I haven't seen any way of doing a high idle in the 2v gas motors. I have an idea, but I don't know how the IAC is actuated. Basically, I think there is a voltage wire to the IAC, this wire has a variable voltage to open and close the IAC to adjust the idle. So interrupt this wire with a relay, 30 to the IAC, 87a to the ECM. Then the coil to a switch. The rub is the 87, provide current at a voltage where it spins the engine to the desired RPM. I don't know how much resistance the IAC should have and what kind of potentiometer (wattage rating) to use to adjust the voltage or if it will require a power supply. Any ideas or input?

 

Sounds like you know how to build the swiss watch not just tell us what time it is. Wow I'm impressed and don't have a clue what you said other that what the IAC is supposed to be used for but hey.....It could very well work. Let us know.

 

I'd like to learn what voltages open the IAC how much, and if the ECM senses the load on the wire before I build something. But it's a basic idea to isolate a new power source from the ECM, and with enough current applied at the right voltage, it might adjust the idle up to 1000-1500rpms, maybe even 2k rpms. I can work through some of the circuit, but need a little help in the details.

To learn, I'd have to cut the power wire and read the amperage. It's not something I want to do right now, but maybe someone knows the impedance or amperage/voltage to run the IAC at various positions.

 

While your idea is sound, the pcm would not like this. You will have a service engine light on all the time and you may cause some drivability problems, as the pcm will likely try to adjust to what it interprets as a problem. Let me know if you would like to further discuss this.

 

Yep, I didn't think about the ECM not liking the new RPM set. Thanks.

 

Its not only the unexpected rpm, but the open circuit to the iac. The pcm monitors connections to sensors/outputs and would detect the open circuit.

 

How 'bout a brick on the bottom edge of the gas pedal instead?

 

The impedence the ECM saw on the IAC was one of my original concerns.

I use a 2x4 or my dewalt drill normally.

 

How about a high idle motor for a carbed motor. You know, the once that bumps the throttle lever a little to compesate for A/C????? Make up a bracket for it and hook it to a switch placed in the dash..... Should work ok I would think.

 

Actually, Idea #2 is like the first but using the cruise control servo. Same basic principle, apply a voltage to the cruise servo (motor only not the cruise control electronics) to draw the throttle body open. Wiring would be similar, but it would probably require disassembly of the cruise module. 30 to the servo and 87a to the module.

 

Could you fool the ECM into thinking the motor is still cold? This opens up the IAC and should not upset the ECM too much unless it goes into a richer burning mode. How many temp sensors report back to the ECM? If it is only 1 then it could work.

 

Cold ECT seems to only be 1000rpm or so. When I get around to doing something with this, I'd like 1500-2000rpms to spin my alt up to a high output range. Then using a pot to control the voltage would let me tune the RPMs a little which is why I was hoping to find a way to integrate one. But to answer your question, yes all you have to do is add resistance. The way I would do that is power the coil of a relay with a switch. 30 goes to the ECM on ECT wire, 87a goes to the ECT and 87 has a resistor inline to the ECT. This would let you throw a switch and change from the ECM reading actual engine coolant temp or your altered engine coolant temp.

 

Getting the idle up on my 6.8 has crossed my mind in the past also. It's been awhile since I was looking over the throttle trying to figure something out, but I remember putting some thought into hooking up a simple old school choke cable assembly. I was concerned with having a BIG pull switch in the cab for it, but I found cool small unit that I liked. I ended up moving onto other projects and lost track of where I saw the small cable switch unit. I have a link for the cable buried in a backup somewhere (I lost my laptop harddrive recently). I'll get to restoring my files soon and will let you know if it's something you might want to look into for your application.

 

When I had the IAC replaced the mechanic tested it with a something that was hooked up to the code reader outlet in the cab. He was able to change the idle with this device. I didn't notice if changed variably or it was just 1 single higher rpm setting, but it was slick when he did it.

 

This makes me wonder if some kind of programmer could handle the high idle?

Another option is something like this: High-Idlers we use them in limo's sometimes and they get the job done.