User-defined output switches - what do you use it for?

Yvan · Post by **Yvan** » Mon Feb 18, 2008 6:17 am

I can not think of any use for the user-defined output switches. I guess I can use it for some sort of economy gauge, but I do not like lights flashing while I am driving. What do you use it for?

MartinM · Post by **MartinM** » Mon Feb 18, 2008 10:09 am

5 stage shift lights

Other uses are:
- intercooler water sprays
- in a MAP MJLJ program them on MAP (rather than, as most people seem to use, RPM) to get as set of "boost lights"
- ....and I'm sure there are others

Salamander · Post by **Salamander** » Mon Feb 18, 2008 2:38 pm

Put a fuel rail with an additional injector when these poor air-fuel in a system carburated

Post by **brentp** » Mon Feb 18, 2008 5:35 pm

Here are a few possibilities:

Shift lights
Over boost indicator
Inter cooler sprayer
Inter cooler fan
Variable intake system actuator (Toyota TVIS)
supplemental injector control (using a 'cold start' injector)

Yvan · Post by **Yvan** » Mon Feb 18, 2008 7:20 pm

I guess I'll have to wait until temp controll is added, I can not use anything of what you mentioned (I have normally aspirated LPG powered BMW M10 engine). Shift lights yes, but I do not need that...

Thank you for responses.

britlude · Post by **britlude** » Mon Feb 18, 2008 9:26 pm

you don't HAVE to use them, they are just there for those that have uses for them!

for me, I just use them to drive LEDs as a basic rev counter on the front of the MJLJ (which is inside the car on the firewall!) it gives something for the passenger to look at when they are too terrified to look out of the screen any more! and gives me an easy indication that the MJLJ is working ok!

aviwolf · Post by **aviwolf** » Sat Mar 01, 2008 8:15 pm

Hi,

I was thinking on using the trigger for the following:
1) Nitrous window (I'll need two triggers for it)
2) Fuel pump cut out when engine is not running
3) A/C cut out when on full load (I need the A/C first

)

MartinM · Post by **MartinM** » Sat Mar 01, 2008 8:36 pm

aviwolf wrote: 1) Nitrous window (I'll need two triggers for it)
2) Fuel pump cut out when engine is not running
3) A/C cut out when on full load (I need the A/C first )

1) is good if you can do the external circuitry needed to get a "window"
2) won't work - the outputs switch at 500rpm minimum so they can't tell the difference between an engine cranking and not running - which is rather important for controlling a fuel pump

3) sounds cool...(pun intended!)

Martin

Yvan · Post by **Yvan** » Sun Mar 02, 2008 5:31 am

I think that a/c cut out at full load does "sound cool" but I don't think it's useful. MJLJ will cut out a/c every time you hit full throttle. Depending on your engine size and driving style that might be often, and not too good for the a/c compressor.

Post by **brentp** » Sun Mar 02, 2008 6:25 pm

Very cool! So far I've been impressed with all of the creative ideas. Like a wrench in your tool box, it's use will be self apparent when you have a problem to solve.

Yvan · Post by **Yvan** » Thu Mar 06, 2008 8:10 pm

If I set one of the output switches at rev limit, and use it to power off ignition coil (with a relay), wold that work? Or would the engine just die?

I actually do not need rev limit, but I am curious

MartinM · Post by **MartinM** » Thu Mar 06, 2008 10:31 pm

You could - but then all the ignition theory anoraks will come along and tell you that you shouldn't hard cut the ignition coil power at random times compared with the coil charging times as you will get random sparks at completely the wrong timing, which at high rpm can be a Very Bad Thing...

...and that relays are unreliable

...and xyz

...but I'm sure it will work

Yvan · Post by **Yvan** » Fri Mar 07, 2008 5:18 am

MartinM wrote:You could - but then all the ignition theory anoraks will come along and tell you that you shouldn't hard cut the ignition coil power at random times compared with the coil charging times as you will get random sparks at completely the wrong timing, which at high rpm can be a Very Bad Thing...

I didn't know that

And it did sound too simple.

I actually do not need rev limiter, I rarely ever pass 4000 rpm, I am just trying to find something useful for these switches

aviwolf · Post by **aviwolf** » Sat Mar 15, 2008 3:48 pm

MartinM wrote:
aviwolf wrote: 1) Nitrous window (I'll need two triggers for it)
2) Fuel pump cut out when engine is not running
3) A/C cut out when on full load (I need the A/C first )
1) is good if you can do the external circuitry needed to get a "window"
2) won't work - the outputs switch at 500rpm minimum so they can't tell the difference between an engine cranking and not running - which is rather important for controlling a fuel pump
3) sounds cool...(pun intended!)

Martin

Thanks for the info about the fuel pump cut out. I can use the starter circuit to run the pump while cracking. Since it is a carb engine, the fuel in the bowl could be enough. What do you think?

DannyP · Post by **DannyP** » Sun Mar 16, 2008 4:50 pm

On a carbureted car you would need an electric solenoid on the main needle, very hard to do. This would be similar to the idle cutoff on the VW Beetle. If you had multiple carbs you would need one for each carb throat. There is enough fuel in the float bowl to run the car for at least a few seconds, which is not what you want for a fuel cut. You need an immediate reaction, no delay. FI cars have higher fuel pressure with no reserve "bowl" to draw from, which is why an immediate cut of the pump results in an immediate loss of fuel.