Quote: Originally Posted by TunerTools
A little one I can give you (although Joey will have real numbers): When datalogging for playback and analysis, some of the readings simply aren't accurate without enough speed to capture in real time. My son just tried some logging on his car yesterday using the All-In-One and PCMSCAN and the rpms were never making it to the top of the curve as he was shifting... the play back made it look like he was shifting about 4800 when in fact he was shifting at closer to 6000. The poor serial connection just couldn't keep up.
Nice TunerTools, that's the exact kind of example I was looking for... and the results I was afraid of.
In order to loose that much detail it must be only captureing a value every half-second or so... or worse.
However, in order to complete the loop, we'd need to test the same set-up with the Mongoose cable to see if it was the serial connection that was indeed causing the bottleneck. Or perhaps it was the software (PCMSCAN) that couldn't poll and record quick enough and a faster cable would hardly help at all.
Maybe someone with a Mongoose cable and PCMSCAN can provide some input to compare to your son's experience.
I'd say a device that can't keep up with a car's many rapidly changing dynamics, such as RPMs, can't be considered a truly accurate "real-time" analyzing tool. It would be better suited for discrete diagnostics (like engine alarms) or slow-changing parameters (like temperatures).