST thing you want to mess with, since it can disguise other problems like vacuum leaks, and BACV problems. HTH,
