First of all this is a LSx swap car (fox body mustang). Car has been together for a couple of years and never had this problem. Now it seems I can't make a single pass without the datalogger stopping before/during the pass. The car is pretty quick (5.60's in the 1/8th, turbo charged), so having reliable data logs is very important. I've never had this problem in any other cars I've tuned.
I rewired the ODBII port completely (ran a new serial data wire directly from the PCM, new + source and ground) and the data log has still yet to make it all the way down the track before shutting off. It is the strangest thing but something causes the scanner to stop logging and when it does this it will say it can't find the interface if you hit the play button (scan) again (you have to pull the usb out and put it back in).
I've only been able to recreate the problem twice in a non-race setting (obviously when blasting down the track I cannot look at the data logger), and both times it seemed like the data started pausing a bit before it finally gave up, like the numbers on the data logger would lag a few times then it'd stop. I have never experienced this in any other cars, but I am 100% sure the wiring to the odbii port is perfect. I thought I had the issue narrowed down to the brake switch input into the PCM as the data logger seemed to lag when I'd step on the brakes, but I removed that input and it did it again on the next pass.
Any ideas on what to check now. I have now raced 3 or 4 weekends without a single good datalog and with a car this fast I am weary of that. Car does have some electronics in it, line lock, transbrake, co2 boost controller, etc., but none of those are on the same ground and I can't recreate the problem with any of them. It seems to really only want to do it when I am making an actual pass.
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Originally Posted by 03Sierraslt
