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RENIX High Idle Switch

GSequoia

GSequoia

Everyone says I'm a jerk.
NAXJA Member
Location
Torrance, CA
Has anybody come up with a way to install an electric high idle switch? I'm talking a switch on the dash to bump the idle up for high amerage devices like welders and winches.

Thanks,
Sequoia
 
I'm thinking of something similar - it's on my list of things to do. Haven't had much time to look into the idea lately - had to finish a couple other designs, been doing matrix algebra in maths for the last couple weeks, and I've got to work on those 760x bushings, now that Brett sent me a sample U-joint.

Still, it's on the list...

5-90
 
Working three majors and a "small business" keeps me busy for eight full days a week - and I'm finding I enjoy it. I'll probably enjoy it more when I'm done with school, and can really settle down into design work.

I haven't been able to update my site much (especially the "Works in Progress by Works in Progress page!) but I did put up some new prices, and I'm working on a "one-stop" tech archie as well. Nothing deep, but ID guides, and answers to "What **** do I have?" to save everyone some time.

Other things I'm going to have to add, once I figure out how to do them -
Metal vacuum lines. I agree with the individual who suggested it - and I never did like Nylon for stuff like that.
760x U-joint bushings. I'll be working on these next.
Copper radiator hoses. Using vibration stubs to attach, I'm working on what should be a real "lifetime" radiator hose - that won't cost as much as those silicone ones (ouch!)
Headlamp harness - I should have a working proto this month or next.

What else? I'd have to dig out my notebook...

5-90
 
I know from experience that if you run your xj with the MAP sensor vacuum line unplugged from the TB you get a very high idle.

I'd wonder about modifying an adjustable MAP sensor to perform simularly.
 
GSequoia said:
Has anybody come up with a way to install an electric high idle switch? I'm talking a switch on the dash to bump the idle up for high amerage devices like welders and winches.

Thanks,
Sequoia
Click to expand...
Any reason it needs to electric? There are plenty of mechanical one's
 
http://www.4x4getaways.com/ECUpinout.pdf

According to the Renix manual, pulling the AC Select line high will make the computer set the idle higher as if the AC is on and will also turn on the cooling fan.

It appears that it will need to be diode isolated, but that should not be too hard. I will do a little writeup and post the mod in a day or two.
 
Last edited:
I want electric well, because I want electric :) I'm going for that clean look that says "hey, I like wires." I've actually got the hand throttle that comes with it and intend to use it at least in the interim.

Tom - let me know what that puts the idle at.

Last just for the hell've it. What I'm thinking would be best would be an engage switch and perhaps a knob to crank it up some (to get more or less amperage out of the welder); a project that I may work on. I might modify the cruise control (if I can ever get the damn thing to work!) to read speed off the crank sensor (a toggle switch to go between crank sensor and speed sensor)...

Excuse me..I'm rambling.

And Sean...

BITE ME! Besides, you'll probably need to use it next year in Moab anyway!
 
This fix will only move it up a couple of hundred rpms.

Hey, get a Solevac from an 85 2.5L with a Carter YFA carb. It is a electric actuated vacuum solenoid and is adjustable. Just rig a bracket.
 
I know this is an old thread but I just wanted to throw some info in here of what I did for future searchers.

My A/C refrigerant(R12) was too low to operate system,
and I wanted a way to turn on my fan and kick up the idle.

I disconnected A/C clutch power (could run a switch or to a relay)
jumpered low refrigerant sensor.
Now I select A/C or defrost aux fan engages and idle kicks up around 200rpm
Only down side is in the summer I'm blowing warm air in cab
May turn compressor into OBA

Old Man What would the diodes be for?
 
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if you want electric, I guess you could splice into the cruise control solenoid control lines, do some diode isolation, and then set whatever speed you want... Otherwise, maybe some trickery with the MAP or TPS sensor wiring? I believe I saw a mod that involved adding a resistor inline with one of those, but I forget what exactly it accomplished.
 
Well since this thread has been given a new life, you all were looking at stuff that is way more complicated than you need. All it takes is a variable (or fixed) resistor in parallel with the TPS sensor, and a single pole double throw switch to switch from the TPS to the fake TPS. Rig up and try different fixed resistors, or just use a variable resistor.
 
Damn, Mike, that's a pretty good idea.
Which wire-the input or the output...actually, I can visualize this-5 volts into the variable, and the output back to the ECU.
Hmmmmm, I might have to try that.

Nick

Ecomike said:
Well since this thread has been given a new life, you all were looking at stuff that is way more complicated than you need. All it takes is a variable (or fixed) resistor in parallel with the TPS sensor, and a single pole double throw switch to switch from the TPS to the fake TPS. Rig up and try different fixed resistors, or just use a variable resistor.
Click to expand...
 
I suspect that would just flood the engine to run really rich. The computer adjusts fuel according to air so if you tweak the TPS signal you are telling it that air flow has increased when it hasn't. What you want to do is increase the actual airflow, so that the computer can react accordingly. The best way to do that would be to goose the signal going to the IAC.
 
Nickfast said:
Damn, Mike, that's a pretty good idea.
Which wire-the input or the output...actually, I can visualize this-5 volts into the variable, and the output back to the ECU.
Hmmmmm, I might have to try that.

Nick
Click to expand...

The resistor needs to be wired up just like the TPS, input 5 volt wire to the resisitor (use a Y splitter for the 5 volt from the ECU), output from the resistor goes to the toggle switch. Output from the TPS also goes to the toggle switch. Then just toggle between the outputs to the ECU using a single pole double throw switch. That simple.
 
ehall said:
I suspect that would just flood the engine to run really rich. The computer adjusts fuel according to air so if you tweak the TPS signal you are telling it that air flow has increased when it hasn't. What you want to do is increase the actual airflow, so that the computer can react accordingly. The best way to do that would be to goose the signal going to the IAC.
Click to expand...

It will work as the ECU will adjust the IAC and the fuel injection for a higher engine speed. The limit, or upper end will depend on the IAC control limits. The O2 sensor input & ECU control will not let it flood. It will just max out the IAC and stop there. Should be able to reach 3000 rpm, at no load easy, with IAC at max opening, based on all the tests I ran on Renix TPS problems a few years ago.

I would test a TPS at the idle position, ohms, engine off for resistance, or look up the values in my old "RenX files" thread. IIRC it is about 2200 ohms at idle. So get a 2000, 500, and several 100 ohm resistors, try various combos of them in series, to get the rpm you need. 2300 to 2500 ohms should do it.
 
ehall said:
I think the computer will see the rich mixture, look at things like MAP input, and then turn down the fuel mixture thereby canceling out the added fuel that was not accompanied by increased air.

Worth a test though
Click to expand...

I know from personal experience that the Renix IAC can open up the air flow to reach at least 3000 rpm with bad TPS data, and the throttle at the idle position. When the IAC is wide open, it adds fuel to balance the A/F ratio.
 
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