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** MegaSquirting a V8 - "Basics of How to" ... The A-Z Saga

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But 1st "What is Meagsquirt" ?

Heres an exellent explaination courtesy of Simon R of X-Eng :

"Megasquirt is effectively a DIY fuel injection system.

It was developed as an 'open source' project where lots of people contribute to the hardware and software.

The best bits of design get incorporated into whatever the current version is - and the bits that are problematic do not (by a process of peer review).

The result of this is that it is very solid and reliable - as well as being low cost and easy to install, modify, re-program etc.

The hardware design is freely available - so you could scratch build a MS unit if you wanted to.

Most people however build the hardware from a kit or get some kind individual to build and test it for them.

MS allows you to define and tune your own fuel maps. You can over time make it a perfect fit to your truck rather than a one-size-fits-all ECU or Carb.

Later on in the development, they came up with a way of replacing the distributor by fitting one coil per spark plug (or one between two) and triggering which fires and when electronically.

This allows you to set your own advance and retard curves and tie them accurately to what the engine as a whole is doing.

What you get, or at least can get, is more power, easier starting, smoother running and better economy.

It can be fitted to any vehicle with fuel injection where it just plugs in to the existing injectors.

It can also be used with carbs using what is known as 'throttle body injection' where you disconnect the fuel supply to the carb and fit a big injector which just squirts fuel into the inlet manifold. It just uses the butterfly valve in the carb to throttle the engine as normal.

MS has been fitted to all kinds of petrol engines including chain saws, bikes, lawn mowers - as well as cars and trucks. It is that versatile.

It could potentially be used to run a common rail diesel injection system - don't know if anyone has done it yet though.

Some people have even used it to control LPG, Nitrous or water injection.

To tune it, you load a bit of free software on to your PC and plug it in via serial RS232 or USB via a serial adaptor.

Start with someone else's fuel map for a similar engine then by looking at the mixture via the lambda (oxygen) sensor readout in the software - tweak the settings to be better.

It has an auto-tune function which gradually does this itself over a period of time.

Si R "

And............. before we move on :

There is also Megajolt - this is a similar system that ONLY controls the spark / ie replaces ditribuot

This thread is also possibly of interest :


And finally :lol:, before you move on.....

There are a number of threads now on LR4x4 around Megasquirt.

This one "the A-Z of Megasquirting" you V8.

This is the "Master" thread, read this if you are thinking about Megasquirting your V8, wnat to learn about

whats involved and want it in a simple basic and easy format to understand. READ this thread 1st, if you go to

any of the others at the moment you'll risk frightening yourself, and prob dropping the whole idea of doing it

which would be a bad thing :lol: Once you have read this thread from start to finsih (Be brave :lol:) there are

others to read here on LR4x4.

This thread gives you prob 99.999% of what you need to know and do and how to - and a few bits of info you actaullu don't need :)

Finally, for a Rover V8 MS1 SnE 029v is all you need, there are other Megasquirt Options and Varinats, but you don't need them

at all, thats why may here have MS1 Version 3 029V SNE, and haven';t either upgraded or gone the other routes,

bear this in mind before you choose - MS2 is equally as good as MS1, and in some ways better, but for what we are

doing those extars frankly either are not needed or actually not even used, but some here have chosen MS2 as their

route - for various reasons - and as such to make thing clearer for all I have split MS2 into a seperate thread.

The MS2 thread is here : http://forums.lr4x4.com/index.php?showtopic=39211&st=0


then as if you haven't had enough, there is also an advanced Megasquirt thread.

This was created partly due to the nature of them being advanced Qs and Queries, but again to not melt someones mind

when 1st getting into Megasquirt, 99.999% of what is in there you don't need to know


Megasquirt tends to infect you if you have a desire yo learn understand and erm "Tinker" with things !

The advanced thread is here, : http://forums.lr4x4.com/index.php?showtopic=24961 absolutely definately do NOT read until last :lol:



PS - Finally Finally :lol:

This thread has grown over time, and can make finding items tricky

jamesforee has created this index system -MegaIndex

So, ..........onwards I now go on this Mission :)

Its all that F Fridge blokes fault ................

Megasquirt this megasquirt that,

its the dogs doo dahs days etc etc etc :ph34r:

Eventually he got to me - and I sort of went half way -

I megajolted it - and was impressed,

I thought that would be enough,

I had afterall a now waterproof V8 ..........and the injection side was OKish ...........(oh no it was not). :(

Misfire after misfire has plagued me,

and a mate far better than me on V8s is equally puzzled,

but, at the end of the day when a near 30 year old EFI goes wrong you are in queer street,

and the parts new are frankly £££ frightening..

Even more so when those "Parts" are Jag ones,

the Eales V8 I have had Jag injectors (£128 each) Jag AFM arround £700 sir :ph34r: ) ..........and so it goes on.

I had with mates helk changed tweaked tested and given up......

a call to mark adams sort of sorted it -

in his words the flapper was "Bordeline cr*p when new - at 30 years old just brace yourself".

So, when it works its beautifull, .........water holds no fear,.......

but the misfire arrives when you just do not want it......

OK Mr F Fridge, its 'Megasquirt time' - for the 'Eales'. :)

For those who don't know the "Eales" is an old late 80s Race V8

built by guru engine builder John Eales,

having fully rebuit it I know all is OK - esp after the last EFI Misfire where mate said

"Are you sure you have not hydrauliced it"

and we stripped it fitted a Webber 400 4 Barrelll and all was fine - except it does not like angles side or back or front.

So, I now know the EFI is the issue..............................



The really good news for me is that some work is already done :

the triiger wheel and bracket,

the Coil packets and bracket,

this can be found in the Tech forum here :


This shows the process to get this far

I have now

Fully removed the EFI harness wiring,

and all the megajolt wiring too

so I have a EDIS plug with wires,

2x coil packs with no plugs

and a VR sensor on a bracket with no plug

I will now <drum roll> accept Mt Fridges taunts - and have a go a squirting it - FULLY :o

This post will show exactly how I go about it,

This will include fabrication of both steel bits and Wiring and a how it goes blow by blow. :(

In (advance :hysterical: ) I would like to thank ( in no particular order) :

Mr 'BBC' Ian Gildersleve, Jon White, Fridge, Mr 1664 and Mr Nureophen :lol:

Ok so,

at the mo I have a 4 barrel webber carb,

(this could be similar to a 2x pair of SUs or Stombergs.

Previoulsy it was a EFI Flapper system with JAG AFM and JAG Injectors. It will be coverted to the simplier Hotwire sytem along with abfew trick bits I have aquired, but basically this will help anyone looking to HW and MS a V8

The lambda sensor need a bung or 3 welding in - 3x in Y piece - :


and shove back on,

then remove bonnet snorkel and other bits in the way :

post-22-1182635146_thumb.jpg post-22-1182635242_thumb.jpg

post-22-1182635265_thumb.jpg post-22-1182635295_thumb.jpg

so far the filter housing carn and manifold along with the valley gaskey have been removed

For those V8 Porn merchants out there look at the pic of the valley - towards the front of the engine,

you'll see 2x holes drilled in the front of the block these aid timing chain lubrication,

and are a good Mod on any V8 Build - anyway back to the matter in hand :


Here is the Inlet manifold back on - albiet it a "Porn" version big bore jobbie :)

post-22-1182635580_thumb.jpg post-22-1182635711_thumb.jpg post-22-1182635940_thumb.jpg

Here for the V8 Porn fans are the (left to right) Std RR V8 Trumpet, eales, and then "er Big Thingy Version :) )


Fitted along with Hotwire injectors and rail etc and rocker covers


Fit water pipes which are a nightmare on this as the coil pack bracket then needed modifying and tweaking,

also the Air Box - on the carb V8 the bottom Air cleaner bracket mount to the manifold, to the EFI no chance,

so have modifed welded up brackets so the joining on the back on the head studs

which is a load more work than you think :)

...just a tad of fab later :

post-22-1182636020_thumb.jpg post-22-1182636085_thumb.jpg

Binning the AFM Means a pipe is needed,

here one with a adapter fitted to have a screw in MAF sensor - number later on,

the back of the plemum shows no Air Box and also I have to fir the Bosch 2 wire EAV equiv

or the stepper motor which I have been told the MS can't drive - so more fab. :


Add (in this case Big Bore 4.5 Special Plenum) and the pipe above and it starts to take shape :


With mods to the Bracket for the coild and those and the pipework top Drivers rocker fitted things are filling up :

post-22-1182636613_thumb.jpg post-22-1182636634_thumb.jpg

So, although I have to connect and make whatever to joing the Heater pipes to the pipes on the Driver Rockers,

Bung up the EAV hole on the penum and a few others bit the metal work seems sort of maybe done :)

Next is to build a EFI MS Loom - this will follow shortly - starting tommorow !


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I think MS can drive the Stepper motor. Well, definately MS-II can do.

There were some problems on the forum with the stepper-related idle speed (some high idle after startup which, but when the engine then was shut off and restarted was fine). I think these are thing of the past with the latest code (something with the steps, i.e. the minimum amount of steps to do. Ahh, don´t ask me ..).

The Rover stepper motor looks very much like the GM item as shown on the MS homepage.

If you look at the success stories there is Phillip Lochner with a 4.6 discovery. He is using a stepper. And he experienced those problems. But I think all is well now.

IF MS couldn´t drive a stepper I am running into problems with my rebuild. So don´t prove the above statement wrong !!!

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You're all right - MS as standard will not drive a stepper motor, however the MS-II (a plug-in CPU upgrade for MS-1) will drive a stepper among many other fabulous things.

However, IMHO steppers are more trouble than they're worth - they clog up and stick and are £eeek :blink: to replace. The Bosch valve Nige has is a 2-wire PWM one which MS can drive happily and the wiring is easier too. I have no warmup valve whatsoever on the 109 and so far it's not been a problem.

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As per Mr Fridges comment :

This is the PWM off a Volvo, 2 wire, and tap the number into Ebay and they are plentifull n cheap :)

post-22-1183054497_thumb.jpg post-22-1183054552_thumb.jpg

Comes with a handy bracket, for ease and its also rubber mounted etc, ...and as you can see in the pic the part number

Then the back of the plenum where the stepper motor a la 3.9 not being used leaves a hole,

I guess you could hack the RR one about, but a neater solution I thought would be a 'bung' shoved into it,

It is though a weird thread - enclosed pic of bung and part number and size and pitch - M20 x 1.5 :angry: :

post-22-1183054684_thumb.jpg post-22-1183054786_thumb.jpg

More to follow ..............................

Nige :(

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I use mig wire for Tig'ing steel and stainless, I now the feeling with ally rods - they hurt the wallet and I cant blag freebies :(, its one of those things that cost to build up a decent "library" or rods and then its just topping up whatevers used. The plan is to build an anodising bath next so Ive got to start hunting about for low silicone rods now eeeek

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I use mig wire for Tig'ing steel and stainless

Man I wish I'd thought of that. Even 5kgs of stainless filler hurts. But as you say, its nice to have a 'library'.

Mind you, I'd have to keep stopping with the wire cos the diameter is lower, so the volume per unit length will be, and so I'll run out of length quicker and keep needing to adjust my grip. Its bad enough with some proper tig filler which is thicker, of course, than the mig wire, and I dunno how to feed it through my hand as I go, so I have to stop...

Its expensive buying parts, and its expensive making them!

Hmmm... Al.

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buy a reel of fat wire, 1.6 or 2.4 (I havent got enough horsepower at the lab to need much bigger than that until the autum). cut what you need into 1 metre lengths, straighten them with a pair of pliers and 3 fingers and away you go :) a 15kg reel of Mig wire goes a looooooong way on a tig.

have a look for a Tigpen if you're having "feeding" probs

sorry for the hijack BTW Nige :ph34r:

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Righty Ho then campers :)

With a TIGged up AFM replacement ........with the MAT (Manifold Air Temp) sensor in it :


...And I hasten to add TIGged up by a grown up ....- not me :lol: - ta Mark and Jez

Having got this it was on to the wiring :unsure: now, a couple of points :

I am absolutely useless at electrics, so,

1. If I can do this so can you..................

2. I am documenting exactly what I have done......................

It may well be that in Guru Wiring Circles what I have done is either wrong or poor standards -

but I would say that I have done it this way cos its about the only way that makes sense to me as a Electrical idiot

and as such other may get confidence from the way I have done it....or maybe not :lol:

Ok here we go :

1st HUGE F Thanks to 'Mr Fridge' for a MS wiring diagram :


Couple of things :

1st - this is a digram for colours relating to a RR 'Flapper' colour wire system,


2nd - this now has a 2 wire Bosch EAV Equiv rather than the RR stepper, so the wires have changed :) from 4 to 2 orange and black as earth

3rd - a Black "DOT" on the paper means I have fitted at least the base end of the wire :)

I am making a complete loom up to run MS so here is what I have done :

1. I have learnt studied and looked at this wiring diagram till I can almost draw it by memory.

This is important, ..............

I think I needed to understand why which wires go where as best I can.

If you are think "NAH" forget that look learn and study it so it makes sense

..........and you an almost draw it blindfold - it helps belive me :)

2. I have ordered initally (I am building a '1st loom' ....then maybe a 'finished' better Raychem one from one colour :o so one the 1st one you can see the exact colour wires and tracers - more later

3. I expect this to take some time.........and so should you .......... if it is to be .........

....1st neat and 2nd relaible

Having 'studied the hell' out of the above wiring diag I ordered the wiring,

I had different thickness dependant and the usage and for this I thank Ian (BBC) for his input.

On some sensor wires I could not get TWC (Thin Wall Cable ) with the correct colours so went up in size so I could get the right codes


As such I ended up with the following order with VWP.

MegaSquirt Wiring

PIN(S) Colour Wire What Wire Size Goes to

19 Green 0.5 To Throttle Pot

37 Blue & Pink 0.5 Fuel Pump Relay

32 Red & Green 0.5 PWM

30 Pink 0.5 EDIS Pin 3

29 Green & White 0.5 PWM

26 Yellow 0.5 To Throttle Pot

24 Slate & Orange 0.5 EDIS Pin 1 (slate yellow ?) 23 Blue 0.5 Lambda

22 Red 0.5 To Throttle Pot

21 Black & Slate 0.5 CTS

20 Red & Black 0.5 ATS

18 Black 1 Earth

Brown & Black 1 EDIS 12

Brown & Green 1 EDIS 11

Brown & Orange *2 time 1 EDIS 9

Brown & White 1 EDIS 8

35 Slate & Red 1 5 6 7 8 Injectors

34 Slate & Red 1 5 6 7 8 Injectors

33 Slate & Green 1 1 2 3 4 Injectors

32 Slate & Green 1 1 2 3 4 Injectors

Brown & Orange 2 Main Relay to All Injectors 28 Blue & Yellow 2 Main Relay & Edis Pin 6 White & Purple 2 Fuel Pump Coil Feed Lambda

BIG Brown 3 Relays Main and Fuel

If you look at the above Diagram from Mr Fridge and then the above you'll see the wire sizes and colours I ordered to make up the loom.


I now have a HUGE delivery from VWP, .............

and this is exactly what I did........

...................................................so far :lol:.......................

I decided to build the loom from the engine into the 90,

so the 1st jobbie was to work out eaxtly which wires I neded from the engine into the 90.

Then once I have worked out which wires are in the engine

I will switch my attention into the cab area and work out which wires so far from the engine into the cab area

go to either the ECU Fuse box or EDIS unit realy earth etc etc .

Once I have done that I will add in the extra electrics that are cab area based eg

Fuel Pump Lambda sensor Fuses relays and earths.


To start with I worked on electrics in the engine area.

I split this down to start on the Pass side ie 1 3 5 7 vs 2 4 6 8

on 1 3 5 7 I have the injectors (A) on the diagram, ATS (D) CTS © TPS (E)

Panic already set in, so many wires :lol: ....so I decided to start with the 'Bank injectors' :lol:

I simply started at Injector 1, shoved 2 wires through the bulkhead Grey and Green and the feed Bown and Yellow,

I taped up BOTH ends and shoved a lable on to identify what they were,

I then did this with 1 3 5 7 and then CTS ATS TPS and then as they grew I kept zippy tieing them up

and repalceing the zippy ties each time they grew,

this way I have a harness taking shape the zippy ties are mainly either at junction points

or there to hold the loom together,

It is frightening after a short while what wires you have and the thickness of the loom.

For the injectors I ran 4x wires for the injectors and the feed as well, as these will be "Joined" close to the ECU.

For the ATS and MAT the "Earths" run right back poss to the battery cahhsis etc so another number of wires.

Again these are linked and marked with what thety are into the cab, each "Unit" into the cab is not only marked

but wound into a coil and zippy tied.

This then gave me the '1st bank', then I moved to the drivers bank.

This meant then same but for

2 4 6 8 AND Coil Pack 1 (3 wires 1 2 and feed) and coil 2 ..........so 6 wires in total

This then meant a harness from the bulkhead to each bank,

zippy tied as you go adding and replacing - but all wires maked, after a days work looks something like this :

This shows :

1 3 5 7 ATS CTS EAV (2 wire Bosch unit) and the VR Sensor (grey sheilded wire)


The the other side

2 4 6 8 Coil Pack 1 and Coil Pack 2


Zippy ties out of my ears and then back to the bulkhead


This is towards the end of the day,

but I keep re zippying (cut off the old add the new) as it grows,

this shows virtually every thing for the engine bay.

Fridge and BBC both suggested that ALL earths should be brought into the cab for a good solid earth area(s) ...............

................and this does NOT Include using the V8 Engine Block :)


Next is inside the cab area,

although everything is nmarked I will next have to move the Edis ECU FP Earths Relays etc etc so as to make sense,

at the mo it is slighly frightening as thus :


It is very much '1 stage' at a time,

and also you will note the engine bay has LOTS of slack / spare cable for the 'connectors'.

My plan also is the add... say 'yellow' heat shrink

pre the rubber boot with the 'item description' written on it..............

................ie 1 2 3 4 5 6 7 8 MAF ATS CTS etc etc ...............

.......then add clear heatshrink over the top to keep safe........

Lots to do but.................................

I do feel I am getting somewhere now :rolleyes:

More Next week, ..............

frankly I have had about as much 'Electric Joy' as I can take this weekend :lol:



13th Match 2009 - clearer version of the wiring diagram sir :) ?


Come back here soon :)


Edited by Hybrid_From_Hell
<cough> and who forgot the White for Switched ignition !!!!
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Fridge and BBC both suggested that ALL earths should be brought into the cab for a good solid earth area(s) ...............

................and this does NOT Include using the V8 Engine Block :)

One of the major milestones in curing my MS re-setting problems was to seperate the coil earths and normal earths, both hated being anywhere near the engine block, the resets almost stopped when I earthed the coil to chassis and the normal ms earths to in the cab (which is linked straight back to the battery, I was informed by Phil Ring wood [MSnS god] that the battery is the best suppressor on the vehicle).

The resets completely stopped when the spark plugs were gapped exactly the same with new leads.

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Its coming along nicely Nige ................ like i told you ....... electrics is easy ............. you only get smoke if you get it wrong......... and mirrors are usually hung on walls. ;)

One of the major milestones in curing my MS re-setting problems was to seperate the coil earths and normal earths, both hated being anywhere near the engine block, the resets almost stopped when I earthed the coil to chassis and the normal ms earths to in the cab (which is linked straight back to the battery, I was informed by Phil Ring wood [MSnS god] that the battery is the best suppressor on the vehicle).

The resets completely stopped when the spark plugs were gapped exactly the same with new leads.

Yes, the battery acts like like a f/off big capacitor for removing DC line ripple .................. but also a battery has not only capacitance, but also inductance and pure resistance, therefor it has C,L, & R so will therefore represent impedance (in the true sense of the meaning) to any AC signal.

Engine blocks are notoriously bad for producing 'noisy ' earths ............ signal grounds should avoid this route if at all possible, and be grounded as close as possible to the battery. LR's are also quite bad at producing earth loops ( an earth loop is where the the resistance between the main common earth and other earths varies considerably) mainly due to the method of construction and the usage of dissimilar metals ............. earth loops can give rise to all sorts of unusual and difficult to diagnose problems.



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Tony, as a guide, how much of the spiral wrap will do how much cable?

Lewis :)

Not easy to estimate, since it depends how closely you wrap it & how much you are expanding its diamter.

In most cases though i would expect 2:1 on length used.

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