Anything about Ford EEC tuning. TwEECer and Moates questions dominate, but there's some SCT and OBD-II knowledge too.

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David Claflin
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Making a minimalist EEC-IV harness

Post by David Claflin » Fri May 24, 2024 4:25 am

In an attempt to make his mustang as light as possible a buddy of mine is thinking of removing as much wiring as possible from his EEC-IV harness and still retain functionality of the EFI system. I've got a chip in it, so the TAB/TAD, and EGR are turned off, so those wires could be pulled. I was thinking the fuel pump relay and fuel pump cut off at the back of the car could be moved closer to the EEC processor to shorten the length of the wiring. What else do you think could be eliminated and not create driveability issues?
1990 LX/A9L/347, 205TW heads, mild cam, TFS-R box, 1 3/4 longtubes, 3"exhaust, T5, 4.56
1985 LTD LX, A9L, ported Performer RPM, ported Holley SMII,1 3/4 longtubes, 4.10, T5trans, mach 1 brakes.
1986 coupe, VM1, former FHP car, stock shortblock, ported TW heads, VIC Jr EFI. 4-holeTB, 1 3/4 longtubes, 3" exhaust, T5Z, 4.88

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Re: Making a minimalist EEC-IV harness

Post by cgrey8 » Fri May 24, 2024 6:09 am

The motivation here is intriguing and confusing at the same time.

This person is interested in shaving weight so badly that they are seriously looking to reduce a few ounces of copper and plastic, but they are still using an EEC-IV to control the engine which is likely of the same era? Is this just some kind of personal challenge or are there real stakes involved with this motivation? I'm just thinking there has to be far more productive places to look to reduce weight (and drag) than snipping a few wires out of the vehicle. For instance, aluminum heads/block, removal of sheet metal parts, replacing steel suspension components for aluminum ones, etc etc.

But as to the actual question, I guess if you just really wanted to reduce wire length, you could get crazy and relocate the EEC up closer to the engine and shorten every wire in the loom. You would need to build some kind of water-resistant enclosure for the EEC to mount in. Many EEC-V trucks like mid 90s era Rangers and Explorers located the EEC in the top of the firewall, directly above the engine which makes for a pretty short wiring harness as compared to the Fox body looms. Here's an example:

Another HUGE weight cutting option would be to ditch the lead-acid battery for a lithium battery. Lithium batteries are so power-sense you can fit the cranking amps of a 20lb battery into something you can hold with 1 hand without straining. That alone would get you FAR FAR more weight-loss than you could possibly get trying to cut copper from the vehicle.
...Always Somethin'

89 Ranger Supercab, 331 w/GT40p heads, ported Explorer lower, Crane Powermax 2020 cam, FMS Explorer (GT40p) headers, aftermarket T5 'Z-Spec', GUFB, Moates QuarterHorse tuned using BE&EA


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