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John Vieira
John Vieira, Ford Mechanic
Category: Ford
Satisfied Customers: 76
Experience:  ASE Certified Technician 32 years with Ford specializing in drivability and electrical and AC. Ford certs and ASE Certs
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Customer Question

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JA: Thanks. Can you give me any more details about your issue?
Customer: Yes, injector issues on a 2002 ford F250 XL 7.3
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Submitted: 1 year ago.
Category: Ford
Customer: replied 1 year ago.
The engine has miss, cleans up a little after warming up but can still hear it in the exhaust, Diagnostic program keeps showing up as cyl1 high to low fault, But i have ohmed from the DIM all the way back to the DIM and showing 3.9 ohms all injectors. Also energized injector using 12V through wiring as a stress test and clicks well. Have changed UVC gaskets and harnesses and several rebuilt injectors, Hell i have moved them around so many times i lost track of one of them, i just know a new one is in Cylinder #2 but i also THINK one is in cylinder #1. I have ran buzz tests and KOEO & contribution tests sooooo many times and cleared codes as well. Not sure if the code clearing thing is really making it to the IDM though, cause these could be old codes. i cant see anything for BARO so i opened PCM and see no BARO, doesnt have a external one either so i think maybe it a fixed programmed number. Cleaned all the pins on both IDM, 42 Pin, external harness UVC connector, Pcm & connector. Checked compression all cylinders at 300 Psi, (400,000 miles) I have cleaned the IP control, changed oil by empting the reservoir running a quart of oil thru it then draining it again along with crankcase then fill filter install and top off with oil. removed fuel tank cleaned out the tank installed a damaged foot screen and cleaned both filters in level indicator assembly, changed fuel filter and cleaned out base of filter holder. I am going to try to snapshot some of my diagnostic readings and attach, probably have to send a word doc to get them attached. Also when i WOT engine (scary cause sound like it going to blow up) The engine starts surging and freaking out at WOT. I checked fuel psi at idle to be 57 PSI but not did not check at WOT.
Expert:  John Vieira replied 1 year ago.
Have you checked the IDM voltage? If it's below 40 Volts- it's an issue. You should be able to monitor that with your diag./scan tool.It sounds like you have been through everything already, except for replacing the IDM. That would be my recommendation. It is very much normal for the engine to surge and miss and freak out and miss when you run it at high idle, no worries there. That is the perfect characteristics of those engines. I am happy to follow up with any more questions regarding this issue or any other issue you may experience. You are so well prepared to handle this, very nice. Thanks.Sincerely,John Vieira
Customer: replied 1 year ago.
I don't have it available in ForScan it a beta free copy, unfortunately. Is the 40 volts AC current? Can I back probe a connector? Is it as easy as placing voltmeter on AC and placing negative probe on body or engine ground and positive probe into injector signal wire? I would think I need to crank engine and start right? I have access to all data online manual but it doesn't detail much about testing IDM output. I forgot to mention all but 2 injectors are AD but someone put in a #6 AB and #8 LL AB injectors. This a 49 state emissions can this cause additional issues as well?
Expert:  John Vieira replied 1 year ago.
I know that the 7.3 require 1-7 is one part number and #8 is a different part number. If you have any discrepancies with the part number on 1-7 they should not be that way. They need to all be the same part numbers.You would do well if you check and see what color your CAM sensor is. If it is anything other than gray, then replace it. Because they did have a recall on those sensors and they went to gray sensors. 40 volts should be DC currentNo, you can not back probe a connector.You are right, needs to be to check it.On the 6.0 engines, they have a provision for checking the voltage through the access plate on the IDM module. I am searching my memory, if that is the case with the 7.3's. I don't think you can...Anyway get back to me with your progress. I am here if you need me. ThanksSincerely,John Vieira
Customer: replied 1 year ago.
I pulled the harness IDM connector apart to back probe, started engine & I tried to find 40 volts DC or AC on the outputs of the IDM but was not successful. Using oscilloscope AC coupled was able to view a 100 volt square wave with a over layer > 400 volt spike (I thought maybe spike is coil magnetic field collapsing ) I attached image. The scope connection was the high side to the low side of #1. I probed same connection with voltmeter, I attached that video as well. I viewed the Fuel delivery command signal & CID signal by placing negative of scope to Pin 2 signal return and probing the other signals and i found smooth signals (Other then a slight expansion periodically when engine slightly surge) I watched all injectors outputs and they where all the same very consistent. I ordered a IDM should be here Sunday at noon, But i am very unsure if this is the right thing to do! !!!!!! To get it i have to give mine up as a core so there no turning back, I know they do warranty but i do not believe they do returns. So if it not the IDM then i just wasting money that can go towards more injectors.
I found that the Baro is mounted in the IDM not the PCM, I see no signal pins on output of IDM for the BARO i have no idea if it works or not, With Forscan it might be possible that i cant see it because I can not look directly into the IDM only the PCM.
I sent you several videos please watch them and listen closely to the miss and the heavy diesel knock. Let me know what you think about all of the above.
Just in case the sounds "sound" normal (As so many people have mentioned) 3 of these trucks where purchased and maintained by the same company i have 1 and my brother in law and father in law have the other 2 and i have listened to all 3 parked side by side, mine is definitely different. I tried for over a 2 hours to upload a 1 minute video with sound and failed. You might play Volt INj8 really loud and here it otherwise i try in the morning to make just a sound recording and send it.

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