L31 Extreme Budget Build

[Supercharged111]

You cranked the modulator all the way down? I'm not done messing with the Monte myself. With the 5000 1-2 WOT shift the part throttle is a little late now. But I'm nowhere near bottomed out.

 

[L31MaxExpress]

You cranked the modulator all the way down? I'm not done messing with the Monte myself. With the 5000 1-2 WOT shift the part throttle is a little late now. But I'm nowhere near bottomed out.

I cranked it in 2 turns. Not all the way. You can crank them all the way in and can even remove the adjustment screw if you want backing it out. Engines that pull good vacuum tend to stack shift at light throttle.

 

[Supercharged111]

I cranked it in 2 turns. Not all the way. You can crank them all the way in and can even remove the adjustment screw if you want backing it out. Engines that pull good vacuum tend to stack shift at light throttle.

2 turns from falling out? I don't know if these have a baseline setting a stockish engine would start at.

 

[L31MaxExpress]

2 turns from falling out? I don't know if these have a baseline setting a stockish engine would start at.

I cranked it in 2 turns in from the base setting. The base setting is adjusted to match the everyday normal GM modulator. 2 turns clockwise increases the tension on the spring making it harder for vacuum to move the plunger thus delaying the shifts and making them slightly firmer at part throttle.

 

[L31MaxExpress]

Think of modulator similar to as if it were a vacuum referenced fuel pressure regulator. Now make the zero vacuum fuel pressure fixed and make the vacuum referenced pressure adjustable. That is how the modulator works. It has X amount of base pressure without vacuum on it. It will always have that same base pressure without the vacuum line on it. The adjustment screw is on the vacuum reference side. The screw controls how much the base pressure falls in relation to increasing vacuum. If you have the screw all the way out, the spring pressure is the least and thus vacuum can more easily reduce the pressure. As you increase the spring tension by turning the screw in, it raises the spring platform, putting more tension on the spring and it takes more vacuum to reduce the pressure.

 

[Supercharged111]

Oh its theory of operation isn't lost on me, I just wasn't sure if there was a rule of thumb as to where one generally starts.

 

[L31MaxExpress]

Hit this project hard the past few days.

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[L31MaxExpress]

Wired up a temporary harness for only the starter, alternator, proflow and fuel pump. Then this happened.

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Took a few screenshot of the Proflow 4 data while it was running.

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[Supercharged111]

What do the VE and timing maps look like?

 

[L31MaxExpress]

What do the VE and timing maps look like?

What VE map? The timing map is like 5 values. Idle advance, advance start rpm, total advance, rpm for total advance thing how many degrees of vacuum advance. The fuel map pre-loads with the startup wizard based off the displacement, injector size and cam duration/idle vacuum.