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What's Inside a 944 Throttle Position Sensor? (Read 237 times)
jacob estes
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What's Inside a 944 Throttle Position Sensor?
May 19th, 2020 at 2:38am
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Ever wonder what is inside the $500 Porsche exclusive Bosch TPS for your 944?

  

1985.5 944 NA
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jacob estes
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Re: What's Inside a 944 Throttle Position Sensor?
Reply #1 - May 19th, 2020 at 2:54am
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Mine got filled with chocolate shake that coughed back into the intake when I blew a head gasket. It didn't occur to me that anything could get inside the sensor, but after cleaning it the first time and setting it aside for an hour I found shake leaking out of it.

When I tested the sensor originally, I had some conductivity across pins that should not. After cleaning as best I could (by spraying brakleen into the hole that receives the rod from the throttle until it ran clean and liquid stopped oozing out) it actually tested worse: the same resistance across all pins regardless of switch position.

I already got a new (generic) TPS so I figured I might as well break this one open. After reading the testing procedure from Clark's Garage and hearing the click, I was immediately suspicious of Porsche's $500 price tag for this part, which obviously is priced for supply reasons.

I think if we could source the microswitch, whatever the copper armed flex switch is called, and the plug, we could 3D print an enclosure that is either easier to clean or sealed. I suspect there is not enough demand to warrant the effort though.

If you need to replace your TPS, I am confident that a confirmed-good used TPS or a generic will perform exactly as well as the Porsche-exclusive OEM Bosch sensor.

It appears that below the plastic beneath the switches, there is another cavity in the switch that the plug is routed through. I believe I have shake in there, and I think it might be difficult to properly clean it without really breaking the enclosure.
  

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OhioTom
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Re: What's Inside a 944 Throttle Position Sensor?
Reply #2 - May 19th, 2020 at 5:49pm
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two micro switches. One for idle, one for full throttle.

Water makes them screw up badly.
  

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Dave W
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Re: What's Inside a 944 Throttle Position Sensor?
Reply #3 - May 19th, 2020 at 9:31pm
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Even worse, a lot of people have to position it so that the idle switch is never closed in order to get rid of the power-lift-shudder.
  

Dave - black 84 no longer exists. Sad 83 self destructed. All better now. Smiley
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jacob estes
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Re: What's Inside a 944 Throttle Position Sensor?
Reply #4 - May 21st, 2020 at 3:16am
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The generic TPS I ordered arrived and the unit itself is Bosch and has the same part number on it as the original.

This is very strange to me. To intentionally get the part, it is very expensive and only available from Porsche. But for 80% off, a retailer has disguised the name-brand for a generic.

Assuming this was a certain outcome, I would still have preferred to get a used one for cheaper, but when I got this one I thought I would need it sooner than it turns out I will.
  

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