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variable resistor bad?

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Old 01-23-05 | 06:50 PM
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variable resistor bad?

my idle is hiding somewhere and i cant get it to work so ive been testing everything with an ohm meter. i tested the variable resistor (for idle mixture) giong by what the fsm says but i dont know what im doing so i dont know if its bad or not. i have the ohm meter set to x1Kohm to test it like the fsm says. if i test pins A-C and adjust it untill it reads around 4Kohms and the test pins B-C and it reads 1. if i adjust it richer, pins A-C have more resistance, pins B-C have less resistance. now i already know that my variable resistor is broken because it will turn indefinatly either way and its only supposed to turn like 3/4 of a turn either way. i was wondering what the different resistance means to the ECU as far as what is rich and what is lean so i can get it to run right untill i find a good variable resistor. and if anyone has an extra that they know is still good, how much do you want???
Old 01-23-05 | 07:44 PM
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so nobody knows then?
Old 01-23-05 | 07:48 PM
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I broke mine too, so I unplugged it and took it out. The consensus was that if you unplugged it and just left it out the ECU would fall back on some default.
Old 01-23-05 | 07:54 PM
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so there is like a default setting or it just stays where it was before you unplugged it. and does your car idle ok without it?
Old 01-23-05 | 08:00 PM
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Question Variable resistor removed?

Originally Posted by dDuB
I broke mine too, so I unplugged it and took it out. The consensus was that if you unplugged it and just left it out the ECU would fall back on some default.
dDuB or anyone else, Do you know the particulars of ECU default when the variable resistor is removed?
Old 01-23-05 | 08:01 PM
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Rock solid idle with no emissions at all, no variable resistor, no BAC, TB mod, aux ports open all the time with large porting, etc etc etc...

Idle is tricky sometimes, you just gotta troubleshoot it until you can get things right.

What things have you played with when trying to fix your idle?

As far as I know the ECU has a default setting mapped into it for if the variable resistor failed or wasn't there, that's what I was told anyways. So unplugging it would resort to that setting. Even when my variable resistor was working it didn't change idle hardly at all.
Old 01-23-05 | 08:02 PM
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Originally Posted by Chuckles
dDuB or anyone else, Do you know the particulars of ECU default when the variable resistor is removed?
What kind of particulars? Seems like people are a little too afraid of this idea for some reason

Here's an easy test, unplug it and see if your car idles better or worse. If it idles better leave it out, if it gets worse well then plug it back in, very simple.

But like I said before I broke mine it wasn't doing a whole lot anyways.
Old 01-23-05 | 08:06 PM
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well i have everything else down and now how to set it, the one adjustment i dont know about is the one screw closest to the front of the car on the TB, near the top. when i turn it, the idle starts bouncing so i just adjusted it to the exact point where the idle stops bouncing. the tps is adjusted right. its just that nomatter what i do, i can not get it to catch itself and idle after letting off the gas. it will idle just fine if i tap the gas before it stalls, but will not catch itself without help.
Old 01-23-05 | 08:10 PM
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Is this all the time? Only when cold? Only when hot?

Are you talking about the one on top of the dynamic chamber with the rubber cap over it? That one didn't do a whole lot for me.

Is your problem a LOW idle or just an idle that wont hold itself? What rpm does your car idle at when at operating temp without you blipping the throttle to help it?
Old 01-23-05 | 08:49 PM
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well i took out the warm up system and everything so i dont care about how it runs when its cold as long as it runs when its warm. this is all at fully warmed up temperature. im not talking about the idle adjust screw with the rubber cap. its on the TB just in front of that screw(the one with rubber boot) and has a little nut on it to keep it from turning. my problem is not a low idle, when it idles it is rock solid, no bouncing at all and it will idle at about 850 rpm. the problem is that it wont catch the idle by itself like when im going down the road and take it out of gear, normaly it will just drop down and idle but mine just drops down all the way and dies.
my next idea is that it is the BAC that isnt working, i just went out and drove my car without the variable resistor and it seemed to run smoother, less jumpy at low rpm so i think i will leave it out. but it did not change the idle at all so i tried to adjust it and it still will not idle.
Old 01-23-05 | 09:40 PM
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From: chicago land
ok i completely give up on letting my car control its idle, is it possible to remove the BAC and just adjust the idle with the throttle plates? i know this is bad to do because your idle will drop with a/c or power steering but i dont car, i dont use a/c and i dont turn unless im moving. can someone point me to a writeup on this or something, i will keep searching but there are hundreds of idle threads and i cant find what i want.
Old 01-23-05 | 10:54 PM
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well i got the damn thing to idle, i took out the variable resistor, unplugged the bac, connected the intitial set connector and got it to idle at about 900 rpm. then i reconnected everything (except the variable resistor because its broke) and now it idles ok... still a little wierd but it will get me to work and i can tune it tomorrow
Old 01-23-05 | 11:03 PM
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well i got the damn thing to idle, i took out the variable resistor, unplugged the bac, connected the intitial set connector and got it to idle at about 900 rpm. then i reconnected everything (except the variable resistor because its broke) and now it idles ok... still a little wierd but it will get me to work and i can tune it tomorrow
Old 01-23-05 | 11:09 PM
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Congrats. Things get all the more simple as you start removing crap doesn't it
Old 01-23-05 | 11:13 PM
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what a variable resistor does is that when you turn it, one side increases resistance while the other decreases. what it sounds like is that you have a broken armature.. no worries.. you dont really need the damn thing anyways.
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