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MegaJolt - Pros Cons and General MJ Discussion thread


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This thread has been split from a thread initally started on the For sale thread.

The thread evolved - rather than a "For Sale" it developed into a tech thread of the advantages and differences over MS to MJ or the other way around.

the For sale thread is here :

http://forums.lr4x4.com/index.php?showtopic=33191&st=0

This Thread is here around the Megajolt system, as such the Megasquirt system thread may equally be usefull reading :

http://forums.lr4x4.com/index.php?showtopic=15317

Enjoy !

Nige :)

Hi RangeyRover,

I have read on pirate4x4 your install of the Megajolt and that was pretty interesting. I believe now you are plenty happy with the performance and water resistance ?

There is just one thing I would like to double check.

On your running install, how do you feed the LUCAS ECU with "engine running data / dizzy pulse", which on stock design was going from the coil to pin 39 of the LUCAS 14CUX ?

Are you indeed using the 5 diode arrangement ?

Thank you very much for your kind answer in advance.

Erik.

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Not wishing to pour cold water on this but having had a Megajolt system on my V8 (and yes it is waterproof if done properly with the FORD Plug caps etc etc) it is a great system without doubt. :)

With some work on the spark map you can find you engine runs very smoothly,

and even LPG as an optional MAP and not as often is the case of LPG'd V8 a bit of a bodge.

BUT,

and its a HUGE ONE,

it still means your running the horrible AFMs and ECU and other dreadfull Lucarse electronics such as the resistor

pack on Flappers etc etc etc with the Megajolt fitted, or worse a set of carbs bucket with a hole in it..but a clever Spark system

On the ECU EFI side you have (as I have) a tuned engine the spark from the MJ can be so much stronger it makes the V8 then run weak,

and you play hunty lurchy times when crusing, too weak and you risk possible serious damage,

the one answer is to either find and fit the JED Adjustable ECUs (a bodge)

or pay out for a Hedgehog chip EPROM for a Hotwire (£s cost is higher than a FULL MS Install)

Either way you have the hideous Lucas AFMs and ECUs all the faults and reliablity issues on top, fault finding is still a F nightmare

Even if the ECUs don't run weak they won't be running your engine at anywhere its potential the tunablity of full Megasquirt (Basically a

MJ spark and then a similar Fuel system so controls Spark and Fuel) FULL Megasquirt is hugely more flexible advanced and

for only a few £s more. ? ....Oh and a PC based program to see what your engine is doing, and then the ability to tune the

ECU in both spark and fuel FOC as are all upgrades :).

I did the MJ route as a test on my V8 prob now near 3 years ago, its good,

but compared with MS its not worth fitting as for just a tad more you can Loose the AFM ECU half the sensors and wires,

and repalce the entire lot with a system that you wish you'd found yonks ago

I have gone from a JED 4.5 Race V8 with adjustable ECU Jag injectors Resisitor pack Flapper Loom and

AFM and nothing but troubles and when it did run it was not happy and sweet and smooth, part the fact flapper

is a horrible system (Hotwire is not that much better) and the tunning of the engine making it piocky...

Now, walk up turn the key and it starts warms up as the revs come down to a smooth tickover,

the engine even in it state of tune suprises most as they don't get the clues that you normally do on a race engine,

its tractable and smooth and silky, just a touch of cam can be spotted.....on a factory std motor the differences are simailrly as dramatic,

you wnat real perfomance, then you tune the MAP to give it, you wnat LPG - do it on a spare map,

want a crusing fuel enconomy map, - it can be done (within the confins of it still being a V F 8 :lol:)

Bear in mind also that MJ and MS do both use say Ford Coil Packs and EDIS8s, but they have very much gone seperate roots now,

and if you fit MJ its not compatible or 2upgradable" to Full MS, you'll use the Packs trigger wheel and VR and Edis,

but ECU wiring etc is start again time, so be sure which route you go is the one you wnat long term.....

BOTH are a huge improvement over the standard clockwork spark generator on Rover V8s tho :lol:

Nige

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I don't use the ECU/AFM on mine (well, except the stepper motor control), as it's 99.999% of the time on LPG, the current *petrol* setup doesn't scare me THAT much that I feel the need to replace it...

This is the solution for me, I have to say, I would feel rather agrieved spending out on full MS and only using it's full capability 0.001% of the time...

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Horses for courses.

If you have modded the engine then you will need more fuel.

You may need more fuel with this set up.

I'm going to fit a wideband o2 to mine to investigate if it runs lean.

Then I will be able to give a definitive reply.

I do not want to give people something that will cause a problem

I must say that I don't think that Megasquirt is a few pounds more.

The ecu price alone is nearly double at £200 from glens garage.

(I don't know what fridge charges)

Then you need the rest of the kit I have listed anyway, EDIS 8 coils etc.

I AM NOT denigrating what Megasquirt is, its going to find its way onto my motor soon, and I like it!

But sometimes doing things in stages is the answer.

PS all my Lucarse stuff still works, so making me reluctant to change it out, and easy for me at least to still get parts for.

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Technically the only bit you're changing out from Lucas is the ECU itself, the airflow meter is redundant.

You're right, horses for courses though - for those on LPG most of the time there's not much point having MS (until someone wires one up to a sequential LPG kit to fire the LPG injectors).

For an MS ECU built, modded for PWM idle & EDIS I charge £250 currently.

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Technically the only bit you're changing out from Lucas is the ECU itself, the airflow meter is redundant.

You're right, horses for courses though - for those on LPG most of the time there's not much point having MS (until someone wires one up to a sequential LPG kit to fire the LPG injectors).

For an MS ECU built, modded for PWM idle & EDIS I charge £250 currently.

quick question why did you quote me £650 odd quid when i pm'd you a price request?

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so MegaSquirt won't work with LPG? :(

It COULD, just hasn't been to my knowledge yet.... Don't really know what kind of feed the LPG injectors need, that would be a starting point, but this is dangerously OT, so I'll STFU :P

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so MegaSquirt won't work with LPG? :(

Well, the usual setup is to run the petrol injectors with MegaSquirt, there's no reason why you couldn't connect LPG injectors to it (or even both and run staged / switchable injection) it's just that no-one's done it yet.

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so if i were to fit megajolt to my 3.5 on carbs do i just adjust the mixture to make it run richer?

or am i stupid and completely missing something? :)

Nope your not being stupid

If you wnat to keep carbs you may find that your ok mixture wise, if not richen and or up needle sizes, but you may be ok as carbs are more hit n miss than efi and efi was often (esp for USA Market) brought in for economy (read weak as poss :lol:), so carbs prob you'll be fine

and waterproof :) (well, Dizzy wise) :lol:

Nige

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Well, the usual setup is to run the petrol injectors with MegaSquirt, there's no reason why you couldn't connect LPG injectors to it (or even both and run staged / switchable injection) it's just that no-one's done it yet.

So for a V8 on LPG and Petrol, it would have to have two sets of injectors? and then switch them? or could you just run on LPG and MS run just the one set of LPG injectors?

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I would like to have another setup of you but this time it will have to be the MS setup.

I would like to say to you all that Rangy Rover fitted a MJ kit to my 3M Challenger and it did make a big differance to the way it started and ran even through water. I even jetwashed the engine when i got home from a days offroading and it still ran fine.

So don't knock it till you try it.

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So for a V8 on LPG and Petrol, it would have to have two sets of injectors? and then switch them? or could you just run on LPG and MS run just the one set of LPG injectors?

Well you kind of need two sets of injectors for two different fuel types as trying to run two fuels along the same fuel line would be problematic. As I said, sequential LPG systems add a second set of injectors for LPG so the hardware's already there. MS could run just LPG, just petrol, or both depending how you set it up.

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so MegaSquirt won't work with LPG? :(

MegaSquirt works very well with LPG and you DO get more performance. As it has been said before i will be brief.. with MS you can set the set up the engine to run sweeet on petrol then switch to the 2nd spark map that is maybe 2deg more than the petrol map and have the fuel map set to 0%. Because the engine is set up to run at its best on petrol it should run very well on LPG as all your changing is the fuel and timing to suit. Using the "cooker ring" set up it will also run without MS as the EDIS will fire at 10btdc but with no advance so will get you home if you go too deep.. :ph34r: As for LPG injection run by MS that is something in R&D at the moment but will happen as i know a man with the right injectors but the price for each one..... it will happen... some how. ;)

Jeff

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So don't knock it till you try it.

Absolutely couldn't agree more :)

Have tried it (loved it) and I won't knock it :)

I was just making the point that there is both MJ and MS out there, frankly I was SO impressed with MJ I went the next stage to full MS

I know people who have full MS but only run the fuel, and others that only run the spark and fuel to come,

but I think as to if you go MJ over MS thats not an "inferior" system its a DIFFERENT one, but for all to be aware of BOTH.

And I KNOW how happy Mr RangetRover is with his MJ - Hell I helped him with his spark map :)

As I said if MJ does what your after BUY IT, its superb,

but be aware you could have spark AND Fuel but you may not want that,

however

buying MJ then think of (as I did ) going full MS is an expensive route as they are different even if they share parts -

chose once ......and be happy :)

Nige

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[thread hi-jack]

Of course, if you fitted a stinky diesel, you wouldn't have worry about all this ^^^^^^^^^ nonsense.

Less bunnies and birdies will pop their clogs as you chug by, you'll get more mpg, and be able to go through really deep puddles with no more modifications than a bit of B&Q drainpipe attached to the air intake with some gaffer tape

[/thread hi-jack]

Les :unsure:

:lol:

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Hi RangeyRover,

I have read on pirate4x4 your install of the Megajolt and that was pretty interesting. I believe now you are plenty happy with the performance and water resistance ?

There is just one thing I would like to double check.

On your running install, how do you feed the LUCAS ECU with "engine running data / dizzy pulse", which on stock design was going from the coil to pin 39 of the LUCAS 14CUX ?

Are you indeed using the 5 diode arrangement ?

Thank you very much for your kind answer in advance.

Erik.

Yes Erik,

I am exactly as shown there. I will post it here soon for everyone.

RR

modwiring2oj4.png

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I have fitted MJ to my hotwire V8 and would like to add a few points which might prove useful to those thinking of going down this route:

I have no problem with the 14cux or hot-wire AFM (my previous rich running which was down to a loose wire).

Running on LPG 99% of the time, I have no need of MS and to be honest - the thought of trying to sort out a fuel map is a little daunting to me.

MJ runs dual ignition maps and switches in an instant (just like MS) so is perfect for LPG. My MJ map-switching is controlled by a takeoff from the (automatic) LPG switching controller.

The LPG map is not just a matter of adding the same advance everywhere - see this site for a good starting point. (I don't currently have a tested LPG map sorted since the car is not MoT'd and can't get to an LPG supply)

My setup (with B&Q snorkel) appears to be totally waterproof - tested by throwing a plastic box full (about 4 gallons?) of water onto a hot engine at tickover. Never even stumbled.

A good source of reasonably priced bespoke silicone leads with EDIS style heads and waterproof plug covers is Fastlane Auto - every lead made to my exact specification and delivered in three days! I went for these i) Because my old leads were shot. ii) Because of my coil-pack location and iii) Because LPG needs the best spark it can get.

I run a MAP setup with the vacuum signal taken from the rear of the plenum (as RangeyRover suggested somewhere - I think on the MJ forum . This really made a difference to the pickup off idle.

On the common-earth point - suggested above - mine wouldn't spark at all until I had connected all earths (including most importantly the signal cables' shielding) to a common earth. I also feed everything (like RangeyRover) from a common (fused) relay controlled by the ignition.

I use the 4+1 diode pack to provide the signal to the ECU which I feed into the line that goes from the original coil. This lead (the one from the coil to the ECU) already has the required resistor in it to prevent too many volts hitting the ECU. My 4+1 diodes are mounted on a little additional board in the MJ case, but if I was to do it again I think I would make them in-line. I also use shielded cable for this lead - probably not necessary, but I thought that I would do that for all 'signal' leads.

The trigger wheel setup can be economically obtained by clamping a Ford Transit trigger wheel on the back of the harmonic balancer like this: gallery_3439_602_62249.jpg

HTH

Rog

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RR, Rog,

thank you both for your emails. These informations/feedbacks are really valuable :rolleyes:

I am waiting for parts to arrive over here (far from UK) and will start to play with all that soon I hope... only difference being I will start with the ignition side only of the 3.9 V8, just as if I was Megajolting, but this is just a matter of free time, and will be later continuing with the EFI side as I will be using a Megasquirt ECU in fact.

Thanks again

Erik.

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