Setting up MS2 V3 for a 4age 20v using MS2 Extra code.Patrick Neal4th Jan, 2010

This is a guide to setting up MS2 V3 for the 4age 20v using OEM sensors and ignition with no modification.My personal aim was to be able to swap the MS and OEM ECU easily in case problems occurred. Although I found building and setting up MS quite pleasurable and fairly straightforward, I would not recommend this type of thing if you want a straightforward joint part A to part B, add part C, buy the T shirt, apply the stickers and go race. If you are a cheque book hobbyist, Megasquirt probably isn’t your cup of tea.I have to say that I am not an electronics expert. Quite the contrary, I am no more than a low level hobbyist. Take this info as a guide only, I can take no responsibility for the problems you get yourself into or if you use my MSQ or fuel maps file without modification or tuning.

This information has been gathered from many sources with the Megasquirt for dummies thread on club4ag.com being the most informative. The Megasquirt forums have also been invaluable, although there is just too much info and 99% of it is not relevant. What I found impressive was the quick response to questions. Board designers or MS firmware writers generally answered the questions I placed, these guys are very helpful as is the staff at DIY Autotune.

Manuals required or worth reading V3Assemble.htm Assembly instructions for the V3 board MS2-Extra_Ignition.htm Ignition hardware set-up when using the extra code MS2-Extra_Nippon.htm Instructions for using the Nippon Denso distributor MS2-Extra_Conversion.htm Instructions to install MS2 Extra code and general Megatune set-up. Zeal board or similar VR conditioner board construction and install. Toyota Vast ignition The 20v doesn’t use Vast, but is similar-ish MS2-Extra tuning guide.mht. These two documents are almost the same, but not quite so read both. Tuning Your Megasquirt-II (or MicroSquirt).mht

Some of the above info is not relevant to this install, but is worthwhile taking a look, you might fancy trying COP, (coil on plug), wasted spark, launch control or something else at a later stage.

Build the V3 main board as per instructions except: Do not do step 22 Do not do step 50 you can build this part if you wish, but the 20v will not require it, so it will be disabled in favour

of the VR circuit in step 51. Do step 51 Do the VR sensor jumpers on step 52: VROUT – TSEL (not VROUTINV). Replace the resistors R4 and R7 with 2K2 resistors. These are not included in the kit. Step 64, do not install Q4. Check the instructions for the PWM idle valve just below where it will explain how to fit

a TIP120, 121 or 122 transistor for your 3 wire idle valve. Do step 65, although do not jumper it exactly way it shows in this manual. Look at the MS2-Extra ignition manual

for using the D14 LED for Spark A output, although you will need a 5V pull up resistor as indicated on page 16 of the V3 main board manual.

Do not do step 69, the 20v has high impedance injectors. The space that these components take up on the heat sink can now be used by other components such as PWM FIdle and the VVT output transistors.

Second VR conditionerYou will need to build a second VR conditioner, you can build it in the Proto area, although I decided to build a 3-wire idle valve circuit there and use a separate Zeal board for the VR. Modification to the Zeal board VR circuit as posted by Ken Culver (Zeal board designer):Put a ceramic .01uF cap across G+ to ground and also ground pin 14 of the lm1815 chip.

This small modification cleans up some of the noise issues people have had with using Nippon-Denso Dizzies.To date I have not had any issues with the ignition, it just ran.

Idle controlThe 20v uses a three wire PWM idle valve.Here is the 3-wire circuit.

I built this circuit in the proto area. There is now not much space for anything else. You could build a separate 3 wire board and have it in the case, or outside the case as indicated by the diagram. Or don’t bother with the 3-wire circuit and follow the Megamanual’s suggestion and simply put a resistor onto one of the 3 terminals of the 3-wire valve. I am unsure how well the simplistic single resistor method works – probably just fine.I have found closed loop PWM idle control is a bit erratic when the maps are not flat in the idle area. You could of course not bother with a fast idle. I set my normal idle mechanically @ 800rpm instead of relying on the idle valve, when you are setting up maps the last thing you want to do is struggle with the idle valve settings. Under the velocity stacks you will find 4 air-bleed screws to adjust the idle speed. From the factory they are set low and I doubt it’ll idle without adjusting these. Make sure they are kept synchronised to avoid an unbalanced mixture at idle.

VVT OutputHere is the output circuit required for the VVT, although you can (and I did) replace the 2N2222 with a TIP122 transistor and do away with the relay. The TIP122 will fit on the heat sinkI connected this circuit to the IAC2 pin on the CPU under the V3 board and Spare 1 on the DB35.I set it up so the VVT comes on at 3500rpm with 70% TPS.

If you do decided to use the Zeal board, it has an output circuit just like the one above, but it will not drive the VVT directly, you will have to use a relay for this.

Here is the link to the MS2 output section of the manual http://www.msextra.com/ms2extra/MS2-Extra_Hardware.htm#outputs

Setting up in Megatune Firstly install the MS2-Extra firmware. The 3x firmware (currently in Beta testing) will enable better fuel control of the ITBs (Independent throttle bodies). In saying that, the 2x code I am using seems OK. I believe Megatune won’t work with the 3x code, you’ll have to use Tunerstudio.Make sure you follow the instructions for installing this as I found an icon for downloading the firmware onto the MS2 Ecu and it didn’t seem to work. I found this frustrating starting a bit of a Spanish inquisition of checking all of my work. As it turned out the icon doesn’t work, you have to use a boot loader program. If I had only read the instructions! Follow the instructions in the MS2-Extra conversion manual. Set up the ignition settings as per the Nippon Cas instructions except spark out should be Normal, not inverted, this

is very important if using the ignitor! Dwell is controlled by the ignitor. I originally set the dwell as per the MS2_Extra Ignition manual and had no

issues. But as the ignitor controls dwell, I later changed to fixed dwell with a duty cycle of 10%. Any higher and it got hot. My method is hardly scientific, but I have had no issues with misfires and the ignitor is barely warm.

Idle control is PWM. Closed loop will probably not work well until your maps (VE and Advance) are sorted and fairly flat around the idle areas.

VVT on the programmable outputs, I set it up thus: RPM > 3500rpm, TPS > 70%. I found the standard 4000rpm kick in gave a bit of a dead spot between 3000 – 4000rpm (factory ECU), you could feel the change in performance. Setting at 3500, the kick in is hard to detect which to me, means it is probably about right, although my car only weighs 550kg. I connected the check engine light to the same output to monitor what it is doing.

Thermistor settings will need changing in Megatune to calibrate to the Toyota sensors. Cooling system sensor32 deg F = 6.02 Kohm77 deg F = 2.080 Kohm212 deg F = 230 ohmIntake Temperature sensor4 deg F 15 Kohm32 deg F 5.5 Kohm68 deg F 2.5 kohm140 deg F .55 Kohm

TestingI used the Jimstim because it could simulate the Nippon Denso dizzy’s signal.Unfortunately the Jimstim would not trigger the second VR circuit. Jean, the designer recommended using a 0.01uf cap in series with the VR2 jumper wire to turn the square wave the stim’s second trigger output produced into a sort of crossover signal. I have to assume this’ll work, but I didn’t bother trying. The car was running by this time.

WiringI built an adapter using a plug from an old ECU, I think from a Honda. Don’t bother trying to remove the plug with a solder sucker, just cut the pins close to the board. Make sure you use heat shrink on all of the wire joins. The plug was housed in a sheet metal box. The box is large enough to store another circuit or a relay if so required. It is velcro’d onto the stock ECU at present just in case MS fails. I doubt it ever will, but it takes up stuff-all space.

The only thing I think worth mentioning of great importance is the wiring from the G1 and NE sensors to the Megasquirt is best to be shielded. Use a light 2-core cable with shielding. The shield becomes the common negative wire from both sensors.Below is the pin outs for the blacktop. Silver top pin outs are different and available off the net. I have read at least one other install that said that Toyota wires up their TPS reverse polarity to other manufacturers, I have not found this the case, it wires up standard.Linking it all up is fairly straightforward. Silver top has an AFM, get rid of it, the wires can be utilised for the air temp sensor. Leave +B, this is for a non-switched supply to stock ECU. RSO and RSC are the idle valve wires, if you get them mixed up, you can reverse them in Megatune. Don’t bother with CF and ELS2 unless you want a second cooling fan. The main fan does not use the ECU. FC is your fuel pump relay Pair 2 injectors together as MS only has 2 injector outputs IGF can be left open; IGT goes to your ignition output. Use the G1 sensor to the zeal board, and Ne signal to the MS, leave G2 open. G- is the common ground wire for all dizzy sensors, use the shield wire for this. VC is wired to the 5v TPS feed on MS. Definitely connect up an inline fuel filter in the MAP hose as a vacuum damper. As an extra precaution I also put a

restrictor with a 2mm hole into the hose as outlined in one of the tuning guides.

Here is a shot in the foot-well of my car. It isn’t the final resting spot for the MS, it is just assesable.You can see the MS in the foreground and the stock ECU just in behind. The adapter box is velcro’d onto the stock ECU, I can switch back in the event of a problem. You can plainly see the fuel filter in the MAP line positioned close to the MS. The random white wire goes to the Wideband controller above the foot-well.

Patrick Neal