Crankshaft sensor
10-04-2012, 07:39 AM
#1
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Crankshaft sensor
I have recently replaced the crankshaft sensor in my S4 with a FAE 79208 but the engine doesn’t run as it is supposed to do. It starts OK, idle speed is too low, when driving on the road it hesitate to increase rpm but after some jerking with the accelerator pedal it catches up and runs OK at higher rpm but with a few misfires now and then and the fuel consumption is about 50% higher than normal at constant speed. It is not 100% shure that the problem is related to the sensor beacuse other repairs have been done simultaneously and this type of behaviour can also be caused by other flaws.
I hesitate to remove it without knowing for shure that the sensor is the problem, because there is so much to be disassembled in order to disconnect it.
TecDoc define that the Porsche 944 606 115 00 sensor can be replaced by a number of other sensors. Have anyone experienced problems after having replaced the OEM with something else?
I hesitate to remove it without knowing for shure that the sensor is the problem, because there is so much to be disassembled in order to disconnect it.
TecDoc define that the Porsche 944 606 115 00 sensor can be replaced by a number of other sensors. Have anyone experienced problems after having replaced the OEM with something else?
10-04-2012, 12:44 PM
#2
Three Wheelin'
Hejsan Herman..
Sure it's the CPS? Sounds like bad coil(s), coil connection or perhaps just corrosion at the coil wires.
The 944 CPS is just fine it just has a longer connection wire and costs less
Sure it's the CPS? Sounds like bad coil(s), coil connection or perhaps just corrosion at the coil wires.
The 944 CPS is just fine it just has a longer connection wire and costs less
10-04-2012, 02:26 PM
#3
Rennlist Member
+1 I think the problem lies elsewhere... may be a manifold airleak - suggest you check the idle vacuum at a fuel damper (the one at the front of the engine is easiest) you should get 21"Hg at idle speed.
10-04-2012, 02:32 PM
#4
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I'd start there.
10-04-2012, 02:58 PM
#5
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Use caution if it is dumping fuel running on half a bank you've got a good chance of the whole car going up in flame.
If you've got an oscope you can test the output of the cps at the CEL for peak to peak voltage.
If you've got an oscope you can test the output of the cps at the CEL for peak to peak voltage.
10-04-2012, 03:04 PM
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John Speake and 86_5Tiburon points in the same direction and an air leak downstream of the MAF might very well explain the problem. This could also explain why the engine runs better at high rpm. The air filter housing was removed during crank sensor replacement together with pressure dampers etc, which might have caused the sealing of the MAF vs the manifold to have been worsened.
10-04-2012, 03:13 PM
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The car is equipped with an ICC which prevents flooding with fuel. The signal from the crank sensor can be measured between P6 and P23 in the EZK connector in a S4/GT/GTS and I have oscilloscopes and will do, in case air leakage is not the problem. The signal shall be >=3VACpp when cranking.
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10-15-2012, 07:07 PM
#10
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Have you been running it with the screen removed ? It is repairable, send it to me and I'll supply an exchnage rebuilt unit by return.....
www.jdsporsche.com
www.jdsporsche.com
