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Old 8th June 2009, 22:17   #1
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Default Cam Sensor-Crank Sensor-TDC Sensor. Are They The Same Thing?

In researching palio articles, (specifically older models like the 2002 el) the most frequent suggested answer to intermittent stalling/jerking problems seem to be
Have you checked the ___ (crank sensor/cam sensor/RPM sensor/TDC sensor) [fill in the blanks].

Are these the same thing?

To start off with the crank sensor is a black sensor which goes into a inlet below the engine and the top part is a wire which connects to a connector on the top of the engine block (close to where the oil dipstick is)

What are the others?
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Old 9th June 2009, 07:28   #2
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RPM sensor and the crank sensor are the same not just in Palio but in all cars.

Cam sensor and TDC sensor (if it exists) should be the same also.
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Old 11th June 2009, 14:08   #3
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Cam sensor and Crank sensor are not the same. The Cam sensor is mounted on the Cam shaft and Crank sensor on the crankshaft. Both are used to measure the engine rpm. Typically, the crank sensor is the primary sensor and the cam sensor is the back-up sensor.
Engine speed sensors (Crank & Cam) is one of the very few sensors which has a back-up sensor as engine speed is a critical element in deciding the functioning of the engine in the control algortihms.
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Old 12th June 2009, 00:03   #4
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I am not in a position to comment on other cars/engines, but on the Palio 1.6, the cam and crank sensors are not the same.

The first image (see below) shows the cam (phase) sensor. The second one is the crank (timing) sensor [Sorry for the poor quality pics]
Attached Thumbnails
Cam Sensor-Crank Sensor-TDC Sensor. Are They The Same Thing?-06112009.jpg  

Cam Sensor-Crank Sensor-TDC Sensor. Are They The Same Thing?-06112009001.jpg  


Last edited by vipul_singh : 12th June 2009 at 00:04.
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Old 12th June 2009, 10:52   #5
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Quote:
Originally Posted by vipul_singh View Post
I am not in a position to comment on other cars/engines, but on the Palio 1.6, the cam and crank sensors are not the same.

The first image (see below) shows the cam (phase) sensor. The second one is the crank (timing) sensor [Sorry for the poor quality pics]
Thanks vipul. That makes sense.

To complete the picture, where does the infamous lamda sensor fit into this picture?
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Old 12th June 2009, 20:44   #6
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Lambda sensor is the oxygen sensor. It's fitted into your exhaust.

Cheers
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Old 5th October 2009, 09:41   #7
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What could be the possible cost of replacement of Crank Sensors?
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Old 5th October 2009, 10:59   #8
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Quote:
Originally Posted by karizma_devil View Post
What could be the possible cost of replacement of Crank Sensors?
1500 rs odd. But reading your issues on the other thread, i would keep an eye out before rushing to replacing it.

Symptoms will be car cutting out while driving. First at low speeds then at medium speeds. Just before it cuts out it will feel as if it is gasping for breath.Once it cuts out, it refuses to start. Then will start after 10 mins, 20 mins and then maybe after 40 mins.
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Old 5th October 2009, 11:17   #9
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just a little input on these sensors:
crank sensor works on electromagnetic induction and cam sensor works on hall effect principle.
the crankshaft has a thin disk usually bolted or welded onto it which has teeth machined on the periphery like shown in the drawing. because of this, the sensor will pick up a pulse. now, there is one missing tooth on the wheel so when this comes face to face with the sensor, there wont be a pulse. so the ECU can understand two things from this:
1. what is the frequency of this missing pulse; implying RPM of the engine and
2. TDC of first piston or whichever you tell because the disk is bolted to the crank.

now, knowing when TDC is coming, there is a problem because during a complete four stroke cycle, TDC and BDC are reached twice, once at the end of exhaust and other at beginning of power stroke. for this purpose, there is a cam sensor and hence also referrd to as cam phase sensor.
two piston TDCs but there is only one rotation of camshaft. so at both tdcs, camshaft is 180 degrees opposite.
cam phase sensor has four lobes or something like that. knowing the position of the camshaft, the ecu can tell which TDC is the first piston is at.
for every other cylinder, there is a delay corresponding to the firing sequence.

hope this helps.

lambda sensor generates voltage when it is exposed to excess oxygen in the exhaust. you can have two lambda sensors, one in intake and other in exhaust, the first one being used for reference.
so, lesser the oxygen, lesser is the voltage accross the sensor. this is used as a feedback to the ECU for injecting the correct fuel quantity.

please let me know if you guys want to know anything specific. i might be able to help.

cheers
nitro
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