[DorkMissile]

There are parameters to take into consideration when measuring "boost" thru the OBD data.

First off - boost is a measurement of ambient air pressure subtracted from MAP. If you have a relevant MAP sensor that is in a good location, and have a good source for ambient pressure, then you can actually get a good boost reading.

Most GM cars measure ambient pressure at the MAF sensor (it is part of the MAF). So if you are running a CAI with little to no restriction, and the MAF is somewhat close to the inlet for the intake, it should be relatively good. The problem is that most MAFs are put much closer to the engine than the air filter, as the MAF is more important to the factory calibration.

For example, on my SS, after adding my ECS kit, the MAF moved to what is probably the worst place in the system to measure the ambient pressure, on the outlet of the air/air into cooler. By the time the air was measured, it was pulled thru a filter, run thru a blower, thru about 30" of piping and across 30" of intercooler. It had squeezed, heated, cooled and slowed by the time it got to the sensor.

Hense the reason why people run "Baro-Breakout" harnesses. My car is equipped with said harness. Upon adding the S/C, my tuner had me put a 2Bar map in the intake to take place of the factory 1Bar. I then took the 1Bar, plugged it into the Baro-Breakout harness and mounted the sensor in front of the driver's side valve cover, in very near proximity of the intake the air cleaner.

When first setting up the iBanks - it is smart enough to see the additional MAP sensor, and it will allow you to select the added sensor instead of the MAF to measure Boost (you get both actually, you just pick which "Boost" you want to look at.

I would deduct that it is fairly accurate measuring the added sensor, you can even see the added air density from the speed of the car (building air pressure under the hood) where as the MAF system does not. At 80mph, it is almost .7 or .8lbs different.

When asking my tuner if it is accurate enough, his answer was "its what your tune is reading to calculate it's parameters, irregardless of what gauges you are watching"

[wookwook]

the glorious thing about the 2T is that it is a weather station on wheels, built in 02 and all. 2T being a mini-me ZL1 generally doesn't have the radical mods for the most part, those owners haven't really tended to add much here, yet. but- I tend to trust that the engine/ecm is very good at calculating its requirements and reporting the digits to the GUI. Its good enough to have for relative comps if your tuning in a controlled window, which usually it what people get. Over the seasons, there definitely are deltas in air density that does reflect in the logs. That's why there are SAE advocates, and dyno and practical road checks to measure against also. But in the end, I use VCM and it reports exactly what the ECM is thinking. I use that term loosely.