The megasquirt forums are filled with nauseating amounts of trivial information, so lets get right to the point.

I want a megasquirt board to control EFI only. i dont need EDIS or distributorless complications. i want to keep the factory Dizzy, amp, vacuum advance, etc. All i want to do is to control fuel.

its clear that im not the only person on this forum who is desperate to be rid of BL's fossilized EFI system.

so lets combine what we know and figure out what the best way to megasquirt our V12's is!


i dont want to build a board. im prepared to pay the extra $100 or so for a complete ECU.

so what software do we need for EFI? MI, MII, or MIII?

whats the best way to wire up the system? the M harness is 12' long and our cars are 17' long. should we relocate the M board or leave it in the trunk?

the MI system appears to pulse injectors in 2 banks. does that mean the old system of 4 groups of 3 needs to be 2 groups of 6? will this effect performance?

will the factory injector resistor work for the M system or do we need something else?

will the factory IAT and CTS be ok for the new application?

will the factory or mustang upgraded TPS be ok?

will the single wire O2 sensors work with M?


if anyone knows of a complete kit for most engines that is easily compatible, please speak up!

 

I feel very sorry indeed, but in spite of the fact that my English is good enough, or at least this is what I believe, I don't understand what are your talking about. With all this abbreviations, really I don't find my way, and, taking into consideration that I am very much interested in my XJS convertible, V12, 1991, pre facellift, I allow myself to ask you to be so kind as to give me an indication on this matter.
Thank you very much in advance and, please, excuse me.

 

Santos, he is talking about an aftermarket computer to replace the factory Jaguar computer. The one that controls the fuel injection on a v12. Megasquirt is the name of the company that makes the computer and it has several different models, such as MI, MII, and MIII.

 

EFI: electronic fuel injection.
CTS: coolant sensor
IAT: intake air temperature sensor
TPS: throttle position sensor.
M: megasquirt.
ECU: engine control unit.
' = feet
" = inches
O2 = oxygen
EDIS: electronic distributorless ignition system.
Dizzy: distributor
Amp: amplifier
BL: British Leyland.
MI: megasquirt 1
MII: megasquirt 2
MIII: megasquirt 3

 

OSIJMMPWISHMTWCM= Oh **** I Just Messed My Pants When I Saw How Much This Will Cost Me

 

That one threw me for a minute when I read your first post, it's been a long time since I thought of BL!

 

I thank you very much for your kind answer. Believe me, but I was astonished not being able to understand a word. Now I feel much better and I take due note of your information. From now on I will investigate this matter.
Again, thank you very much.

 

M90 the MS is a cusomisable ECU that can be bought from basic to fully configured. The major differences between the MS11 and MS111 are that MS111 uses mostly surface mount technology, not sure of the MS1.

They can run upto 8 injector drivers, they are configurable for either high or low impedance injectors. They can run internal Ignition drivers, or be used with Fords EDIS or GM DS systems.

It does take some knowledge of ECU/EFI systems to build one. I think your idea of buying one complete is best. Even though I am a qualified electronics tech I bought one compete as by the time you buy the testing rigs it is cheaper to buy one already built.

 

See answeres in Italics

I want a megasquirt board to control EFI only. i dont need EDIS or distributorless complications. i want to keep the factory Dizzy, amp, vacuum advance, etc. All i want to do is to control fuel.

This would be an almost pointless exercise the main benefit is the ability to control ignition timing the Lucas ECU does ok with fuel. It has been working for 20-30 years.

Although setting a MS up with fuel only get it running then migrate to electronic ignition. You can keep the Dissy this is what the Marelli system does.

i dont want to build a board. im prepared to pay the extra $100 or so for a complete ECU.

Yep excellent choice

so what software do we need for EFI? MI, MII, or MIII?

The guy in South Africa has his XJS running on Version 3.0

whats the best way to wire up the system? the M harness is 12' long and our cars are 17' long. should we relocate the M board or leave it in the trunk?

I would move the ECU into the passenger footwell (this is where the Marelli ignition ECU is located) then the harness will be more than long enough.

the MI system appears to pulse injectors in 2 banks. does that mean the old system of 4 groups of 3 needs to be 2 groups of 6? will this effect performance?

MS can have upto 8 injector drivers

will the factory injector resistor work for the M system or do we need something else?

Probably not, the MS uses current limiting resistors for low Z injectors you can specify this when ordering.

will the factory IAT and CTS be ok for the new application?

Don't know would have to ask the question of DIYAT

will the factory or mustang upgraded TPS be ok?

Most likely yes , I'll look up the table when I get home.

will the single wire O2 sensors work with M?

I would say yes, but these are not a big deal to replace

if anyone knows of a complete kit for most engines that is easily compatible, please speak up

No kit for the V12 would be a complete custom.

 

well its about time M90,course you cant get your jag stuff working properly!

for those who can afford it.

here are some other companies that make EFI ECU systems.

Haltech efi
Motec efi

Fast efi
Microtech efi

SDS efi

BUT all of them will require wiring harnesses for the V12 Jag engine, they can supply most sensors and plugs, along with wire, but you would still have to mount things and wire everything up.

remember most of them will have to be PROGRAMMED, if M90 is having trouble with his stuff, he will have a circus hooking it all up and then program it all.

on a lighter note, recent designs can actually program themselves by using a wideband sensor, and the other sensors, like air temp, coolant temp, rpm , TPS and most important manifold pressure!

now that said,, the system properly setup,, is one of the most satisfying things you can do to any engine!

as most here know i use SDS(its a little dated tho), still works good!

but i use a MICROTECH system on my Mazda rotary, very rewarding, it has a set of secondary injectors that come on when HI-BOOST reaches a programed point, to add extra fuel for detonation control at hi-rpm!

 

Add to that WOLF 3D

There are a couple of XJS V12's here in Aus running the WOLF. An expensive option though.

 

very good warren, probably others also, but dont come to mind!

what would be important in any old car would be replacing all the old wiring and swtiches, relays etc. the list can be endless.

i just went thru a PITA for my directional switch, old broken wires, corroded contacts, took two bad switches to make one useable piece, a 33 yr old switch i guess i cant complain, but i had a few unique phrases for it!! hehe

 

im nearly prepared to agree with you, but my Lucas ECU cant even handle fuel, and from the Mforum testimony ive read, it seems most XJS owners switch to M for this very same reason. some stupid ghost in the machine and everyone is clueless as to what it could be.
a month later and still no one has a clue.

and i appreciate ronbros smart *** attitude. funny ron, cause didnt you just say,

?

 

It that the fault of the ECU or wiring?

Unless the ECU is faulty usually caused by wiring faults all of the issues are wiring related. If you replace the Lucas ECU with the MS and do not replace the wiring you will still have the same issues.

Unless you intend to go electronic ignition I would save your money and just re-wire the car.

 

well i was also interested in the tuning aspect of the megasquirt.

 

Most of any power gain is going to come from ignition timing as well as fuel - I don't think you will see much if any gain from fuel only tuning.

 

M90 why do you think so many jaguars end up in the junkyard, its the money it takes to get one running right.

a lot of times,for some people ,its less stress to scrap the car,or like just give it away, like in 2010, a guy walked up to me, said got a 1975 XJ12C, coupe, manual shift, and it dont run,, wife says its going to junkyard,just to get it out of back yard!!!

so i ended up with it, for tow charges.

yeah, i got it running, only because PO s mechanics, big Jaguar shop in Dallas TX, could not make it run they replaced everything but the com[plete wiring harness, and associated GROUNDS, does that sound familier???
by that time they burned out close to half the newly replaced parts! screwin around with everything.

i turned it around 3 days after i advertised in a car mag. for a good profit!

it went to a car lover in Maui HI. and he loves it,shipping was almost as much as it cost him.

a lot on this forum just dont get it,, they are only old cars, a hobby , something to keep them occupied, not many V12s for DD, in todays world,gas prices they dont really make a lot of sense, YA just got to like em.

my Buick gets much better mpg than Jag, and way faster , sorry to say.

and my cars are show queens, and all of them fit a different demographic,(generations).
what excites one, dont do anything for the next guy, its fun watching them tho!

 

i do some pix of my daily driver,DD.

but id be laughed of the forum, someday maybe!!!!!

(hint, it gets 45mpg, on used veggie oil, i get for free)

Ron

 

You haven't yet determined the ECU is the source of all your problems. Fix your problems first, THEN think about custom building an ECU because if you don't, you'll have everything screwed up and you'll never know if it's the car, wiring, sensor, or the brand new ECU that you're never able to work the bugs out of.

Check your ECU grounds!

Also you mentioned you had all your sensors jumpered...reconnect them and put in a NEW CTS - they only cost $20. Buy two. I'd recommend a new IATS just for good measure, but they are around $120 and I don't think it's justified yet.

You need to get your car running first before you modify...that means getting it back to STOCK because there is a set way this car was meant to run, and 99% of the parts to do it are still on the car. Get it figured out first, then you can add variables from there. Nothing you've been through yet points towards the ECU, and you've already swapped that out with no change in behavior anyway. Check the ECU ground then work elsewhere.

I really do feel bad for you, I can't imagine how frustrating this must be for you. But if you try and put in a custom-built ECU you will NEVER, EVER have this car running, you will end up dumping off a non-running car to ronbros for free, and you will have LOST the cost of that ECU and all thr hours you put into it.

We can work through this...keep feeding us info and keep taking our suggestions.

D

 

AW come on we'd love to see the DD at least it is not a Prius.