Fuel, Ignition, Monitoring

Bye bye Bosch D-Jetronic and CDI ignition :)

Hello MegaSquirtII EFI and Distributorless Ford EDIS ignition.

Above is a shot of *some* of the wiring and components going into this. I bought the MS pre-built, but then updated it with a MSII plug-in chip, and some re-soldering of a couple components on the MS board.

Here is a list of what's going into the fuel, ignition, and monitoring devices:

-MegaSquirt II MAP-based EFI controller
-Relay and fuse board for injector banks, fuel pump, MS main and switched power, idle control valve.
-Bosch brown top injectors: 35lb/hr @ 2.5 bar
-Custom made fuel rail, injector cups, and distributor blanking plate from 924.org member.
-Generic adjustable fuel pressure regulator with gauge
-Generic 1/4" nipple fuel filter
-Modified & custom aluminum intake manifold
-Ford 5.0L 65mm throttle body, with TPS & IAC
-GM intake air temperature (IAT) and coolant temperature (CLT) sensors
-Ford EDIS-4 module, coil pack, VR sensor, trigger wheel, and plug wires
-Custom made spacer to mount crank trigger wheel
-All sorts of brass fittings & hose barbs
-S & B cone air filter and breather filter
-Forge Motorsports blow off valve
-944 Turbo modified intercooler
-Zeitronix wide-band o2 sensor (with data-logging)
-Exhaust gas temperature (EGT) probe (interfaces with Zeitronix)
-Lots of silicone tubing & elbows
-Lots and lots and lots of wiring!

This stage of the rebuild is still ongoing. One of the biggest obstacles has been to have a new intake manifold plenum made up and welded to the stock runners. I would like to have had more space between the plenum end and the #1 runner, but the alternator squeezes things down. I could have given the runner a little more space, but I wanted to err on the side of caution - once it's welded, there's no going back! 

I kept the runners as long as I could manage and they ended up being 18cm long. The plenum is attached at a slight angle so that the runners would all be the same length - since some are bent and others are not. The resulting length differences are within about 5mm.

I had to remove the brake light pressure switch under the brake master cylinder. I also need to still re-bend the brake lines leading into the MC to make room for the throttle body. Off of the throttle body will be a 3" to 2.25" 90 degree elbow. From the elbow, it's a short straight shot to the modified intercooler outlet.

(944 TB on left, Ford TB on right)
The throttle body is from a Ford 5.0L Mustang and measures out to 65mm. The pedal shouldn't be too sensitive, and I have little doubt that it will be a restriction either. The TB comes with the generic Ford throttle position switch, and a simple on/off idle control valve for a higher idle on cold starts (you can see the valve hanging off the side). I'll have to think of something clever in order to attach the linkage...

I had the firewall-side plenum endcap drilled and tapped for two 1/4" vacuum fittings (feeding the MAP sensor, BOV, boost gauge, and wastegate control), a single GM IAT (intake air temperature) probe, and a brass barb that will feed vacuum to the brake booster.

The 951 intercooler has been modified on the inlet side. The inlet has been moved from the front of the IC to the side. A 2.25" 90 degree elbow will align the inlet w ith the turbo outlet. I'm amazed at how well everything lines up.

The 931 vented nose panel will feed fresh cool air over the intercooler in this placement. There is a sheetmetal diverter in the nose that needs to be cut out. I'll also make a simple shroud to direct all of the air coming in the vents through the IC. Very simple and neat.

The other big obstacle was how to mount the Ford EDIS crankshaft trigger wheel on my crank pulley. A machine shop on the South side of Boston pressed and tack-welded the trigger wheel onto a steel spacer which was run through a lathe to sit inside my crank pulley almost perfectly. Absolutely excellent work!

I jumped on a rennlist group buy for my Forge Motorsports blow off valve (BOV). This will replace the funky factory design that is integrated into the turbo compressor housing. The Forge piece has multiple springs used to set the opening pressure. I'll probably just let this vent to air, unless it's too obnoxiously loud...

The fuel pressure regulator is a generic adjustable piece with an integrated gauge. A vacuum signal is used as a reference to keep the pressure differential on both sides of the injectors even.

The exhaust manifold was drilled and tapped for the EGT probe. The placement is actually in the secondary manifold chamber which leads back to the wastegate. Not the best spot, but it will give me ample warning if the combustion temperatures start climbing too high. This is something I really could have made good use of on the last build!

The fuel rail was made a fellow 924-guy from the 924.org web board. Simple and functional. The Bosch injectors almost snap into place in the modified injector cups, and the fuel rail sits down on them with perfect spacing. Some folks are estimating that the 35lb s/hr injectors might run out of steam as I approach the 250hp mark. Theoretically, they should be running at a reasonable duty cycle at max output, but it's something I'll be keeping a close eye on.

I felt that having a wide-band o2 would be much cheaper than hitting the dyno 100 times in a row. It will also alert me to any sudden problems while on the road. It's certainly going to make tuning in the MS fuel tables much easier.

The Ford EDIS installation will let me program my own timing tables based on rpm, MAP, and boost. Not only do I get rid of the old wobbly distributor and free up a little parasitic drag, but the timing will be fully programmable. The EDIS has the bonus advantage where if it fails to get a signal, it will just fire at 10 degrees advance in a "limp home mode". Ford does manage to do some things right and cheap! 

MISC PICS

This photo shows how the fuel rail sits with the stock charge tube plumbing. It's close (touching in fact), but I believe it can be made to fit. I'm not worried about it since the stock charge tube will be replaced by plumbing directly from the turbo to the intercooler.

This page is just to bring everything together in one place. Most of these pics I've lifted from websites & discussion board posts. I hope it showcases some of the excellent craftsmanship going on with these old 931's.

Another intake:

The stock GTR intake:

The stock GTS intake:

The Latest Carnage grr..

Latest working ignition map

Extras for sale:
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