Good results, the P0171 code is normal as you are cutting fuel and so the lean code will activate......
I would suggest unplugging the PCU connector then using the Ohm setting check the harness for #1 injector for any stray ground, they should all be reading open. Then prove the circuit with the same setting (end to end), should show closed circuit (very little resistance)....
Just a thought, might you have pinched a harness when you reinstalled the intake manifold?.......Philip
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97, 4Dr, Controltrac, X engine, 360k
Ok Phil... Been searching high and low for the harness pinout diagram so when I do unplug the PCM I know which connection to test out. Found Ford V8 saying #58 for injector #1 but nothing on 4.0L V6? Any links... Anybody else know? I see this Noid tester but I would prefer to see volt reading as well as do the resistance check.
Thanks Phil... That as exactly what I was looking for! So in your first part I would be unplugging the harness and checking the hot feed while grounded to see if the line is grounded somewhere and in the second test I would be checking the injector hot wire on both ends for a break in the line somewhere... Correct? Lost sunlight here so I'll check in the AM. Thanks again!
Well finally got around to poking around the truck today. Threw a Noid light on injector 1s harness and with the car running it had the same flashing as injected 2. Side note... I gad to use the GEO Noid light as the Ford Noid light poles were way to wide. Also threw my meter on 1 and 2 injected harnesses and was receiving identical readings of what I think was 1.7 v with just the ignition turned to on without starting the truck. What should this reading have been? I thought it was supposed to be 12V with key on and the pulse of the break of the 12V was what triggered the injector to open or was I reading wrong? Was busy today but plan to spend more time with the truck tomorrow.
Ok... Unplugged the PCM and went from red wire on injector 1 harness to the corresponding hole (75) on PCM plug and got my meter to buzz showing no short. (+ to red wire and - to battery ground gave me a 12.4v reading as well.) How would I go about checking the ground wire for injector 1?
With the plug removed from the PCM you should have no power on the injector circuit. With no power your meter should not buzz..
Unplug the connector from the offending Injector.. and the connector from the PCM.
You should now have no Battery voltage on the circuits...
With the DVOM on the OHM setting
Connect one lead to the engine, touch each connector in the Injector harness, if you do not get a reading, there is no false ground..
using both DVOM probes, check for crossed circuits at the injector plug, One probe on a connector, the other probe to each of the other connectors individually, if you have an open reading on each wire, there are no shorts/crossed....
Using both probes, connect the DVOM to the Pin on the PCM plug(disconnected) and to the corresponding colour wire at the injector plug, you should read a closed circuit, if not the wire is broken...
.. Philip
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97, 4Dr, Controltrac, X engine, 360k
Try your steps when I get home and just to clarify the buzz was a continuity test on my meter... When I touch the + & - leads together it buzzes so when I touch the PCM plug at 75 and the red on the harness it is the same as touching the + to the - providing the is no break in the line. When I got the 12.x volt reading from + to red on connector and grounding the - on the battery was BEFORE I disconnected the PCM
Ok... Unplugged the PCM and went from red wire on injector 1 harness to the corresponding hole (75) on PCM plug and got my meter to buzz showing no short.
Since you were in the continuity test mode, technically your meter confirmed there IS a short between the two leads, which is what you wanted. If the wire were broken, there would be no buzz and you would have an "open" circuit.
Not sure if it is actually a "continuity mode". There is a setting that will make a buzz if you connect the + and - leads of the tester to eachother. I inserted a clip into hole 75 (injector 1) on the PCM harness plug and back probed the red wire on injector #1s plug and then touched the clip with + and the back probe with the - and got the buzzing. Doesn't that mean that the red wire from injector 1 to the PCM has NO break/short?
Another question for all to consider... Injector 2 on PCM diagram showed no color and is actually blacked out and on other diagrams I see of other systems have injectors 1&2 sharing the control wire. If that is true with my model.... Wouldn't 1&2 be acting exactly the same? Wouldn't #2 give me the rich error like #1 gives me?
Edit - looking into the hole on the PCM plug i can see 102 has no connector inside and the 104 pin diagram shows that as injector #2. The same diagram has white wire at hole 101 for injector #4 but I also see a white wire going into the back of injector #2s connection to injector. Tested the white on injector 2s harness and port 102 and my tester says it is the same wire. So now I am apprehensive at following this 104 pin diagram that tells me injector 4 is port 101 when port 101 is actually injector 2?
Not sure if it is actually a "continuity mode". There is a setting that will make a buzz if you connect the + and - leads of the tester to eachother. I inserted a clip into hole 75 (injector 1) on the PCM harness plug and back probed the red wire on injector #1s plug and then touched the clip with + and the back probe with the - and got the buzzing. Doesn't that mean that the red wire from injector 1 to the PCM has NO break/short?
Your test proves that you have continuity on that wire (which is good), but it does not test for any short...
Follow my test procedure, and read up on how to use a DVOM........Philip
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97, 4Dr, Controltrac, X engine, 360k
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