Why the diode?

[BrianX128]

http://www.oilburners.net/articles/high idle override.htm

So I'm planning on doing this this coming week when I'm off work. Being able to force my high idle will be nice as even though I live in the middle of nowhere, the first main road I turn on has a blind spot and sometimes you just gotta go so I like to be warmed up when I leave.

What I don't get is why am I putting a diode anywhere? If the temp switch normally turns both of these items on why do I not want to do that when I throw the switch in the cab? If I am only letting it idle for two or three minutes this way in the mornings what is the reason that I can't just splice a wire from a switched toggle switch in the cab directly to the cold advance solenoid?

Thanks for any help. I don't even know where I will find a diode if it's necessary to do it this way as my radio shacks are long gone.

 

[DaveBen]

The diode stops the advance circuit from advancing the timing on a cold start. You can leave it out if you want to.

Dave

 

[BrianX128]

Will it really make a difference for my purposes of warming up the engine a little more over warmer weather times in the early mornings? I mean it's super easy to do and if it isn't as good for it when it's 45-50 outside over summer for me to throw it on that way I can easily put it in, I'm just confused as to what advancing the timing as well will really "do".

 

[MTKirk]

Will it really make a difference for my purposes of warming up the engine a little more over warmer weather times in the early mornings? I mean it's super easy to do and if it isn't as good for it when it's 45-50 outside over summer for me to throw it on that way I can easily put it in, I'm just confused as to what advancing the timing as well will really "do".

Advancing the timing makes the engine easier to start, and increases the combustion chamber temperature. Could possibly be bad for extended idling after the engine is warm.

On another note: switching to an electric fan has helped my winter warm up enormously. Even when your fan clutch is not engaged the fan still turns and moves air at idle, just this cold air blowing over the engine has a powerful cooling effect. With my electric fan, and some grille blocking, there is very little air flowing through my engine compartment. My truck is up to full operating temp (200F +/-) in around 10 minutes even when it's single digits outside. I don't think fast idle could have this much effect.

 

[laserjock]

Too much advance is ******* glow plugs. In the case of the high idle, would it matter? Don't know.

 

[LCAM-01XA]

Our truck was at first done without the diode and when the solenoids were powered with the engine nice and hot the pump would go silly and engine speed would fluctuate up-down big time - the engine would try to run away then the governor would catch it and defuel, then as the engine speed dropped way too low it would recover and revv up again. Annoying to say the least, possibly dangerous as well. Adding the diode fixed that issue, ended up with nice and stable hot high idle at around 900 RPMs.

This was not an issue while engine was cold or still warming up, only when it was up near its normal operating temp. Still have no idea why it was doing that...

 

[Dsl_Dog_Treat]

The diode blocks a 12v back feed into the timing advance system to keep the timing in check.

 

[no mufflers]

The diode blocks a 12v back feed into the timing advance system to keep the timing in check.

couldn't you use a relay and tie a switch into that.

 

[DaveBen]

You could but a single diode is much cheaper and easier. Less than $1.00 for the diode if you can find a Radio Shack.

 

[jwalterus]

or an alternator repair shop, or a boss snowplow service shop, they'll have one on hand as well

 

[OLDBULL8]

Any old piece of electronics like a radio, TV, usually has a lot of diodes on the boards. they look like this >l .

 

[LCAM-01XA]

The diode blocks a 12v back feed into the timing advance system to keep the timing in check.

Right, that's exactly it. What I meant was that I wasn't aware that too much timing on a hot engine can cause it to try and take off on its own like ours did. Well, for all I know, it could have been just an isolated incident with this individual pump only... But still, based on it I definitely wouldn't recommend skipping the diode when doing the high-idle mod.

 

[Dsl_Dog_Treat]

couldn't you use a relay and tie a switch into that.

You're still back feeding the timing system tho Elijah because the 2 power points converge on the IP.

 

[BrianX128]

You're still back feeding the timing system tho Elijah because the 2 power points converge on the IP.

Now if you used two relays... Haha that would be unbelievably stupid though. I found a radio shack today, just gotta stop tomorrow after work when they are actually open or tear into an old desktop pc I was throwing away anyways.

I will say I've used relays for many things that a diode would have been better for. I have 4 relays on my 150, I have a setup for two LED lights on a dimmer switch to light up the bed while at drive in movies so you can see your booze and nachos but not bother other people. But if I flip one switch on and another off then I have aux reverse lights under the bed along with the regular reverse lights and the dimmer lights in the bed I added as well that all come on when I put the truck in reverse along with the cargo light, so, seven reverse LED light fixtures. And I have a "go eff yourself " button in the cab where the fuel selector would be (it's a "Custom") that turns them all on while I'm driving to blind the **** out of the guy behind me tailgating me.

You must be registered for see images attach

Picture is missing one of my drive in movie dimmer lights I spliced into the one that's pictured in the bed. Between the 4 relays and the dimmer control in the bed the moral of the story is I have no idea now how I did any of it, I just know what to push to make it do what I want lol. And it sure is nice to have the anti-tailgater toggle switch though I think I've used it for that purpose twice? Haha. I don't drive this truck a whole lot to keep it mint but it's got plenty of "features".

 

[FORDF250HDXLT]

Brian, a relay is an automatic switch,rather than a manual toggle.a power source is used to turn the switch on for you (when you turn the ignition on) and so that it draws from a direct power source and doesn't overload a circuit.

a diode is just as simple.it's just a one way electrical valve.think of electricity current like water in a hose.if you place a diode upstream of something else also on the same circuit,the water,in this case electrical current can't go up that section of the circuit.

understanding what the devices are now,should clarify and simplify what needs to be done.