Holley EFI

[eschaider]

Gary,

Lopey idles and vacuum considerations are meaningful considerations for carburetted engines. They make no difference for EFI. In fact the EFI will somewhat smooth out your loopy idle and improve low speed throttle response — although that may not be what you want.

What you want to do before spending money on EFI is to purchase some reading books on EFI systems, which means you will probably spend around $50 on various candidates. Get familiar with the capabilities of EFI systems and decide which capabilities are important to you. Next thing you want to do is hunt down EFI providers that offer those capabilities. Rank them according to cost and capability. Decide how much money you want to spend on the conversion. Pick the system that matches you list of important features and meets your budgetary goals.

One of the most important capabilities you will want is a Mass Air Flow (MAF) capability. There are three fueling models for EFI. Alpha-N, Speed Density, and Mass Air Flow. the only one that will allow you to move 7000 feet vertically and still properly fuel your engine, without retuning, is the MAF based system.

Most aftermarket systems are speed density. If you experience a 1500 foot or more change in altitude, a speed density system will benefit from being retuned. Speed density system providers will either suggest the difference is not worth retuning for or suggest the speed density logic can accommodate it. Both suggestions are wrong.

By the time you get to 3000 feet your engine will feel like it has lost considerable horsepower, partly because of thinner air and partly because of incorrect fueling at that altitude. At 7000 feet you will think you need a tow truck.

The other thing to be sensitive to is sensors. Most aftermarket suppliers like GM sensors. In fact they like them so much they repackage them in their own proprietary bubble packs and boxes and reprice them significantly above the over the counter equivalent GM sensor price point. You want to avoid these types of providers.

If you are electrically handy you will enjoy building you own wiring harness for an aftermarket system. If you are not this will be a royal PITA. Some EFI manufacturers will work with an OEM engine wiring harness saving you all the build effort. By work with, I mean they will plug right into the OEM under dash connector on the under dash harness that connects to the engine harness.

Holley does offer some EFI systems that can make use of selected OEM harnesses. You should look at them. You should also look at the DIY Autotune Plug and Play systems that plug into a stock Ford Mustang harness. DIY Autotune will be less expensive and come with a base tune to get you started. BTW they also support MAF based fueling and use Ford OEM sensors which you can buy directly from Ford.

Here s a link =>MS3Pro Plug and Play. Pick the Mustang ECU closest to what you are doing and the ECU for the year and engine harness you decide to use.

I forgot to mention if dashboard support is important to you they support many aftermarket dashes/displays such as Racepak, Race Technologies, AiM Sports, AEM, Dakota Digital, Autosports Labs, Perfect Tuning, and OEM Ford New Edge dashboards.