PROBLEM... Is this limp home mode???

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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colinu
Posts: 3
Joined: Wed Mar 18, 2009 11:56 am
Location: Nr Edinburgh, UK

PROBLEM... Is this limp home mode???

Post by colinu »

PROBLEM SOLVED (see 3rd post in this thread)

Hi,

I've been running a MegaJolt v3 on my 1380cc Mini for the past few year. Been a dream... until this morning's drive to work. It performance was lifeless... felt like limp home mode to me :(
Over lunch I hooked up my laptop/configurator to the MJ. The map is still present, but when I fired her up I see that the actual timing advance figure (bottom right 'gauge') does not track the actual advance described in the map table... instead it is bouncing in the 5 to 7 degrees range.
Hmmm.
Is this the sign of a fried MJ, or more likely that I need to chase down a wiring issue?
Any thoughts/advice would be greatly appreciated.

Cheers,
Colin.
Attachments
advance not matching/tracking map table
advance not matching/tracking map table
mj_issue.jpg (169.56 KiB) Viewed 7002 times
Last edited by colinu on Sat Apr 16, 2016 5:22 pm, edited 1 time in total.

colinu
Posts: 3
Joined: Wed Mar 18, 2009 11:56 am
Location: Nr Edinburgh, UK

Post by colinu »

OK it's looking like the MJ unit is the problem. If I disconnect it (i.e. EDIS definitely operating in limp-home mode) then the engine idles and revs far smoother. I checked/traced all the wiring and could not find any evidence of shorted, or broken wires, or bad connections. So gut feel is telling me I need to replace the MJ unit :(

colinu
Posts: 3
Joined: Wed Mar 18, 2009 11:56 am
Location: Nr Edinburgh, UK

Post by colinu »

PROBLEM SOLVED

So I was about click the 'Buy' button an order a replacement MJ, but decided to hook the laptop up one last time to see if I could find the problem. I'm glad I did! ...

Turns out the Advance Correction data had been loaded with random garbage! Unfortunately I forgot to take a screen capture (pic below is what it should typically look like if good), but what I saw was that the correction values were large randoms such as -220, +44, -62, etc, plus the peak hold value was something up in the 37000 range. How that occurred I don't know (I've never touched that data in the past). Returning everything to zeros (i.e. disabling the advance correction) and everything is working OK again :)

I do have two observations though:
  • - The Advance Correction is not part of the saved map... and those values won't be wiped/overwritten if you load in a new map (or certainly not on my v3 hardware using rev v3.3.2 firmware and configurator)
  • - Just before this problem happened I got an error message from the configurator... something along the lines of "Configurator not compatible with this rev of MJ firmware". I closed down, reconnected and didn't see it again. I'm wondering if there had been a bad comms session when opening the configurator s/w and the MJ hardware interpreted it as 'go change the Advance Correction values'???
Anyway, all is good and my Mini is back terrorizing my favorite roads :)

Cheers,
Colin.
Attachments
Example of good data set (from operation manual)
Example of good data set (from operation manual)
Mj_advance_correction.jpg (59.78 KiB) Viewed 6987 times

brentp
Site Admin
Posts: 6274
Joined: Wed Jan 24, 2007 6:36 am

Post by brentp »

Wow, good job figuring it out!
Brent Picasso
CEO and Founder, Autosport Labs
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