Megasquirt Progress, Main Board complete Options

[yarin]

Tonight I have completed building the main board for my MS II V.3.0 system. Thanks to those that have helped out. Once i'm all finished I will definitely post a complete "How To MegaSquirt a 914" website with pics and step by step. So far i'm still at the desk level. I've got 2.0 injection parts on the way.

I'll be using the following:

stock injectors
GM air temp sensor
stock fuel pump
summit racing manifold referenced fuel pressure regulator
stock injectors (i think 2.0s are on the way)
stock plenum / runners
stock CHT
MS Relay Board
Innovative WB02
High Current ignition driver
Stock dizzy with pertronix (hall sensor)
Stock Bosch Blue Coil
PWM Low impedence injector driver (no resistors)
Stock Cold start Valve (plan so far)
Stock throttle body with some junkyard TPS

Here is a pic of my board, took me a few hours a night every night this week. I took my time, double checked everything. So far so good!

I don't expect to have the system in the car for at least another month. I'm converting from carbs so I want to install steel fuel lines and clean some stuff up.

I'll be sure to post progress in the forums. (IMG:http://www.914world.com/bbs2/html/emoticons/smilie_pokal.gif)

[lapuwali]

IMHO, Dave's experience with solder cup DB connectors is exactly why you should NOT use them in a car. Use DB connectors with crimp-on pins. They're more expensive to buy up front (esp. as you have to buy the right tool to crimp the pins), but they're much more reliable in a high vibration environment.

The other thing I intend to do, and I'd suggest for others, is to mount the board in an oversize box, and run the DB connectors to some other connector that connects to the box side. My actual plan is to put the stock metal box with endplates, but the connectors not tied to them (metal box for EMF protection), and place THAT in a waterproof plastic case. A short cable will connect the DB connectors to waterproof connectors that pass through the plastic case walls. My setup will go in the engine bay.

I'll also rubber mount the metal case inside the plastic case to reduce as much as possible the vibration passed to the board itself.

Mark Henry has had good luck mounting his SDS inside the stock ECU case, and that's also an excellent option. I may still end up doing that myself, since I have a couple of useless 1.7 ECUs. The MS relay board and the MS itself should fit inside the stock ECU case quite nicely.

2.0 injectors will work, just run them at stock D-Jet pressure: 29psi (2 bar). Most injectors now are run at 3 bar (43.5 psi), which is too high for the D-Jet injectors. The main difficultly with 2.0 injectors is they're HUGE for the stock engine, presenting some problems with idle pulsewidths, which are usually down around 2msec. The MS resolution of 0.1msec means you have a minimum step of 5% at such small pulsewidths. Use a manifold pressure referenced fuel pressure regulator (see posts by airsix on how to convert a stock FPR) to help significantly here. You can also sell the 2.0 injectors and find a set of 1.7 injectors instead, which are still plenty large enough for even a modified 2270, yet small enough that idle pulsewidths are a good bit longer, giving you more headroom to get the idle tuned right. Since D-Jet is all analog, it has no "resolution" on pulsewidths, so it can run the injectors right down to their minimum pulsewidths (about 1.7ms) with infinite control.

D-Jet injectors are mostly used because they fit the stock intake setup well. There aren't many hose-barb injectors to choose from. Most need a fuel rail. 1.8 Subaru injectors work (and are smaller than 1.7 D-Jet injectors), as do some L-Jet injectors, and both of those injectors will work at 3 bar, which will give better atomization than 2 bar D-Jet injectors. I intend to use 1.7 D-Jet injectors, because I have several sets on hand, including a NOS set still in original boxes.