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engine speed sensor
can anyone tell me the what the engine speed sensor does? Does it connect to the tachometer or dme or what?
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87na guards red(mine) 98 suburban(mine) 04 4Runner(wife's) |
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10-30-2002, 02:21 PM
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Sends engine rotational speed to the DME for processing into the duration the injectors are opened. Other inputs for the injectors are the amount of and temperature of the incoming air; AFS (Air Flow Sensor and integrated temp sensor), engine temp, and Ox sensor.
This is separate from the RPM that is reported by the reference sensor next to the speed sensor. The reference sensor signal calculates the timing in conjunction with the other inputs. The trigger signal for the coil is used by the tach. Note the speed and reference sensors are incorporated into one sensor in the 944S and 944S2's.
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Hugh - So Cal 83 944 Driver Person NOT a 'real' Porsche -- Its Better!!!! When was the last time you changed your timing and balance belts and/or cam chain and tensioner? New Users please add your car's year and model to your signature line! Never break more than you fix! |
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10-30-2002, 02:58 PM
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thanks SoCalDriver, another question.
my tach is not working but the shift up indicator IS. I cannot find any loose grounds and want to avoid removing the dash to replace the tach if possible. could it be that the tach is not receiving the trigger signal from the coil? how can I check? thanks
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10-30-2002, 03:18 PM
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Does your car have the stock alarm or any other alarm?
If it does and has been disconnected there is a chance that the wire to the tach, which is used by some alarm systems, has been severed. To check the continuity of a wire you have to get at both ends of it. This means removing the instrument cluster. Not as difficult as it sounds especially for a post 85.5 car with the "newer" dash.
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Hugh - So Cal 83 944 Driver Person NOT a 'real' Porsche -- Its Better!!!! When was the last time you changed your timing and balance belts and/or cam chain and tensioner? New Users please add your car's year and model to your signature line! Never break more than you fix! |
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10-30-2002, 03:21 PM
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stock alarm...works fine. car is an 87na. FYI, the fuel guage also does not work...check resistance at the sending unit and appears ok. Don't know if they could be somehow related.
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10-30-2002, 03:33 PM
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Yes there is a "relationship" between the gauges.
There are flexable circuits that are used across the back of the instrument cluster. The instruments use various methods of attaching to the circuits. Could be a break or just a corroded contact. I would have to study the electrical diagrams and the instrument cluster for an 86 that I have from an 86 944 parts car.
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Hugh - So Cal 83 944 Driver Person NOT a 'real' Porsche -- Its Better!!!! When was the last time you changed your timing and balance belts and/or cam chain and tensioner? New Users please add your car's year and model to your signature line! Never break more than you fix! |
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10-30-2002, 03:47 PM
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thanks again, if you come across anything that will help give me another post. meanwhile i will take another look and perhaps take the instrument cluster off.
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87na guards red(mine) 98 suburban(mine) 04 4Runner(wife's) |
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10-30-2002, 03:55 PM
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If the tach just suddenly stopped my thinking would be a bad connection at the instrument panel. Start the engine and tap the top of the dash with your hand; this occaisionally makes the connection and the tach will work. My 944 was like that and we have had several other with the same problems. If the tach then works you need to pull the instruments out and clean/tighen the connections.
The upshift light will work with the tach not working.
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From November 2012; Precision Porsche Specialist Sussex UK, +44 (0)1825-721-205 2001-2012 Gerber Motorsport Inc. 206-352-6911 07.15.06 1996 Ducati 900SP. Suprisingly enough, it's red 08.16.09 1999 Kawasaki ZRX1100. Green. |
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10-30-2002, 04:05 PM
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Here's the back of the tach in the later instrument cluster. The brass threaded studs and nuts are what Britwrench mentioned.
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Hugh - So Cal 83 944 Driver Person NOT a 'real' Porsche -- Its Better!!!! When was the last time you changed your timing and balance belts and/or cam chain and tensioner? New Users please add your car's year and model to your signature line! Never break more than you fix! |
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10-30-2002, 04:39 PM
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nice pic! thanks guys....it's always nice to know you've got a couple of porsche gurus to give advice. I will check it out tomorrow!
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10-30-2002, 06:06 PM
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1983 Porsche 944 2.5 liter
