Overview Megasquirt is an aftermarket engine management system that can control fuel only (MS) or spark too (MSnS). It is a build it yourself or buy it pre-built system that can utilize most existing factory wiring and sensors, but a VW wiring harness is usually reason alone to rewire. Looking at the big picture it sounds hard, but focusing on each piece of the system one at a time makes it a fairly easy project. This post as well as others can help you with any problems.
Please Everyone chime in with your 2 cents from your own personal experience! This main page is composed of posts and links from several contributors in the VW community.
Use information and megasquirt settings, ve tables, and ignition tables found in this and any post at your own risk!
MegaSquirt FAQ- FIRST Thing to read
Second thing to read, formal introduction, purchasing instructions, pre-assembled kit options, it will get you started
Yahoo Megasquirt Group- Here is a forum dedicated to a anything megasquirt
Yahoo VWMegasquirt Group- A anything VW megasquirt forum/
Official Megasquirt Post in the Forced Induction Forum- Lots of information and a good post to read through check it out!
Link to Megasquirt Ignition post that should eventually have all ignition info for Hall Sensor Ignition Systems!
Anyone can do this project, for real. ’s for all who have got there cars up and running with it If you want your name up here, ill put it up here. Thats how it works.
Engine: 9a 83.5mm JE Pistons, Scat Rods, Stock Head, Turbo
MS ver: MSnS -e
Ignition: Stock distributor wired using MidnightGLI's diagram
Engine: Stock 9a, Stock 9a Head, AEM UEGO Wideband setup
MS ver: MS 2.2
Ignition: Stock CIS-E knock box ignition
Engine: 2.0 16v
MS ver: MS -extra
Ignition: Points with Vacuum advance (On way to MSnS)
92 16V Golf
Engine: 9a, N/A
MS ver: MS 3.0
Engine: 9A with KR head and 'euro' KR cams, 50mm 'euro' manifold, 'euro' everything. 4- brach exhaust header with Techedge 2A0 wideband. Soon to have GSXR1000 itb's
MS: v2.2 board with MS'n'S-Extra 024s9
Ignition : Stock distributor using MidnightGLI's diagram. Soon to be EDIS
Other cool bits: Shift Lights
84 Rabbit GTI
Engine: Stock 1.8 16v (PL)
MS ver: V3.0 With 024s13 code
Ignition: Stock CIS-E Knock Setup.
1993 MKI Cabriolet
Engine: 2.0 16v (9a)
MSnSE ver: V2.2 029q2 code
Ign: Stock distributor wired with LED17 spark out as per OttawaG60
Inputs: LC1 Wideband, GM IAT, GM CLT, Passat 16v auto TB
Outputs: Knock Sensor (KnocksenseMS), PWM Idle control (DIGI II ISV)
1991 Jetta GLI 16V
Engine: 2.0L 16v, i.e. the 9A
MS: v2.2 board with MSnS-Extra 029q2 from Patatron
Ign: MSnS-E using 16v distributor and a digi Bosch ignition module
injectors: Digi2 18.7 lb/hr
1990 Jetta GLI 16V
Engine: 2.0L, TT Street Cams, TT exhaust
MS: V3 board with MSnS-Extra high res code ver 0.08f
Ign: MSnS-E using 16v distributor and MS V3 board ignition module
injectors: 42 lb/hr
Link on msruns.com
Programs or Tools
There are several computer programs needed to interact with the megasquirt unit, and they can be found under the files section in the Yahoo groups forum link above. They are fairly straight forward in use, except the tuning program. The manual is a must read.
List of hardware needed from stock CIS-E to Megasquirt:
-TPS : I recommend a TPS from an automatic passat. The TPS is used for fuel enrichement reactions to throttle inputs. MSII and MSnS -extra code allow for no TPS to be used. Instead the rate of change of the MAP sensor signal is used to calculate fuel enrichements.
-Electronic fuel injectors and harness. See injector choices below.
-DIGI-II fuel injector holders. They will thread right into the 16V manifold
-Adjustable fuel pressure regulator
-High pressure fuel injection hose and fuel injection clamps. (Autozone, Advance)
-Big Bore Intake with cone air filter. You dont have to have the big bore intake, but its easier to find a cone filter to fit that instead of the stock intake pipe.
-Intake air temp sensor. You can plumb this in the manifold behind the throttle body with a tap set, or silicone it into an intake pipe. Intake pipe is recommended.
-Wideband O2 sensor w/ gauge. (recommended) The wideband will seriously help you adjust things to damn near perfect and make it that much more of an enjoyable experience. A perfectly tuned 16V on megasquirt is just awesome!
Sensor choices-Coolant, Air Temp, and TPS:
When following the megamanual in regards to putting the main control unit together and picking the control bias resistor for the sensor inputs... I chose to use the standard 2.2K resistors and use the EasyTherm program to modify the megasquirt control unit for proper sensor interpretation. Basically EasyTherm tells megasquirt how to interpret your choice of sensor.
The stock 16V coolant temp sensor, and a stock Digi II?? (I think) air temp sensor work great. The Bentley manual has graphical read outs for both sensors. The resistance is on one axis, and temperature on another. Using the EasyTherm program, one can easily grab points from the graph and stick them into the program.
The stock automatic 16V passat throttle body, and throttle cable holder (they are different from stock!) bolt right up to a factory 16V manifold and work fine. The automatic already has a TPS on it, so just grab the three pin harness and follow the instructions on how to figure out which wire is which located Here-click sensors and wiring on the leftl. Newer versions of MS such as MSII and MSnS -extra do not require a TPS. They use the MAPdot to figure accel and decel enrichments.
There is only one vacuum port left on the intake manifold after the automatic throttle body install, but you can run up to an auto parts store and pick up a variety pack of vacuum T fittings or make your own vacuum distribution block. Also, there is no idle screw so you have to adjust the resting position of the throttle. When you do this, you have to recalibrate the TPS sensor using MegaTune. (takes like 2 seconds)
Motronic users need to hook up MSnS -extra
If you are running CIS-E, you can use your stock ignition! Simply leave the factory ignition/computers connected and when you are ready to start the car just turn her over
If you hook up MSnS then you don’t have to worry about the tach signal, it comes directly from the distributor.
The (-) lead on the coil typically has a lot of noise in the signal. A much easier and cleaner approach is to grab the green wire coming from the 3 pin distributor harness. Simply attach the tach wire to it. Somebody scared me about that wire being high voltage or potentially being high voltage. Because I didnt want to worry about it I added 3kohm resistor inline with the megasquirt tach lead to this source. Is it necessary? Probably not, but I know the max current that can flow through the 3kohm resistor is very low. Some peoples setups have it, some dont. Mine works fine with it in there.
For the fuel lines I just cut the stock factory lines AFTER the hardware fitting lines so that later on I can install some steel braided lines. Autozones and other places do sell Goodyear brand high pressure fuel line. Thats what I used to connect everything and it is working fine.
The middle fuel line that went to the charcoal canister is some kinda emissions thing. I dont honestly know if you can simply plug it... For now I ran mine up and then back down into a strut tower bar bolt hole. Only thing is, when I had a full tank of fuel I jacked the car up, and when I let it back down... gas came out of it! Not cool!!
Anyone got any ideas on what "should" be done with this thing?
For fuel injectors I am have successfully ran stock 19#/hr DIGI-II fuel injectors. I have adjusted my fuel pressure regulator to 50 PSI, and they work fine at around a max 65% duty cycle.
I also used DIGI-II fuel injector holders, they threaded right into the 16V manifold. The settings for this in MegaTune are Simultaneous, 2 injections per cycle, Required fuel:16.8.
I now have 48# injectors and am going to try to use both injector banks to do it. When UltraMegasquirt comes out I plan on doing sequential injection.
Constants Updated 05/2004
DIGI II Injector constants pictured below
If you have an idle screw or idle issues with my VE map try Ottawa G60’s. Also, you might want to check his constants. He has a megatune msq file available for download from a link in this post:
Enrichments Updated 08/03/2004
The Exhaust gas correctoin settings are set for tuning.
The EGO step % should be 1 and EGO limit 10 or so for normal driving.
The acceleration enrichments are now just about perfect
Warmup settings are pretty good But there is still some hesitation on heavy throttle inputs from idle. Gentle inputs do pretty well.
VE Table Updated 08/03/2004
A Wide Band O2 unit will SIGNIFICANTLY decrease tuning time and is awesome for achieving perfect or desired air/fuel ratios. There is an already calibrated sensor and control unit that can be purchased for about $346. Its the AEM UEGO sensor part number 30-2301. It can be found for this price here http://www.roadraceengineering.com/ems.htm just scroll down a little. There may be better prices out there.
My car idles around 30KPA and most acceleration runs jump immediately to 60+ on the map sensor.
The car also went down to around ~12 KPA when I let off of the throttle at high RPMS and about 20 KPA on decel on lower RPMS
Also, the RPM points may work better if you have one where you reach your Peak HP value. For instance, My car currently reaches peak at about 5800 RPMS on the Dyno, but if I had a point of reference there at 5800 I could possibly tune it for a little more HP.
At WOT you are tunning between two MAP points (90KPA and 100KPA)for each RPM value. The car fluctuates around 95 RPM which makes tuning the WOT points a little more difficult. Keep in mind that it is sometimes necessary to adjust BOTH points to get the desired change.
You can also see where the Peak HP (5800) RPMS is reached. After the peak power is reached the VE has to decrease to maintain the desired air fuel ratio. This value for max power is close to where most stock 2.0’s max out. I am going to say that the factory ignition and a bad knock sensor are keeping the max power at such a low RPM.
The VE Table is really great up to about 4200 RPMS. Its got some holes after that but its still pretty good You can see the developing torque curve much more clearly now. It is more linear compared to before where it was more of a rounded curve. The colors can be confusing as to the actual progression of the percentages, but they are a pretty close representation.
In the future I am going to move the RPM points around to try and tweak my max HP and I will have that tuned better soon. Anyways, this is a great starting point, and the picture is updated below. Just right click on the first link to save the VE table to your computer.
You might also want to check out OttawaG60’s VE table/settings. Again, they are available for download here
How to tune your VE maps
MSTweakComes with some good documentation in PDF Format that you should read before beginning to tune the VE map. There are different settings you need to use for different RPM Ranges. When tuning those ranges you can also setup MSTweak to exclude other RPM ranges from the data by setting the min and max RPM in MSTweak to the specific range you are tuning.
Here is a brief overview, It tells you all this in a lot more detail in the PDF File that comes with MSTweak3000.
Set up your ignition events per second for the different RPM ranges you are tuning. If you want to tune the 1000-4000 range you need to have your stuff in the enrichments set up for that RPM range. Basically, set the Ignition Events per second to about 28-32 and your step% to about 1-2% (2 for more of a rough map). Also, the limit being set to 75% is probably fine, but for tuning puposes you might as well put it at 100%.
For higher RPM ranges 4000-7000 Set your ignition events per step to 64 and your step % to about 3.
Once the map is set correctly or very very close, you probably want to put the limit down to 5-10% and your step to 1%.
Now, thats just megatune enrichment settings.. Be sure to setup mstweak correctly.
VE Range settings: the min RPM equal to megatunes EGO Active Above RPM value... ( Mine is 800 now) and the Max RPM set to 10000 is fine, max Map to 100 is fine for NA.
VE Range Calculation: Should be set to Average, with Outlier Elimination checked. Sigma should be 1.8 or so, and your EGO Crossover Voltage should be .5 for a narrow band, or the target voltage you want from your wideband. (For My calibrated wideband sensor its 3.5340 for about 13.2:1.)
Data Filtering and Fitting: Use 2 step with the second filter% about 1/2 the first one. Also, you should set the first filter from 60-85% Moving higher as your VE table gets closer to what it should be.
Again, most of that tuning information is in the PDF file that comes with mstweak.
I really hope this helps everyone. Megasquirt requires you to read a crapload of information but you don’t have to know it all at once. If you focus on where you are at in the overall project, then it is much more easy stay sane. Order it, assemble it, test it, install it, check over installation, and then try to configure it.
Just some pics of my initial install... I am constantly changing things on this car, but here is how it looked when I first got it done
As you can see, not the best install! I have moved the relay board to the old CIS-E computer location next to the Ign Module and have rewired/cleaned up my whole engine bay.
Modified by GTIMan82 at 2:49 PM 12-27-2006
Modified by GTIMan82 at 7:02 AM 12-28-2006
Modified by GTIMan82 at 7:02 AM 12-28-2006
Modified by GTIMan82 at 11:49 AM 2-4-2007
Modified by GTIMan82 at 3:38 PM 11-21-2007