Megasquirt - The FAQ

I thought i'd try and collect some of my generally incoherent ramblings all in one place. It might help someone, you never know Most of this is dealing with installing MS to a 16v mk2 Golf, but i'll add anything I think of along the way as well.


Firstly, if you're considering installing Megasquirt in your car/boat/lawnmower/jetski (yes, it has been done) your first port of call should be the MegaManual. Virtually everthing you need to know is in it, as well as a whole load of stuff you don't. Don't worry if it looks intimidating at first, everyone gets that. Skim through it and try to pick up what you think are the important points, then read it again later and see what you missed. Megasquirt also has it's own forum, this is the place to keep up to date with the most recent developments.

A major development to MS has taken place in the form of MegaSquirt'n'Spark-Extra. This is a firmware upgrade to Megasquirt that expands the feature set to include spark control as well as a whole host of other funky stuff. Most of the features of -Extra are listed on the website, however development continues to trundle along far faster than the documentation. -Extra can control several different spark implementations, one of which is the dizzy/TCI module used in our VW's.

Parts required (for K-Jet 16v)
Megasquirt ECU with stimulator, optional relay board
O2 sensor
Air temp and coolant temp sensors
Throttle position sensor
Air filter
Fuel rail
Injectors
Fuel lines
Fuel pressure regulator
Wiring parts
A laptop with serial port

Megasquirt ECU


Click on all the pics for a bigger one

The Megasquirt ECU comes as a kit you have to assemble yourself. The original way to purchase the MS (and still one of the fastest) is to order the Partial kit from Bruce and Al and the components from DigiKey using the bill of materials provided. There are now many other suppliers, some who also sell ready made kits. Bill Shurvinton keeps a decent amount of stock in the UK.

The stimulator board allows you to power up and test the MS off the car, and is invaluable. Another option is the Relay Board, this brings together all of the engine bay wiring back to a single point for a potentially easier install. I didn't use a relay board because i'm a masochist and like wiring, you may not

Oxygen Sensor



There are a couple of options for the O2 sensor, the main one is whether to have a narrowband or wideband. For a normally aspirated engine narrowband sensors are perfectly adequate, either a new 'generic' sensor from somewhere like Just Lambda, or a second hand one robbed from the scrappy (from virtually all 90 onwards cars). Make sure the sensor is a zirconia type, and preferably heated (three or four wire) to allow you more choice in where to mount it. A heated narrowband sensor can go pretty much anywhere betwwen the head and the first silencer, try to keep the sensor close to vertical to stop it from collecting condensation inside. You will need to get a sensor bung welded in, or an M18x 1.5 full nut will suffice. Find a Powerflow dealer/decent exhaust place to do it for you.

Wideband sensors are a big help when it comes to tuning the VE map, and are recommended for forced induction engines where the risk of damage from an incorrect mixture is that much higher. Wideband sensors need to be driven by a separate controller,and this puts the price up compared to a narrowband. Techedge, Zeitronix, and Innovate all supply affordable WBO2 kits.

Temperature Sensors
Intake temperature sensors can be found in the scrapyard, MS can be calibrated for any NTC sensor so you needn't be too fussy about what it comes off. Try to find one with an exposed element, it will respond faster to changes in temperature (this is particularly important for forced induction). For a forced indutcion engine it needs to be mounted so it reads the temp of the inlet charge going into the engine. NA engines are less fussy, anywhere in the inlet tract is OK. I've mounted mine in the hole where the ISV used to feed back into the inlet, using the rubber elbow off the ISV.



Coolant temp sensors are just as easy. If you are ditching the ISV or using MS to control spark as well as fuel, then you will have a couple of spare coolant sensors you can use for MS. If not, you could see if you can find a sensor to fit in place of the thermotime switch. Don't try and share a sensor with something else, it very rarely works how you'd like.

If converting from digifant you can use the blue temp sensor.

Throttle Position Sensor
MS uses the TPS to trigger acceleration enrichment, or can use it as load input in Alpha-n mode. The TPS has to be a linear resistance type, the idle/WOT switches on older VAG cars aren't sufficient. You can either figure out how to attach a suitable throttle potentiometer to your throttle body, or just find a TB that already has one. Said TB's include Passat 16v automatics, some Audi 5 cylinders (NM and 7A engines, probably others) and some G60's.

.

RS sell a pot to fit 'D' shaped throttle shafts if you can find a way to attach it.

Air Filter
Ditching the metering head and all that gubbins leaves you without an air filter. The chavs out there will be happy to know you can fit a cone filter, if you're using the original inlet pipe you need a filter with a rubber neck, 70mm inside diameter. Pipercross sell a cheap universal filter, or you can get measuring other cars to see what will fit (probably a digi filter will fit). For a more OEM look the digifant airbox can probably be adapted to connect up to the 16v.



The cone filter needs supporting, it's easy enough to make a bracket to bolt to the strut tower.

Wiring
The more colours the better. The cheapest way to make up the wiring loom would be to just buy a 100m drum of black cable and make it all out of that, but i wouldn't want to have to troubleshoot it. Maplins sell coloured equipment wire in 10m lengths. Solder and heatshrink is the best way to join wires, try and keep removable connections to a minimum.
If you aren't using the relay board then you'll also need a couple of 12v relays and fuseholders, I got a small SAAB fusebox from the scrappy.



Connectors for the injectors and sensors can all be got from the scrapyard (make sure you cut them off with a reasonable amount of cable to solder on to), or if you want new ones try Vehicle Wiring Products. The majority of injectors (except some jap ones) use junior power timer connectors, as do most Bosch sensors.

Fuel System

Do not cut corners on the fuel system! High pressure fuel and engine bays don't play well together. A couple of quid spent on proper fittings is cheaper than a burnt car.

Fuel Rail
The choice of rail is dependant on your intake system.

K-Jet 16v manifold - the manifold is in the way, basically. You need a rail with long 'fingers' to reach down between the runners to the injectors. Sadly there aren't any other vehicles you can get one from, so you either have to fabricate one, or buy one from the US (Ross, BBM, Eurospeed). Eurospeed do sell a rail that fits under the manifold, but rumour has it that it tends to leak. Ross also sell extrusion to fabricate your own rail.



ABF - you can use the ABF inlet manifold and it's fuel rail/injectors/fuel pressure reg. However, the injectors are an odd stumpy type that are fairly uncommon, meaning upgrading them if you need more fuel could be tricky. Apparently there are higher flowing injectors from a Primera that will fit. If you only need a little more fuel, you could always raise the fuel pressure, but there is a limit as to how much you can do this. Using the ABF manifold means everything I wrote up there about the throttle pot becomes rubbish, as the ABF uses a different TB (but I think it has a TPS anyway?)

ITBs - with the manifold out of the way mounting the fuel rail becomes much more flexible. A 20VT rail can be adapted to fit as it has the same bore spacing as the 16v. Jenvey also sell suitable rails for good money, ask Bill about them.

Digi 8v - the existing setup will work as is. Upgrading the injectors is easier as they are the much more common Bosch style.

Injectors
You need EFI fuel injectors, the CIS ones are basically nothing more than a spray head. First you need to determine what size injectors you want, either by calculating the flow rate, or by sourcing them from an engine making similar power to yours (with the same no of injectors). Don't go too large as it will make your idle tuning more difficult. MS can use either high or low impedance injectors. When buying injectors make sure you get the right flow rate, don't rely on injector colour. There are hundreds of different spec injectors, and only so many colours, go figure. EBay is a good source of cheap injectors, there's always a few sets of Cossie injectors for next to no money.



To fit the injectors in the K-Jet manifold you need to remove the injector seats from the manifold (13mm allen key) and replace them with digifant injector seats (VW part no. 037 133 555 A)



Fuel Pressure Regulator
This is where a Power Boost Valve actually has a use All it is is an adjustable fuel pressure reg, perfect for this application. The standard Bosch FPR off digi cars is also fine, but a little harder to mount than the remote mounted ones unless you use an OEM rail or the Ross/BBM ones with the adapter. Also bear in mind that most injectors are rated at 3 bar, so if you run at a different pressure to this you will have to take it into account.

Fuel Lines
Braided lines are bling, but expensive. Plain fuel hose only costs a couple of quid a metre. You decide. Make sure the hose is proper high pressure fuel injection hose, hose meant for carbs isn't useable.
The fittings on the end of the hard lines from the fuel pump are M12x1.5 on a K-Jet car. The black line is the supply, and blue is the return line. On digi cars there are no fittings on the hard lines, the flexible line pushes on and is fixed with a hose clamp (NOT just a normal jubilee clip). The fittings for the rail/FPR obviously depend on what you use.
The best option is to get the lines made up for you with properly crimped fittings. Think Auto or FSE can do this for you, or look in your yellow pages for a local supplier.



Putting it all together

First thing to do is take off all the stuff you don't need:
Injectors and fuel lines
Cold start valve and it's fuel line and wiring (either leave the thermotime switch in or find a suitable plug for the hole)
WUR and fuel lines
Airbox with metering head/diaphragm switch etc



If you're using MS'n'S-Extra to control spark as well, then you can whip out the ignition ECU and it's complete wiring loom (you'll need the hall sensor connector off it later).

ISV - you can either a) keep it, b) lose it, or c) control it with MS'n'S-Extra.
The ISV is a separate system to the fuel/ignition in a 16v, so should be quite happy running alongside MS. The more adventurous amongst you might like to try controlling it with MS (it'll tidy up the wiring a bit, free up a coolant sensor if you need one, and gives you more flexible control over your hot/cold idle, which may be handy). I'm running without the ISV only because I intend to move to ITB's and the ISV isn't really an option then, and getting a decent idle is giving me all sorts of grief.

Removing the CSV leaves a hole that needs blanking off, or you could leave it in but disconnected.

The crankcase breather needs redirecting now the airbox has gone, either some form of catch can/filter, or redirecting back into the intake.

Vacuum - The Megasquirt ECU and the fuel pressure regulator both need manifold vacuum. The line that used to go to the diaphragm switch can be redirected to the FPR or ECU. If you've removed the VW ignition ECU that had a vacuum line that can also be redirected or blocked off.

Mounting the ECU - put it somewhere you can get to easily, you will need to access quite a bit at first. Mine is under the passenger seat, others have used the glovebox or centre console. For god's sake don't stuff it up behind the dash, it'll drive you bonkers.



Tip of the day - leave wrapping the looms right to the end, once it's all up and working. Unwrapping the same bit two or three times gets annoying

Tach feed for MS - if you're running fuel only take the rpm feed for the ECU straight off the centre pin of the hall sender into pin 24 of the ECU. The signal is much cleaner than coil negative and eliminates the risk of processor resets. If you want to use coil neg, or do have tach signal issues, have a search in the Megamanual for the 'Dave cap'.



Spark


pic courtesy of MidnightGLI on VWVortex

This pic says it all really, wiring up spark control is just that easy. The one change I have made is to jumper JP1-8 straight to pin 24, instead of via X12/pin 27 (to free up pin 27 for another output. You don't need +5v output for anything, and if you did, it's already on pin 26 and 24).

All the documentation refers to Bosch ignition modules, but the Telefunken TCI module in all the european VW's is exactly the same. You need to get the connector for the ignition module off a mk2 driver or other carbed VW (i found one on a passat), the 16v one only has 4 wires connected you need 6. The connector for the hall sender can be cut off the old ignition loom, or from another in the scrappy if you want the old loom intact.

You also need to mod the stimulator if you follow the above diagram, otherwise you'll burn out T1 (on the stim) sooner or later. What you have to do is cut the track on the underside of the stim between R9 and pin 24, and replace it with a jumper from R9 to pin 25 instead.


It's the lower cut and short green wire, the others are mods to simulate WBO2 instead of narrowband.

Setting the distributor and spark settings:
1) Rotate the engine to TDC
2) Power up MS (once you have set it to MS'n'S mode)
3) Rotate the distributor so that the middle LED on the ECU is on. Now rotate it anti-clockwise until the LED just goes off (sets cranking position).
4) Fix the distributor in that position.
5) Set the 'Trigger Angle' in MS to 70 degrees, and the 'Fixed Angle' to 10 degrees
6) Start the engine, and check the timing
7) Adjust the 'trigger angle' until the timing light reads 10 degrees. Don't move the distributor.
8) Set the 'fixed angle' back to -10




Some Megatune screenshots (MT 2.25 build 447):





My recent(ish) setup files:

MSQ - For MS'n'S-Extra version 021v
VE Table VEX format
Spark Map

Feel free to ask questions/point out the bits that are horribly wrong. I know i've forgotten some things, my brain is aching after typing all that



Useful Links

The Megamanual (Megasquirt FAQ)
MSEFI Forums
MegaSquirt'n'Spark-Extra
Some VWVortex Posts:
Official Megasquirt Post
Megasquirt from CIS-E
Megasquirt'n'Spark
Yahoo Groups (these aren't used much these days, post on msefi instead):
Megasquirt
Megasquirt UK - UK list
MegaVAG - Unfortunately named VW/Audi specific MS discussion
Megasquirtnspark

EDIT: added tach input info, spark stuff, links

Edited by: Trev16v

 

Top Score!

 

Nice one!

 

i'll make this a sticky/FAQ once any questions posted have been answered, if that's alright with you martyn?

 

No worries, i've already thought of a couple of things I missed

 

That's great, nice one Martyn

 

Wow, what an excellent effort

 

Spark


pic courtesy of MidnightGLI on VWVortex

This pic says it all really, wiring up spark control is just that easy. The one change I have made is to jumper JP1-8 straight to pin 24, instead of via X12/pin 27 (to free up pin 27 for another output. You don't need +5v output for anything, and if you did, it's already on pin 26 and 24).

All the documentation refers to Bosch ignition modules, but the Telefunken TCI module in all the european VW's is exactly the same. You need to get the connector for the ignition module off a mk2 driver or other carbed VW (i found one on a passat), the 16v one only has 4 wires connected you need 6. The connector for the hall sender can be cut off the old ignition loom, or from another in the scrappy if you want the old loom intact.

You also need to mod the stimulator if you follow the above diagram, otherwise you'll burn out T1 (on the stim) sooner or later. What you have to do is cut the track on the underside of the stim between R9 and pin 24, and replace it with a jumper from R9 to pin 25 instead.


It's the lower cut and short green wire, the others are mods to simulate WBO2 instead of narrowband.

Setting the distributor and spark settings:
1) Rotate the engine to TDC
2) Power up MS (once you have set it to MS'n'S mode)
3) Rotate the distributor so that the middle LED on the ECU is on. Now rotate it anti-clockwise until the LED just goes off (sets cranking position).
4) Fix the distributor in that position.
5) Set the 'Trigger Angle' in MS to 50 degrees, and the 'Fixed Angle' to 10 degrees
6) Start the engine, and check the timing
7) Adjust the 'trigger angle' until the timing light reads 10 degrees. Don't move the distributor.
8) Set the 'fixed angle' back to -10




Some Megatune screenshots (MT 2.25 build 447):





Recent setup files:

MSQ - For MS'n'S-Extra rev 021v
VE Table VEX format
Spark Map

 

nice work almost makes me want to buy one again now

 

Nice 1! That has made it alot easier to understand now!
Can you cut the meterhead unions off the k-jet fuel lines and then slide fuel injection hose over with fuel clamp? Also ive read that if running itbs,you need a fuel rail without a deadend,il be using a 20v 1 if i can source 1 so will it work with itbs?. Is it best to use fse boost valve instead of 20v pressure reg?

Thanks again!!!!

 

One of the best posts I have read in a long time. Very useful.

 

I should have some specifics to add to this about the ABF manifold set up soon. And possible sensor sharing .

Good work Martyn_16v

 

Wow, excellent writeup, understandable even for me. (and I think K-jet is pretty weird and probably involves some kind of magic)


I guess it would be pretty similar if I wanted to go MS&S with my 3A-block+JJ-head NA 2.0 8v?


/Mats

 

Do you mean cut the fittings off the hard lines back to the fuel pump? You could, but the digi lines have a metal tube inserted in the ends of the lines to stop them collapsing under the hose clamp, so you likely need to do the same.

 

Think he means the banjo (?) connectors on the end of the engine bay fuel lines that connect to the metering head. Cut off the banjo's leaving the couple of inch's of metal tube at the end of these lines. Then fitting fuel pipe over these ends and clamping.

I thought about doing this as a temp bodge.

I now intend to just get adaptors for the fixings on the solid lines.

 

Excellent write up.

This is something I'd really like to get my teeth into sometime. Perhaps a nice project for next year?? (It's another good excuse to not do any DIY around my house anyway)
Edited by: hayesey

 

Ah OK. If you're going to cut up those lines you may as well do it at the other end, the M12 fittings that attach to the hard lines are barbed, so you should be able to cut them out and fit them to a new length of flexible hose.

 

top banana

 

will it run 8 injectors?

 

excellent thread.