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What I learnt today.
I got a tuning box at the weekend, was going cheap on thee bay so i thought why not. Unfortunately it doesn't have any markings or destructions, so i did a bit of fiddling and couldn't find a setting i was happy with and wanted to reset it to it's default setting, by turning the little screw. Anyways after a bit of googling and searching i found some guidelines and tried resetting it. While i had it on my desk in work i thought i'd have a go at seeing how it ticked and double check the adjustments were the right way, clockwise is more etc. So i wired it up to a multimeter and a bench psu and monitored the voltage on the sensor line while i adjusted the potentiometer via the little screw.
Anyways once i was sufficiently geeked out, I reset the box to it's default settings and at home time went back down and popped it back in the car, in the fading light, making sure all the plugs where firmly in place and cable tying everything securely. Went to move off... no power, the engine just idled, slowly increasing the engine revs... oh poop. I got out and tried adjusting the box either way a bit, but same results. So i disconnected the box and thank the gods the car was back to normal, so i drove home, leaving the car park with my tail between my legs hoping none of my mates had seem me, they love making fun of my failed projects.
Once at home I plugged the box back in and tried adjusting the box more each way, same result, engine slowing building up revs in idle and no response from the throttle. Turned the screw all the way clockwise then back a couple of turns, same result, turned it all the way anticlockwise and back a few, same result. At this point i had just about give up and decided that i must have killed the box by putting too high a voltage through the box from the bench psu. I'd done a bit of research and seen other boxes using 5v to run on so i'd assumed the same.
So i sulkily disconnected the box again, pulled out the connector from the box to the ecu... and noticed a tiny catch on one side that i hadn't seen in the dim light earlier, the plug had fit in securing and flush but with the iddy biddy tab on the side opposite the big catch. I stared at it for a few seconds then flipped the plug and tentatively pushed it back into the connector, to have it fit just as securely and flush. I slowly walked back the driver's side... feeling increasingly like a muppet and turned the car over... et voila, everything back to normal. By flipping the plug i'd turned the ground feed to the pressure sensor into the live feed, and the live into the ground, with the above results. It doesn't seem to have done any damage, thank the sweet and fluffy lord. But today I learned this:
"While reversing the polarity of anything on the starship enterprise, or the tardis (i'm told) will fix any problem... it's doesn't work to well on a vauxhall vectra c 1.9 sxi.... i don't know about other models."
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Originally Posted by Ben50n
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