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​DDEC IIs Part 3: DDEC II Programming

By Fernando DeMoura

May, 2017

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I’ve never seen a DDEC II 12.7 GU program that could produce over 500 horsepower. The only thing I‘ve seen are DDEC II programs that have had their digital data tag renamed from a 430 to a 550 horsepower. This is the equivalent to selling a 430hp GU DDEC II and writing 550hp on the case with magic marker.

Over the last two months I’ve been studying the code I pulled from the eight DDEC IIs I purchased. The programming procedures required to program a DDEC II are from back in the days when engineers got excited about using the word “Digital” to describe their work. DDEC II programming is simple but raw and much like my test bench, designed to be used by the engineers who created it. The programming directly references analog to digital conversion, serial communication protocol and proportional integral derivative controls. These are old but fundamental technologies which have formed the building blocks for modern control systems. Over the last year I’ve grown more and more old school when it comes to electronics so I feel fairly comfortable with the DDEC IIs software design.

Early bench testing shows that this ECM will do what it is told very consistently and given the simplicity of its programming that’s not a huge surprise. I created a test only DDEC II program to establish the limits of the ECM hardware. I was able to produce a large enough injector pulse to make roughly 1200 horsepower if it were to be used on a 02 Series 60 but this ECMs production years were from 1988- 1993 so this program will never be tested on an 02 S60 and not likely any other S60 because of the damage it could cause. The MY 88-93 12.7 GU and 88-93 11.1 WU were not designed for that kind of horsepower. If this was a converted GU DDEC II 12.7 to GK DDECIII 12.7 engine I’d only suggest 550hp 1700 ft-lbs and that’s only if the owner/operator is vigilant and watches his gauges. I’ve set converted GU and GKs up with switchable programs that have one setting going beyond 650 horsepower but anyone who asks for this needs to understand the risks they run when they’re climbing a big hill and turn up that dial. I routinely repair marine DDEC III/IV ECMs with factory 12.7 800hp 2400 rpm programs. In the marine industry, an inframe every 5000 hours is considered normal for water cooled “pleasure craft” applications. In the trucking industry an engine needing an inframe after 5000 hours is considered a failure. Abnormal engine wear can take a while to detect. You usually don’t know you’ve overdone it till a year or more later when the liners start getting scored up or you start seeing lots of bearing material in your oil samples. I am ready to start offering DDEC II programs but let’s start small at first. We can always go for more later.

Written by Fernando DeMoura, Diesel Control Service LLC. www.dieselcontrolservice.com Phone 412-327-9400