Black Magic: The Art of Finding an
Aftermarket Calibration Y
ou know, this profession sure has seen some changes over the years. Not too many years
ago the only thing you had to worry about was building a quality transmis- sion. Today, you can build the best unit in your county, install all the right parts, perform the repair like a deranged per- fectionist, and still the unit comes back with a failure. This scenario is starting to play out
all over the country. No matter where you live, no matter how good you are, many technicians are seeing comebacks they’d have never seen just a few years ago.
It’s an interesting situation because
the technicians at the dealer level also experience this problem. The problem has gotten so bad that manufacturers have taken action in an attempt to limit their exposure. So what’s the source of these prob-
lems that seem to have no cause? It may be an aftermarket calibration. Most shops are aware that there are calibrations available that significantly increase engine torque over the stock calibration, but how does one find them, and why would they cause a problem? The powertrain is designed to
handle a specific amount of torque. In fact, many OEMs detune their cali- brations due to the limitations of the stock drivetrain. While the aftermarket calibrations are typically designed for “off-road use only,” we’re all aware that these calibrations aren’t remaining off road. Many of the vehicles you’re
called upon to repair have performance enhancing software installed. It’d be nice to have a method to identify those non-OEM calibrations. On late model
20
by Steve Garrett
members.atra.com www.atra.com
Figure 1
Figure 2
GM vehicles, you can do so by check- ing the Calibration Verification Number (CVN). To locate the CVN for a vehicle: 1. Access the GM TIS2WEB web site
located at
http://tis2web.service.gm.com. You can also search GM service and choose: • GM Service and Parts Operations, then…
GEARS March 2012
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