AMC Eagle Den Forum
The Mighty 258 => Engine Electrical Systems. => Topic started by: JMCwagon on March 16, 2021, 02:48:23 PM
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So, I can understand basic carbs and points all day, even understand modern systems for the most part, but I've been having trouble wrapping my head around the wiring of my 83 eagle. Im what you to call a young'un who discovered these gems, found a no-rust 83 in a field and pulled it out of the field, been getting the dents ( only 2) fixed and a paint job in the works, but literally every vacuum line and a bunch of wires were chewed by rats. I think my CEC system is fine and I could rebuild it fairly easily but I am wanting to do the ECM Test bypass I read about but only want to proceed if the Icu will maintain the ability to advance retard the timing based off of the knock sensor independent of the ECU.
Just for clarification I think a basic Carter bbd off non cec model and an air fuel ratio sensor in the exhaust is a much better way to go than CEC for me. Less to go wrong.
I have removed the ECU and entire CEC harness labeling all the connections and studied the wiring diagrams to a point, and from what I can see the knock sensor is included in the basic ignition and body harness instead of the CEC harness, I am just looking for confirmation if anyone knows for certain.
Thanks in advance!
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I can't find any knock sensor in any other diagrams except this 1988 one from the Eaglepedia: http://amceaglesden.com/guide/6_Cylinder_EEC_Module_Wiring_Schematic
Just for clarification:
Ignition Control Module=ICU, ICM (the box near the battery)
Engine Control Unit=ECU, EEC, MCU (the box under the dash)
This diagram shows the knock sensor running straight to the 'EEC,' though it also seems to have a 'CK' sensor next to it; this probably represents a crankshaft position sensor. I'm sure your 83 doesn't have one of those, my 84 doesn't. But I think it's fairly accurate because when I did my ECU delete, the only ICM wires left were coming to & from the distributor/ignition coil, and power/ground wires. There's just nowhere for a knock sensor wire to fit in at that point. I think the ICM would output an adjusted timing based on signals coming from the ECU, with the ECU looking at all the inputs (knock sensor, coolant temp, 02 sensor, etc) to make its decision on what timing should be. Since you have the whole harness out, you could follow the knock sensor wire to be sure.
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Yeah funny situation, I think I was confusing the oil pressure switch for a knock sensor :rotfl:. Apparently the knock sensor is the one red wire running to the top of the intake( I initially thought it was an intake air temperature sensor). I don't know why it's there but, I got that from the technical service manual I have for a jeep j10 which apparently is wired exactly the same.
I know they added the knock sensor in 83, if there was ever a crankshaft sensor I wonder when they added that.
And yeah, you're definitely right about all the timing changes coming from the ECM. Thanks I'm new, I didn't know we had all those wire diagrams here!
Is it weird that I wish ECM controled just timing but not fuel?
Anyways I'm going to pull the rest of the wiring harness for ease of access repairing rat damage and bypass the ECM for now just got to get 'er running.
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Yeah the Eaglepedia is a great source for information. Sometimes I just browse through there to see what it has to offer.
These CEC systems were kind of goofy, as most cars were in that era. They were just kind of added on to the existing systems to try and meet fuel economy and emissions standards. But that means it's not too hard to remove them, fortunately.
I did an ECU delete on mine, as well as a major vacuum line removal. I filled two grocery bags with all the stuff I took out. If you need any help on the specifics, don't hesitate to ask. We're one big happy AMC family here. :)