pufferfish
Supporting Vendor
Well, my latest mission was to figure out how to trick the TPMS computer into not tripping a code when i use my track wheels (which have an aftermarket setup with a readout in the cockpit). i did some experimenting to find out how it works.
first the facts:
the TMPS sensors need to be trained to work with the puter.
given about a 2 hour drive, i know they will relearn a previously learned set.
unsure if a set that was never trained to the specific car will be able to relearn.
ford sells a doodad that looks like a keyfob that will train the sensors to the car in about 2 minutes.
training the sensors with the doodad does not require them to be under pressure.
getting the puter to relearn a previous set may or may not require them to be under pressure.
the solution:
a pressure vessel you put the sensors into. there are lots of folks across the internet that have created a "TPMS bomb" from PVC pipe. i tried this and it worked...until i found out there was a slow leak from the glued joint. once you glue that stuff, you need to start over if the glue didn't seal it completely. there is also an issue that explains why they call it a "bomb". there are reports of schedule 40 PVC exploding under pressure. this is hardly what i would consider confidence inspiring...although, im sure its a remote possibility. but schedule 40 is not pressure rated. schedule 80 is, but isn't readily available. in any case, it looks hokey. people paint them and sticker them up, but they just look stupid.
so, i set out to find a pressure rated canister. if you can find one, its either too large, too expensive or both. i just want 4 little sensors in a canister that will hold air indefinitely, oh, and it has to have an opening big enough to actually get the sensors into. so, after striking out in my search, i looked at custom. its really not easy or cheap to come up with a custom pressure vessel with a lid! i remembered that in my day job engineering machinery, we have aluminum extrusions for quick one-off frame components. you tie them all together with brackets and hardware to create a frame. its like an adult erector set. well, some times, we use these framing extrusions, which are hollow, to use as air manifolds. cap the ends and they hold air. they are rated for 150psi, so they are plenty capable. the extrusion is cheap and it can be cut to length. so i created some end caps out of aluminum, with the fixed end siliconed and the removable end having an adhesive backed neoprene rubber gasket. the extrusion has t-slots in it to allow for fastening with t-nuts and bolts, so its perfect to hard mount to the car, so it doesn't roll around. i put a schrader valve in the removable end for filling with air. after a while, i realized a built in gauge would be super handy so you can know how much pressure is in it. i found that when i checked it with a tire gauge, i would actually lose 5-10psi just by checking the pressure. there is so little volume in the vessel that a tiny bit of air escaping makes a dramatic impact on the pressure inside. so, i added a gauge to the fixed cap.
i haven't mounted it yet, but i was thinking the best thing would be to mount it to the side of my battery box in the spare tire well. keeps it out of the way and i don't need to do anything but drill 2 holes. anywho, i was thinking maybe others would be interested in one if i made more up. what do you think?
first the facts:
the TMPS sensors need to be trained to work with the puter.
given about a 2 hour drive, i know they will relearn a previously learned set.
unsure if a set that was never trained to the specific car will be able to relearn.
ford sells a doodad that looks like a keyfob that will train the sensors to the car in about 2 minutes.
training the sensors with the doodad does not require them to be under pressure.
getting the puter to relearn a previous set may or may not require them to be under pressure.
the solution:
a pressure vessel you put the sensors into. there are lots of folks across the internet that have created a "TPMS bomb" from PVC pipe. i tried this and it worked...until i found out there was a slow leak from the glued joint. once you glue that stuff, you need to start over if the glue didn't seal it completely. there is also an issue that explains why they call it a "bomb". there are reports of schedule 40 PVC exploding under pressure. this is hardly what i would consider confidence inspiring...although, im sure its a remote possibility. but schedule 40 is not pressure rated. schedule 80 is, but isn't readily available. in any case, it looks hokey. people paint them and sticker them up, but they just look stupid.
so, i set out to find a pressure rated canister. if you can find one, its either too large, too expensive or both. i just want 4 little sensors in a canister that will hold air indefinitely, oh, and it has to have an opening big enough to actually get the sensors into. so, after striking out in my search, i looked at custom. its really not easy or cheap to come up with a custom pressure vessel with a lid! i remembered that in my day job engineering machinery, we have aluminum extrusions for quick one-off frame components. you tie them all together with brackets and hardware to create a frame. its like an adult erector set. well, some times, we use these framing extrusions, which are hollow, to use as air manifolds. cap the ends and they hold air. they are rated for 150psi, so they are plenty capable. the extrusion is cheap and it can be cut to length. so i created some end caps out of aluminum, with the fixed end siliconed and the removable end having an adhesive backed neoprene rubber gasket. the extrusion has t-slots in it to allow for fastening with t-nuts and bolts, so its perfect to hard mount to the car, so it doesn't roll around. i put a schrader valve in the removable end for filling with air. after a while, i realized a built in gauge would be super handy so you can know how much pressure is in it. i found that when i checked it with a tire gauge, i would actually lose 5-10psi just by checking the pressure. there is so little volume in the vessel that a tiny bit of air escaping makes a dramatic impact on the pressure inside. so, i added a gauge to the fixed cap.
i haven't mounted it yet, but i was thinking the best thing would be to mount it to the side of my battery box in the spare tire well. keeps it out of the way and i don't need to do anything but drill 2 holes. anywho, i was thinking maybe others would be interested in one if i made more up. what do you think?
If anyone has a bad sensor or one with a dead battery they can donate to the cause, let me know and I will pay shipping!
