Land Rover/Low RPM Idle Engines

General Topics for configuring, operating and tuning the Megajolt. Also see the <a href="http://www.autosportlabs.net/MJLJ_V4_Operation_Guide">Operation Guide</a>

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jperkinson
Posts: 8
Joined: Sat May 31, 2008 7:02 pm

Land Rover/Low RPM Idle Engines

Post by jperkinson »

Hi= New to the MJLJ and EDIS system. I have begun sourcing parts for an install in my '73 Series Land Rover (2.25). I noticed that a few people on this site have also done this conversion on this truck.

Is there any concern about having such a low Idle RPM? Generally speaking, between 400-600 RPM? I read on here that the MJLJ can only read down to 400. Has anyone found this to be a problem?

Thanks
-Jim

hcp474
Posts: 9
Joined: Sun May 25, 2008 1:42 pm

Post by hcp474 »

I cant comment on how it will run, as i've yet to fully commision my re-build.

however reading down to 400 theoretically should not be a problem as the advance wont tailoff to a random number but work at the lowest rpm bin. it should be noted that the EDIS module will spark at rpms down to about 50 from my tests with a simulator (of the crank pickup).

Its the MJ unit that can't calculate the rpm from the pulse signals at low rpms, not the abilities of the EDIS module to produce the sparks.

David

jperkinson
Posts: 8
Joined: Sat May 31, 2008 7:02 pm

Post by jperkinson »

David-

Thanks for the reply. I'm by no means an expert, but i think I understand what you are saying...

The MJLJ 'thinks' that the RPM is at 400 when it is really lower. However this has no effect on the actual spark, which comes from the EDIS. The only implication is that no spark angle adjustments are made in this region by the MJLJ. So the EDIS fires at it's default 10' then.. or is there a setting in the MJLJ that covers operation in this region?

-Jim P.

P.S. - What's your rover? I've got a '73, ex-mod, ffr, 109

brentp
Site Admin
Posts: 6282
Joined: Wed Jan 24, 2007 6:36 am

Post by brentp »

If you're running the 3.2.1 firmware (Check help/about while the controller is connected and powered) the system will use the cell located in the upper left hand corner in the Ignition Map (lowest Load, lowest RPM) as the 'cranking rpm'.

Try disabling your fuel pump or disconnect your spark plugs so you can crank for an extended period of time- You should be able to verify the cranking RPM you specified- the configuration software should show this on the runtime gauge and should also agree with readings from your timing light.
Brent Picasso
CEO and Founder, Autosport Labs
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