Didn't really see this anywhere else so I figured I'd post it. Usually the discussion is about replacing the idle switch in the TPS and not fixing the WOT switch. Anyways, it's not exactly hard to figure out once you crack the TPS open, but figured I'd post how I repaired the WOT switch in my TPS.
The main symptom that led me to check the TPS was a noticeable loss of power at WOT above roughly 4500RPM. Still pulled to redline, but noticeably bogged. I have yet to reassemble/retest, so it's possible there are other root problems in my case, but the TPS WOT signal was definitely something that was failing.
For reliability it was recommended to just buy a new TPS -- which I've done and agree is the reliable way to go. When buying a spare one, I was told by the parts guy at the dealership that there are exactly 3 of these left (now 2) in the US and NLA from Germany. I'm guessing you can still buy the Bosch or FACET versions, though. The Bosch ones (which usually sell for $50-75) are all out of stock in the places I've looked online. The only ones I found available were the FACET one or the Genuine BMW one -- the latter selling for $100-150.
Once I bought one, I figured I'd take a look inside mine and see if the fix for my missing WOT signal would be obvious/easy. In my case, 80% of the time I did a continuity test with my DMM, I'd get a fail. Occasionally, though, it would pass.
After opening it up, the 2 points where the flex-arms connected to the pinouts had a cracked solder connection. I separated the pinout connector from the arm a little more and soldered the two together. The photo is from after I separated the two -- before that it wasn't obvious the two weren't connected.
Make sure to avoid a cold solder by heating up the pinout connector / arm (I used a flat-tip soldering iron) and letting the solder flow through direct contact with those pieces, rather than making contact with the soldering iron tip. Also note that, arguably, the better way to do this is to use needle nose pliers to pinch the pieces together and reheat the connector to get the original solder to reflow. Might be a cleaner approach (maybe even add some new solder to the mix).
Also, I applied some excess solder to help keep the connection together.
The fix resulted in my WOT signal working. Now I'm just hoping that this resolves my high-RPM bogging problem. :)
Som
The main symptom that led me to check the TPS was a noticeable loss of power at WOT above roughly 4500RPM. Still pulled to redline, but noticeably bogged. I have yet to reassemble/retest, so it's possible there are other root problems in my case, but the TPS WOT signal was definitely something that was failing.
For reliability it was recommended to just buy a new TPS -- which I've done and agree is the reliable way to go. When buying a spare one, I was told by the parts guy at the dealership that there are exactly 3 of these left (now 2) in the US and NLA from Germany. I'm guessing you can still buy the Bosch or FACET versions, though. The Bosch ones (which usually sell for $50-75) are all out of stock in the places I've looked online. The only ones I found available were the FACET one or the Genuine BMW one -- the latter selling for $100-150.
Once I bought one, I figured I'd take a look inside mine and see if the fix for my missing WOT signal would be obvious/easy. In my case, 80% of the time I did a continuity test with my DMM, I'd get a fail. Occasionally, though, it would pass.
After opening it up, the 2 points where the flex-arms connected to the pinouts had a cracked solder connection. I separated the pinout connector from the arm a little more and soldered the two together. The photo is from after I separated the two -- before that it wasn't obvious the two weren't connected.
Make sure to avoid a cold solder by heating up the pinout connector / arm (I used a flat-tip soldering iron) and letting the solder flow through direct contact with those pieces, rather than making contact with the soldering iron tip. Also note that, arguably, the better way to do this is to use needle nose pliers to pinch the pieces together and reheat the connector to get the original solder to reflow. Might be a cleaner approach (maybe even add some new solder to the mix).
Also, I applied some excess solder to help keep the connection together.
The fix resulted in my WOT signal working. Now I'm just hoping that this resolves my high-RPM bogging problem. :)
Som
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