The Ultimate Guide to EFI, Part 1 – Don’t fear wiring EFI in as Haltech makes it easy!

One of the biggest individual projects I’ve undertaken is fitting fully programmable EFI to my ’64 Pontiac’s engine. One thing which is important to point out is that EFI isn’t a magic bullet to cure car set-up problems or find a million horsepower – a good standalone ECU makes it easy to get a good tune into your engine, and makes it easier to cold-start, have smoother part-throttle, and more.

I had a rebuilt Carter AFB four-barrel carburetor on a new intake manifold all set-up ready to drive when I realised I wanted the easy starting, improved fuel use and cleaner running from EFI.

This post will detail the sensors and electronic side of converting a car to run EFI, as I’ll cover the fuel system and intake manifold in later posts.

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I purchased a new Haltech Elite 950 ECU to run the show. While a “bolt-on” system from Holley, FiTech, FAST and others seem appealing the reality is they aren’t a patch on proper port-injection, which involves having injectors squirting down into the intake ports of the engine.

I also wanted to run two four-barrel throttle bodies for the vintage “dual quad” muscle car look. At the time I embarked on this journey the only way for me to do this was by using the Haltech and if I had my time over I’d definitely stay with the Haltech product.

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On the face of it, changing your car to EFI is a complex and expensive swap, but is easy to knock over if you are methodical and read up a lot as you go (thank you, King Google!). Wiring is definitely NOT my forte so I was stoked with how simple the Haltech Premium wiring loom that came with my Elite 950 ECU is.

This diagram (below) is the God sheet. Haltech sell a Basic and a Premium wiring loom, and I can’t recommend the Premium loom enough as it comes set-up with a fuse box and relays. Haltech have really saved the bacon of all of us who are pretty good at the old Shadetree Mechanic schtick, but are still a fair way short of professional status.

After working out what wires go where, I noted what each wire was for and loosely grouped them together into their basic formats. So i had the 8 fuel injector wires together, the four wires going to the coils together, the wires going to the throttle bodies (idle air control, throttle position sensor, intake air temp, etc).

The next step from this is to take the loom into the cabin, mount the ECU and push the various wires needed to run the different functions through as they’re required. I’ll do this once I get my intake manifold back so I can work out how much wire length I need for the various sensors on my FAST universal throttle bodies.

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The ECU needs information from a few sources, and my F.A.S.T #304154 air-only throttle bodies use generic GM sensors from Delphi. These include intake air temperature (IAT) and throttle position (TPS). The Haltech 950 can’t control the stepper-type Idle Air Control (IAC) sensor that comes with these throttle bodies so I blocked that port off and found a two-wire Bosch item that I mounted on the firewall.

Instead of a distributor I am using 8 coilpacks from a 5.7-litre LS1 Chevy V8. This should be a better, tidier solution to firing my 400cui Pontiac V8. The coilpacks are mounted on a pair of cool brackets from Australian company Tuff Mounts, which I will custom-mount in the engine bay once I have my intake manifold back from being machined to fit the injector bungs as this gives me the best idea of how much space I have around the motor.

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Removing the distributor meant I needed this billet-machined oil pump drive from BOP Engineering in the USA. Wade made this piece up and it could also be used as a cam sync if I wanted to go full sequential ignition later on down the track.

The computer also needs to know where the engine is in its firing cycle. To sort this out I had to bolt a toothed wheel to the crankshaft, and point a sensor at it to read the missing teeth, giving the computer a reference point for Top Dead Centre on cylinder #1. I had a fabricator machine the centre bore of this Holley universal 60-2 wheel to suit my hub balancer.

Haltech sells this Hall Effect crank trigger sensor and it was super-easy to wire-up and fit, which you can see in later updates.


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