How to "hotwire" fast idle?

[ghunt]

Is it possible to wire the fast idle solenoid to a switch, so that if the switch is off, it will work normally (i.e. come on automatically if the engine is below a certain temp), but will turn on if I flip the switch on and then back off if I flip the switch off?

I just hate it when the weather is cold and I start up the truck, and it's been running in the past couple hours so it's warm enough the fast idle won't kick on, but it still runs crappy for the first little while after I start it (and I don't want to overuse the GP's). I'd like to connect it to a switch so I can turn it on when the engine is kinda warm like that.

 

[Brianedwardss]

I have this type of setup for my cold advance. I just spliced into the wire by the solenoid and ran the extra wire to a switch. I ran a power wire to the switch with a 25 amp fuse and I get the best of both worlds. Were not dealing with an ECM here, I think just makin sure your link is fused is about all that's important.

 

[F350farmboy]

Is this what you're talking about?
High Idle Manual override

 

[SparkandFire]

I was noticing on the diagram that you need a diode in the circuit to keep the cold advance from coming on manually when you energize the high idle solenoid. Is it necessary to separate the two like that, or could you energize the advance and high idle at the same time???

 

[6.9poweredscout]

what does the advance do anyhow?

btw i have both disconnected and even when its cold it only chugs for a few seconds...

-Jon

 

[sle2115]

what does the advance do anyhow?

It advances the timing and I don't think you'd want it on long term and on a hot engine. If yours is working correctly, when you start cold, you'll notice a little more clatter from the advanced timing.

 

[6.9poweredscout]

It advances the timing and I don't think you'd want it on long term and on a hot engine. If yours is working correctly, when you start cold, you'll notice a little more clatter from the advanced timing.

no worries, i unplugged it completely! it seemed like the fast idle sole and the advance would randomly kick on and off.

sry for the hijack. ;p

-Jon

 

[LCAM-01XA]

I was noticing on the diagram that you need a diode in the circuit to keep the cold advance from coming on manually when you energize the high idle solenoid. Is it necessary to separate the two like that, or could you energize the advance and high idle at the same time???

I had no diode in my setup at first, I noticed that once the engine warmed up good if she was just idling in my driveway and hit the switch and then push the pedal down a bit to set the high-idle solenoid the engine would enter a semi-runaway mode, revving up all on its own to nearly 2500 rpms, then dropping down to under 500 rpms where the governor barely managed to catch it before she stalls, and then off we go in the high rpms again... Installed the diode, no more timing issues.

 

[sootman73]

i have my cold advance on a switch so that i can shut it off before i start driving. i usually dont have time to wait for my truck to warm up that bit to turn off the high idle and advance and i am starting to eat glow plugs because of the advanced timing. this way i can shut it off before i drive. it was never a problem before i had my timing set at the rally and was eight degrees retarded.

plus its kinda fun to hit the timing switch and feel her pull hard. i can go up a # of boost at almost any rpm by that......

 

[sle2115]

sry for the hijack. ;p
-Jon

Not a hijack, the OP asked what would happen if it wasn't dioded too, so I was just trying to answer both questions, yours was the closest to quote!

 

[Agnem]

The cold idle advance causes an increase in internal pump presure and advance by controlling the rate at which fuel exits the pump through the top cover to the return line. It's just a solenoid like the Fuel Shutoff Valve which is energized the whole time your running, so it won't hurt the pump to manually control it, but as was indicated the additional 2 to 3 degrees of advance on a warm motor would not be wise for long term use. Most people put a switch in so they can have high idle only, which gives the benefit of keeping the motor warm, and the battery charging on those cold nights when all the lights are on and nobody is home.

 

[LCAM-01XA]

Most people put a switch in so they can have high idle only, which gives the benefit of keeping the motor warm, and the battery charging on those cold nights when all the lights are on and nobody is home.

Haha, Mel, when all my lights are on and nobody is home the only thing that will keep my batteries charged is a big heavy brick on the throttle pedal

 

[gdhillon]

I read Rons DIY, im unclear on how I would hook up to a toggle switch and locate a fused power source?
Also, instead of soldering could I use merrets/wire nuts?

 

[gdhillon]

BTW im a fan of Ron's red lines maybe I'll have to paint mine