Fuel Composition Sensor (FCS)
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Joined: Jun 2009
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From: colorado Springs
Fuel Composition Sensor (FCS) Donor rig is an 03 Tahoe with Flex Fuel capability, and I'd like to retain that if possible. So here goes:
I received the FCS when I got my engine, harness, and PCM but it was only connected via the harness. Which tube is the inlet?
I've had the rear O2 sensors deleted from my PCM, do I need to use the After-Cat O2 sensors when running E85?
I received the FCS when I got my engine, harness, and PCM but it was only connected via the harness. Which tube is the inlet?
I've had the rear O2 sensors deleted from my PCM, do I need to use the After-Cat O2 sensors when running E85?
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On The Tree
Joined: Jun 2009
Posts: 194
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From: colorado Springs
I just Googled this topic and it seems that either fitting can be used as the feed and the return. This is because the sensor is able to determine what kind of fuel is passing thru. I'm assuming that GM had some extra fittings in place on the donor vehicle that would've come in hand for the swap if you wanted a factory looking install.
Joined: Sep 2004
Posts: 3,148
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From: Downers Grove, IL
The sensor is hooked up from GM so that the nipple closest to the electrical connection goes to the fuel pump. The further smaller diameter connection is connected to the fuel rail.
Joined: Sep 2004
Posts: 3,148
Likes: 12
From: Downers Grove, IL
Depends on what PCM you have. If you have the blue/red PCM you cant do it. If you have the newer green/blue PCM you can probably add a FCS and reflash with a flex fuel tune. The easiest way to do it is to just start out with a flex fuel motor.
I just did a swap on a 77 c10 and the engine was out of an 03 tahoe with the red and blue pcm and had the flex fuel system. I had the flex fuel tune removed and also trashed the fcs.
