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Installing Isspro's Performax Instruments

Jim Allen | Writer
Posted June 1, 2010

Knowledge Is Power (Or, How To Feed Your Gauge Addiction)

"My name is Jim and I'm a gauge-o-holic!" Now you're supposed to answer back cheerfully, "Hi, Jim," and wonder why a fella would want to add nine monitoring instruments to a truck that already has factory instruments to cover the basics. Knowledge, of course! Factory gauges seldom give you a numbered reading, are heavily dampened, and notoriously inaccurate.

Mounting nine gauges in a truck usually involves a forearm-sized wiring bundle and serious mounting challenges. Well, the mounting challenges are still there, but Isspro's new Performax system cures the wiring part and adds a lot of useful capability to boot. Isspro currently has 37 gauges available for this system, with more coming.

Isspro is a name long known and revered in the diesel performance realm, but recently tapped Four Wheeler to test the waters in a new area by installing their Performax system on a gas-powered truck. Some of their gauge line is definitely diesel-oriented, but many are universal and some of the diesel stuff is useful to a gassers. For a Four Wheeler tech writer, some of these more unusual instruments will prove useful for product testing down the road, as they could be for any home gearhead with "tinkeritis."

The Skinny On Performax
The heart of Performax is the ESP, or Electronic Signal Processor, a computer that takes inputs from up to 17 different sending units and runs them though a single wire that can be daisy-chained to up to 17 gauges. Each gauge has a chip that accepts only the coded signal it's programmed to read. The other two wires are a ground and the lighting wire.

You don't have to have 17 gauges, either. If you have room for only a few, you can install all the sensors but swap the gauges in or out to monitor what you think is important for the job at the time. Diff temp, for example, isn't all that important unless you are towing, but a vacuum gauge is more important for monitoring fuel economy day-to-day. When you tow, you simply swap the vacuum gauge out for the rear axle temp.

The gauges themselves are super accurate stepper-motor types, with each step equaling one-tenth of one degree. They snap into the hole rather than using clips on the back, making them easy to move around. Plus, these instruments are LED illuminated, so they will stay lit virtually forever without onerous bulb changing. Isspro's factory is in Portland, Oregon, and they also offer custom gauge faces. For an extra charge, they can put just about any color, graphic, or even a photo onto the gauge face.

Installing and Testing Performax
We installed the Performax system and nine gauges into our long-suffering '05 F-150 HD testbed that does double duty as a farm truck. The fact that a magazine writer can do this unaided is proof of how easy a job it was. We chose to install the following instruments: oil pressure, coolant temp, trans fluid temp, rear axle oil temp, fuel pressure, volts, exhaust temp, exhaust backpressure, and air temp. The first six on the list probably make sense to you. Exhaust temperature is vital to diesel owners, but is seldom seen on gassers. We'll use it for some custom EFI tuning. The backpressure gauge will help us test exhaust systems, and air temp will help us measure the incoming engine air for testing CAI systems. That sensor will also be a "rover," and may be temporarily moved to other locations.

Mounting nine instruments was a challenge. We wanted to hide the depth of our "gauge-o-holism" by doing a clean installation. We found a few mounting products specific to the 2004-08 F-150s, but nowhere near enough to mount nine gauges in a super-clean way. We adapted and found some good generic compromises.

1. Here are eight of the nine gauges we installed, the ESP wiring, and the ESP. Each gauge kit includes a sensor, a wiring harness to the ESP and, as needed, sensor adapters. They are standard 21/16-inch-diameter (52mm) instruments.

2. Perhaps the hardest part of our job was drilling the exhaust manifold for the exhaust temp thermocouple and backpressure fitting. We removed the plastic inner fender to gain access to the manifold on the driver's side. Using a letter "R" bit, we drilled the holes with a greased bit to catch as many chips as possible.

We drilled through the last part with the engine running to blow out what chips the grease didn't catch. This is a "measure twice, cut once" type of job.


West Berlin, NJ 08091
Portland, OR 97211
Durham, NC 27701
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