Hey guys last week i was adjusting my timign idle ect and decided it try to lean out my idle to save some gas. However upon turning the variable resistor iv come to see it doesnt do a god damn thing. ive turned it to its extreme in each direction without a change in engine sound or behavior. Is it possible its broke? From what i read the car should almost shut off when turned too lean.

 

were is the variable resistor located?

 

Its easy to tell if its functioning.. pull the harness plug... Set a digital milti-meter to Ohms and plug it into the VR's plug.. the resistance should change as you move the pot from one extreme to the other...

As to WHAT the resistance spec IS.... I dunno..

the OTHER way is to set the multimeter to VOLTAGE, and back probe the connection while the ignition is on and turn the pot an see if the voltage changes.. again.. i dunno the spec.. BUT, most sensor circuit voltages run fro 0-5 volts or 0-1volt... (the variable resister set the reference voltage for the computer... the computer uses this reference voltage for everything.. thats why they say not to mess with it.

 

is over on the passenger side strut tower by the pressure sensor.. that little black cylinder that eveybody wonders what the hell it is..

 

lol...i always wonder what the hell that thing did!!!! do i really need that thing anyhow seeing my idle is controlled by my idle stopper screw?

 

Your idle speed is controlled by the screw you are talking about, the Variable resistor controls the idle fuel mix

 

hmmm....more crap to play with...

 

Was your ISC grounded? Since yours is an 86 Base, let me help you out here. Starting on page 4A-77 of the FSM, tells you how to adjust the variable resistor should you choose to start messing with it.

 

My friend tried adjusting the one on my car and broke it. Seemed to help almost.

 

Is your idle speed in spec?
If it's too high, the stock ECU ignores that idle mixture screw.

BTW, adjusting that screw lean will do almost nothing for your gas mileage...unless you like to idle your car for 30 minutes in the garage for some odd reason.


-Ted

 

. . . or if you're idling a lot in traffic :p

But I gotta warn ya; RX-7s like to idle rich!

 

I dunno whats wrong with my idle. I set it to 750, set my timing and it still misses constantly and has the tach waving up and down a hundred RPM's in each dorection. I was hoping the VR would help me,

 

do s5 have a variable resistor

 

sounds more like your TPS is out of whack not the mixture.

the variable resistor when extremely rich or lean will cause a sort of misfire running condition at idle, the TPS and idle screw can cause the idle to fluctuate hundreds of RPMs.

also be sure you do not have any leaks in the intake system, ie. a ripped or torn intake hose, missing vacuum caps or lines disconnected.

 

All hoses are good, im gonna look up the procedure for checking/setting the tps.