We’re still at the AETC conference, and one of the presenters is Bob Morreale of The Tuning School. Lots of the information Morreale presented was specific to professional engine tuners, but he made a few great points that will be useful to practically any car guy.
One interesting point Morreale made is: “The scanner cannot lie.” This may seem absolutely untrue at first, but Morreale’s point is that the scanner can be wrong, but it cannot lie. “If the scanner is telling you it is negative 200 degrees outside,” he says as an example, ” then you know you have a sensor going bad or something else is really, really wrong, but the scanner is always going to give you the information it gets. It wont’ lie to you.”
As a real life example, Morreale tells about a 2002 Camaro SS that came into his shop for tuning. The car had had new cylinder heads, camshaft, headers and an intake installed by a reputable shop, and a visual inspection said everything looked great.
But after firing it up on the chassis dyno the car idled terribly. A quick look at the scanner showed that the MAP was reading atmospheric pressure at idle–which should never happen. At idle the engine should be pulling against the closed throttle blades creating a vacuum inside the intake manifold. It turns out that a plug hand’t been installed in the back of the intake manifold creating an absolutely huge vacuum leak. Because it wasn’t easy to see, you may assume that there was a problem with the monitoring equipment or the software, but the scanner cannot lie. Until you get the parameter where they should be, there is no point in tuning the car. Find and fix the problem, then move on to making power.