Dual fuel

[mdh]

I run a dual fuel vehicle.

I there anyway to get MJLJr to run two different maps dependent on what fuel I'm running?

If not, can I build two MJLJr's and switch between them? Will they work ok if theyre both connected to the same Edis, vacumn source and coil packs?

[brentp]

unfortunately, there isn't enough memory in the processor to accomodate two ignition maps. It might be possible to reduce the size of the map and allow enough room for two, though. Of course, that would require custom coding in the processor.

For two controllers you'd have to isolate the SAW output going to the EDIS controller. you don't want to confuse the EDIS module with SAW signals coming from two different controllers. The tach signal is another line you'd have to isolate.

[Paratime]

Although there isn't memory for a complete second map, is there space to extend the map past the current 10 RPM settings? I am going to be using the MJLJ on a large displacement, high compression engine, (455cid 10.25:1) and I'm too cheap to buy premium. I have been running OK on a distributor I custom curved, but it is VERY sensitive to timing changes of only one or two degrees over a couple hundred RPM.

[brentp]

I've thought a bit about this, and kind of smacked myself in the head for not thinking of this.

There's enough flash memory to provide at least two different complete configurations. Probably what you'd end up doing is wiring a switch to one of the unused ports on the microcontroller, then it's position would determine what area of memory it's currently working with; Map 1 or Map 2.

Not sure if it would be feasable to switch it while driving, but it would certainly work if the unit was power-cycled. As far as configuration goes, it would act like two different controllers- you'd see the settings for one mode or the other depending on the position of the switch.

I'll give this some more thought.

Paratime, it might be possible to make a custom version of the firmware to bias more RPM resolution over MAP sensor resolution. it would take quite a bit of testing to make sure it works correctly, though.

-Brent

[ohecht]

I believe that Megasquirt "interpolates" between map entries to determine values in between defined points on the fuel map.

Does MJLJ do this as well, or does it just use the closest value?

Thanks,

Olivier

[brentp]

Hi,

Interpolation support is scheduled for a future firmware release- when it's ready you'll be able to update your existing firmware.

Thanks,
Brent

[mdh]

Hi Brent

The switchable map would be a great idea - any idea whe/if it'll be ready for testing?

[MartinM]

It's already there - and has been for a year or so

It's a standard feature of the current V3.2,1 software - see
http://www.autosportlabs.net/MJLJ_V3_ve ... E_3.1.0.29

[brentp]

No kidding! Did you just crawl out from under a rock??

The software configuration for this feature is covered in our operation guide.
http://www.autosportlabs.net/MJLJ_V3_Op ... igurations

[mdh]

I kinda 'lost' the site for a while while travelling and have only just refound it!!

Good job on the new site btw.

[mdh]

I kinda 'lost' the site for a while while travelling and have only just refound it!!

Good job on the new site btw.

[brentp]

Thank you. 2008 we will load in more and more great information.

It sounds like you will need to update your firmware, that process is documented in the wiki as well. Let us know how it works for you.

Regards,

[mdh]

Thanks for the pointers guys!

Will my old hardware run v3.2.1?

[brentp]

If you have the V2.x hardware then the firmware you would upgrade to is V2.8.x. It's important you flash the correct firmware to your hardware.

The upgrade guide is here:
http://www.autosportlabs.net/3.2.x/2.8. ... rade_guide