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Converting a 914 to aftermarket EFI:

Why do this? If you have D-Jet now, the MPS (manifold pressure sensor) is a relatively delicate part that is unobtainable new, and cannot be reliably rebuilt (the diagphram, which is the part that goes, is made of some material no one has successfully reverse engineered). The MPS is the heart of the D-Jet system, so when it goes, you stop. The rest of the system is pretty robust and more or less standard issue. Using an aftermarket ECU, you can replace the stock "brain" and the MPS with modern, solid-state parts that are readily available. You'll also gain tunability in the bargain. If you have L-Jet, you gain tunability with an aftermarket system, though there's no compelling reason to switch if your L-Jet system is working well. If you have carbs now, you'll get more accurate fuel delivery and a system that can be tuned to work even with an otherwise stock engine, which will restore good gas mileage. Carbs with the stock cam usually get no better than 20mpg in town, where an EFI engine can get 30mpg.

Available ECUs: a good number have been tried on the 914 with good results: Megasquirt, the DIY system; Perfect Power; SDS. The system from Link is currently being installed. I'm guessing both Haltec and Electromotive have been tried, but don't know any details. All of these systems are speed-density (manifold pressure/rpm as primary signals) with a throttle sensor for acceleration enrichment and decel cutoff. The SDS and MS units can also run in alpha-N mode (throttle only, no manifold pressure). The MS can also run in MAP only mode (no throttle sensor, MAP used for accel/decel enrich/cutoff).

The SDS system costs about US$1100 for the minimal system (ignition control through the distributor), with a harness and some sensors. This gives programmable fuel and ignition timing, using an MSD or other CDI box to fire the coil. There's a multi-coil waste spark option available for more money.

The Perfect Power system costs about $700 for the PRS2, which is their bottom of the line unit. That price includes a harness. It can do waste-spark using multiple coils.

The Megasquirt unit can be purchased as a kit for about $100, or bought pre-assembled for $250. Full schematics and code are freely available, so if you're particularly handy with electronics, you can build the unit yourself using whatever parts you can get at whatever prices you can manage. $100 seems to be a reasonable minimum, however. It can handle ignition control through an MSD or other CDI setup much like the SDS, plus many other ignition options, though they're all roll your own, at present. The price quoted above does not include a harness or sensors.

By far the easiest way to do the conversion is simply to use stock injection parts for the manifold, throttle bodies, injectors, and plumbing. If you're converting from carbs, it's cheaper to buy a D-Jet setup than it is to modify the carb bits. A complete D-Jet system can be had for about $100, and a pair of Weber IDFs with linkage and manifolds can be sold for $400 on Ebay.