Going back to MAP

david jenkins · Post by **david jenkins** » Sun Jun 26, 2016 6:30 pm

Hi!

First of all - I can say with some pride that I've now been running my Megajolt for almost 10 years on this car! It's been so reliable that I haven't had to give it much thought over the years.

My MJLT v3 is on firmware 3.2.1 - originally I ran it with a Weber DGV down-draft carb, and built it for MAP. Later on I converted it to TPS by adding the extra components and cutting R4 (270R) to isolate the MAP sensor.

Now I want to go back to MAP, having decided to ditch the bike carbs and go back to a single Weber DGV. Can I just replace R4 to use the MAP sensor? The TPS wiring will be disconnected, of course. I've looked at the schematic and I can't see that the TPS components will have any effect on the MAP signal - am I right?

Many thanks,
David

parky1972 · Post by **parky1972** » Wed Jul 06, 2016 7:22 pm

Hi David.

Yes, as I understand it that is correct for both v3 and v4 controllers.

You may need to reflash the chip.. I'm not sure about that..
Try it,if it doesn't work. Try the reflash.

Jason.

Post by **brentp** » Thu Jul 07, 2016 10:47 pm

You should just be able to wire in the map sensor since it's connected to the same processor line. Recommend re-flashing the V3 firmware as well!

david jenkins · Post by **david jenkins** » Sat Jul 09, 2016 6:03 pm

Many thanks!

I'm currently trying to refresh my memory regarding the way MJLT is configured...

It's been working so well I've forgotten how to set it up!

I've changed from TPS to MAP in the configurator, checked the 'normally aspirated' box, and saved it back to the unit. However, it still looks like it's working in 2D instead of 3D - the 'currently active cell' is staying in the top row, rather than going up and down the grid.

I'll keep playing though - while trying to run the engine with a new carb and struggling to keep it running, I heard a nasty ticking noise that sounded like a bad tappet adjustment, or an arcing HT lead - in the end it turned out to be a blown exhaust gasket puffing gas out every other revolution! I'll carry on with MJLT once I've replaced the gasket and put it all back together again.

Are there any example maps around for a MAP setup? Not for use, just for reference. IGNORE: I found one...

Cheers,
David

Post by **brentp** » Sat Jul 09, 2016 6:23 pm

Hi David,

I would definitely flash the stock firmware back on - this will restore the load calibration to match the MPX4250AP map sensor.

Glad you're making progress!

david jenkins · Post by **david jenkins** » Mon Jul 11, 2016 12:45 pm

I flashed the latest firmware, and the MAP response is now working again.

All I have to do now is to get the carb tuned properly...

Many thanks for the help,
David