Part Twelve: More Electrical Current

While some might think getting twelve separate articles out of one project might be a challenge, you’ve got to consider the starting point of that project and the final end goal. Take Project Obsessed for example here, when we took ownership of this 1996 Ford F350 last year, it was basically stock with nothing more than a 20-year old flash tuner, some outdated cosmetic upgrades and a terribly riding front leveling kit. The old 7.3L Power Stroke under the hood was still running strong with 224,000 miles on it, but like the rest of the truck needed quite a bit of attention if it had any aspirations of hanging with a new 400+ horsepower 6.7L Power Stroke.

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An often overlooked piece to the performance puzzle is the efficiency and oomph in your electrical system. With all the aftermarket bolt-ons we start adding to our trucks, making sure you have a healthy starter and alternator is an important piece. Cue Xtreme Diesel and their HD Series line of High-Output Alternators and Gear Reductions Starters.
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The XDP Gear Reduction starter is built from brand new pieces, rather than being a remanufactured part like you’d find locally. A few advantages here is the lack of a need to return a core, and the smaller more efficient motor and reduced gear that increases torque from the starter.

Now over a year into the build and upgrades we find ourselves well past our 450-horsepower goal thanks to some bigger injectors, a modified turbocharger, electric fuel system and a host of other bolt-ons. We’ve been able to keep the classic look with some newer front fascia pieces and we improved the ride quality with a Reverse Shackle and Super-Duty leaf spring swap on the front axle. Really, with a whole lot of elbow grease, countless hours in the garage and more dollars than you’d dare tell your wife you’ve spent, this old Ford is about the nicest one on the block. With all that said, we still aren’t quite finished with the build and still have a few planned upgrades, including some brake and cooling system upgrades next month. This time, we’re focusing on the electrical system, installing an all new gear reduction starter and high output alternator along with a high voltage high current Injector Driver Module.

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With what appears to be the original starter from 1996 still bolted to the engine, it’s obvious it’s taken some abuse with a bent terminal and a couple hundred thousand miles of road debris, grime, and corrosion.
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On the bench you can see some pretty obvious differences in the original starter and the new XDP unit. XDP’s starter comes with a full one year warranty and is coated in a durable wrinkle coating that not only looks great but helps fight against corrosion as well.

With all new injectors and an electric fuel system running dual factory Super Duty fuel pumps, we wanted to make sure the electrical system was up to snuff. Not knowing the history on the components on the truck (like the alternator that appeared to be the original from 1996) making some updates just seemed like an easy choice for this build. We weren’t willing to spare expenses anywhere else along the way, so why fall short on the electrical system? We are going to be traveling far from home, towing throughout the year, so it’s a nice piece of mind knowing an old starter or alternator won’t leave you stranded somewhere.

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Could this High Output alternator have been a better fit for this build? Not only does it bump our amperage to 200-amps to support our aftermarket electrical accessories, but the standard black wrinkle finish ties in perfectly with our textured coated black intercooler piping.

The high output starter from Xtreme Diesel offers a 200-amp output which is a substantial improvement over the factory unit and will ensure we have enough power to run any aftermarket components like those new fuel pumps and our mildly pumped out stereo system. As an added bonus, XDP uses stealthy black wrinkle coat on the alternator that looked incredible under the hood next to our textured black intercooler piping. XDP also tests their alternators during the assembly process to ensure they work as they should before shipping, offer a full 1-year warranty and because they are brand new units, there is no core required.

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The High-Voltage, High-Current Injector Driver Module from Diesel Technology of Chattanooga increases output to the injectors from 110-volts to 140-volts. This actives the injector quicker, holds the injector’s poppet valve open more firmly, and keeps it ‘on’ slightly longer. Meaning better throttle response and snappier acceleration.

Like the alternator, XDP also did their homework when it came to their gear reduction starters for the 7.3L Power Stroke application. The smaller motor on the starter not only spins faster than a factory replacement would, but it’s more efficient and draws less amperage. With the gear reduction within the starter, it offers a much higher torque to spin over that big engine even though it’s about 1/3 the size. Matching the alternator, it also comes coated in a black wrinkle coat for good looks and better corrosion resistance and has that same one year warranty.

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The Injector Driver Module (IDM) is often mistaken as the Powertrain Control Module (PCM) as they look very much the same. However, they are quite different and located in slightly different locations with the IDM easily accessed on the inside driver fender well. The PCM is tucked away a bit more through the firewall inside the cab.

Going back a few months on this build, you’ll remember that we installed a new set of injectors from Full Force Diesel. We had opted for their 205cc hybrid injector with a 30% nozzle size, which they had recommended for our application. It would offer great towing performance, with low smoke output and easy EGT control, while having enough fuel to support upwards of 450 rear wheel horsepower. Looking to give those injectors the best chance at efficiency and complete the final piece of our ‘performance’ puzzle we turned to Diesel Technology of Chattanooga (DTC). Owner, Johnathon Ryan, has been in the 7.3L game just about as long as anyone, and has seen just about everything under the sun when it comes to this engine platform. His knowledge of the engine, how it works and what makes it work better will impress you after just a matter of minutes talking with him. We’ll use direct quotes from him to explain how the IDM works and what they do to improve it:

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Swapping out the IDM is really a 5-minute job with just a few mounting bolts needing removed and the single 10mm bolt on the harness connector needing loosened. Obviously, you’ll want to make sure there is no power being run to the IDM, meaning no key in the ignition and the batteries disconnected.

“The Injector Driver Module (IDM) is just an electrical box, computer, that fires the injectors in response to commands from the Powertrain Control Module (PCM). The IDM uses a Peak-and-Hold method to control the current to the injectors. During the ‘Peak’ period, it supplies full current to the injector solenoid so it experiences the maximum electromagnetic field to fully open the injector’s poppet valve to fire the injector. A factory IDM should start at 112-volts and peak for 525 microseconds, as that capacitor discharges the voltage will drop to around 93-volts at the end of its peak. The IDM then begins to rapidly switch the current to the injector on/off at 12-15kHz, this is the ‘Hold’ portion of the process as it holds the injector open. 400-microseconds after the peak has ended, there is a break gap in the holding pulses. That break gap is a non-intentional design parameter within the circuits design. If that ‘gap’ period is short enough, the IDM works as it should.

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On the bench, you can see the difference between our aged and slightly corroded IDM and the newly rebuilt and upgraded IDM from DTC. Since these are just a modified version of a stock IDM, it installs in place just like the original.

Average gap time ranges from 125-150 microseconds on a standard 120-volt IDM but can increase as the IDM gets older and starts to get tired. If that gap grows to over 300-microseconds, injector performance will start to suffer and even misfire. At 400-microseoncds, the gap is actually longer than the actual injector turn on time and the IDM won’t have the energy to turn the injector on.”

We opted to send in the IDM from Project Obsessed to be tested, rebuilt, and upgraded so we could compare data before and after. Ryan has been working on IDM’s since the early 2000’s, so you can be sure he knows what to look for and has the knowledge and experience needed in such a daunting looking computer piece. Our gap tested at 364-microseconds, which is on the weaker side, but common for the 1994-1997 model year trucks. At this point, DTC started the rebuild process where they replace 15-20 components within the IDM to make sure its back up to snuff and ready to go for thousands of trouble free miles. Once completed, the IDM is run through 13 different tests to ensure it’s working as good or better than when it was brand new.

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The high voltage, high current IDM from DTC was the final upgrade for Project Obsessed performance parts. With aftermarket performance injectors, making sure they get a strong consistent signal from the IDM/PCM ensures we’re getting the most out of our fueling modifications.

Now, onto the upgrades for the IDM. DTC first makes some adjustments to increase the voltage to 140V, which has been a popular modification since 2004. While increasing the voltage output by itself can increase injector performance, DTC also performs some upgrades within the IDM to increase the current. By making both voltage and current changes, they can ensure the IDM is sending the strongest and most efficient signal to the injectors so the injector can maximize on-time and injector pulse width duration. The IDM is then tested on a running engine for 60 minutes at 3000-rpm and 3.0 milliseconds of injector pulse width. If you were to run your engine that hard in the truck, you’d melt pistons for sure. These tests ensure the IDM will hold up to the sustained heat and demand from towing applications.

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Inside the IDM you’ll find a whole bunch of stuff that next to nobody can understand. Is this what a 1998 Mac computer looked like? Or is this a new iPhone 11? We can assure you that the team at Diesel Technology of Chattanooga know exactly what all that is and how to get the most out of it.
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Jonathon Ryan and Billy Crush at DTC have been working on IDM’s for over a decade and have all the equipment in-house required to not only rebuild an IDM, but test every operation both stock and upgraded to make sure you’re getting the most efficiency and performance from your IDM.

While a modified IDM isn’t going to make a massive improvement in power or performance, with the level of modifications done to this truck and the age of the factory IDM, these are changes that will be noticed. After driving the truck, we did experience a better idle and significantly better throttle response. The engine feels and sounds healthier and has a peppiness that’s hard to describe without driving it. The high voltage high current IDM pretty much rounds out our performance upgrades on the old truck, and we’re super happy with drivability from the truck. Next month we’ll upgrade the cooling system and brakes to handle the abuse of heavy towing a little better.

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