Power cutout at full throttle
02-27-2004, 03:41 PM
#17
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Well, I checked the cost of an AFM, and decided to ask the help of a pro.
He installed a box full of flashing lights and digital displays, insisted that with engine off everything looked perfect, then told me to take off with him in the right seat holding the box.
After half an hour, the verdict: the TPS works perfectly with engine off, and in 1st gear. Once, it failed to close at foot-to-the-floor in 2nd, but in 3rd and above it never closes at full throttle, only at throttle off. When it doesn't close, that's when I get the power cutout.
He says the signals from the AFM look fine.
Does the TPS have a vacuum gizmo in it? That would help a bit to explain the cost :-(
Why would a car computer be programmed to cut fuel totally if a switch did NOT close at full throttle?
Should I maybe just make a very non-Porsche block of wood to go under the throttle pedal to 'solve' the problem?
He installed a box full of flashing lights and digital displays, insisted that with engine off everything looked perfect, then told me to take off with him in the right seat holding the box.
After half an hour, the verdict: the TPS works perfectly with engine off, and in 1st gear. Once, it failed to close at foot-to-the-floor in 2nd, but in 3rd and above it never closes at full throttle, only at throttle off. When it doesn't close, that's when I get the power cutout.
He says the signals from the AFM look fine.
Does the TPS have a vacuum gizmo in it? That would help a bit to explain the cost :-(
Why would a car computer be programmed to cut fuel totally if a switch did NOT close at full throttle?
Should I maybe just make a very non-Porsche block of wood to go under the throttle pedal to 'solve' the problem?
02-27-2004, 03:48 PM
#18
Rennlist Member
this is what mine does.. usually it doesnt cut out in first gear... but it does all the time in the other gears once over 3000.. does this sound like the same problem? like i said i hear a click at no throttle and dont at full
03-01-2004, 04:49 PM
#19
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Well, I found what the problem was. The TPS has two switches in it. The one that closes at throttle-off is a nice sealed microswitch; the one that closes at full-throttle is a totally open unshielded pair of contacts driven by a cam. The assembly is mounted with the actuating shaft up; the actuating shaft is sealed with a rubber O-ring. The ring was worn out, flattened, so my assembly was full of water and oil.
Break the seal to take the unit apart, clean everything, replace the O-ring with a new one, and everything works.
BTW, a replacement TPS from the local Porsche dealer is $200Cdn. The same part from Bosche is $90Cdn. Just make sure you get the right part - my TPS has 3 contacts, newer ones have 6.
Break the seal to take the unit apart, clean everything, replace the O-ring with a new one, and everything works.
BTW, a replacement TPS from the local Porsche dealer is $200Cdn. The same part from Bosche is $90Cdn. Just make sure you get the right part - my TPS has 3 contacts, newer ones have 6.
