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Discussion Starter · #1 ·
1995 engine, my issues is with 6&8 injector not firing. I replaced the pigtail and harness same issue but now oil was squirting from the return under the solenoids. Ran tests, solenoids good, wiring good. That tells me it’s a fuel issue. Threw 2 known good injectors in and same issue. Threw 2 brand new injectors in same issue. Compression test good. Within +-5 psi of all other cylinders. Really stumped with this one. Any help would be greatly appreciated.
 

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How does it run? Just curious about 6&8 not firing is it because, those are the codes you are getting? Do you have a chip? The reason I am asking is because, my truck was running great but, when I would hook up the scanner it would show those same 2 injector codes all the time but, when I removed the chip the codes went away.
 

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Discussion Starter · #3 ·
It starts good and runs but with a noticeable miss. I’m not throwing any codes, I do Not have a chip. I can Unplug the harness to the two and the solenoids will stop clicking and the oil flow will stop but there is NO change to the idle. Plug it back in oil flow returns. Unplug the harness to 2&4 and the truck will run extremely rough for a few seconds before dying.(does the same with 1&3 then 5&7 as well) so my issues is ONLY with 6&8. Ive heard of an IDM failure causing a whole side to cut out, but not just a pair.
 

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Sorry, not much help then that was the second time I had a problem with 2 injectors at the same time one was caused by the chip and the other was caused by the harness. Hopefully, others more experienced will chime in. Good Luck! and keep us updated as to the fix.
 

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Are you using a power stroke capable scanner not all scanners can read these trucks especially, cheaper ones. Can you do an injector buzz test that would reveal all injector codes. I would believe, that if you are having injector problems there would be stored codes. Just thinking out loud.
 

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Discussion Starter · #8 ·
Used a Snap-on Modis Ultra. Passed the buzz test with no codes. On the cylinder contribution test 6 and 8 changed the idle none. P0278 (cylinder 6 contribution/balance fault) and P0284 (cylinder 8 contribution/balance fault). Only other codes present P0107 (map sensor low input-I had accidentally unplugged it) P0113 (IAT circuit high input) and P1705 (Not in park or N with KOEO/KOER) but I know Those would not contribute to the issue I’m having.
 

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Damn, I was really hoping you were using a cheap scanner and just couldn't retrieve the codes. Lol I believe on our trucks both the PCM & IDM in conjunction are utilized in the operation of these engines. Usually when an IDM fails the vehicle will not start which yours still does. I have only had to replace 1 IDM and 1 ECM in the 15 yrs. and 1 million miles on my truck. When IDM failed mine would not start it's been so, long ago when the ECM failed I don't remember what was wrong. Do you have a spare ECM that you can try? Hopefully, someone else has suggestions because, i'm not sure what else to try.
 

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Discussion Starter · #10 ·
Haha right? I wish It were like that too! Haha that’s pretty awesome you have that many miles! I have An identical 1995 to swap parts from, only difference on the good truck it’s a 2wd dually. Both 350’s though, so I wouldnt See why I couldnt Swap the ecm just to see what happens. I’m just lost as to how it’s just those 2 cylinders, it all pointed to bad fuel side of the injector but after I threw 2 brand new ones on it makes me thing wiring, HOWEVER if the wiring were to be bad how would it pass all the tests? It’s a 7.3, how hard could it be? Lol
 

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Discussion Starter · #11 ·
Important side note, so I’ve had the truck for a couple years and I originally Got it for just a personal build but it had this miss, I just Started parts changing with the harness and such and just didn’t have time for it since I was Working out of town So I sent it to my buddies shop thinking it was just a couple injectors and he said he thought my cylinders were bad since the injectors passed all the tests. So not even thinking I went out and grabbed another good used reman 7.3 long block. Threw all my parts into the same exact locations and when I put The engine back into the truck I had The exact same issue from the same cylinders. That’s the reason I just decided to throw the Injectors at it but same issue. That’s when I did what I should Have from the start and went through the diagnostic tree. So basically the only things I have Not changed in that system now are the ECM and the ENTIRE engine harness. I ruled Out a blockage in the head and ANY cylinder issues after the whole pointless engine swap. That is what lead me back to the forums of infinite wisdom where I lived In highschool where a man with the tag of Chuckster always had the correct answer to literally every question I had haha. I guess Now I’ll just wait for the missing link of information to come along.
 

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I believe it only matters if one is automatic and the other is a manual or if they are from differing PCM families but, not 100% sure. Once you pull out the PCM's you can check the numbers on them. Maybe the only thing that might not work is the 4x4 light on the dash but, I don't know for sure. Yeah, not sure why it would pass all the tests and I have learned sometimes these trucks can be hard to figure out if you don't have all the right equipment and knowledge. Lol
 

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Important side note, so I’ve had the truck for a couple years and I originally Got it for just a personal build but it had this miss, I just Started parts changing with the harness and such and just didn’t have time for it since I was Working out of town So I sent it to my buddies shop thinking it was just a couple injectors and he said he thought my cylinders were bad since the injectors passed all the tests. So not even thinking I went out and grabbed another good used reman 7.3 long block. Threw all my parts into the same exact locations and when I put The engine back into the truck I had The exact same issue from the same cylinders. That’s the reason I just decided to throw the Injectors at it but same issue. That’s when I did what I should Have from the start and went through the diagnostic tree. So basically the only things I have Not changed in that system now are the ECM and the ENTIRE engine harness. I ruled Out a blockage in the head and ANY cylinder issues after the whole pointless engine swap. That is what lead me back to the forums of infinite wisdom where I lived In highschool where a man with the tag of Chuckster always had the correct answer to literally every question I had haha. I guess Now I’ll just wait for the missing link of information to come along.
I did have to replace my engine harness once do to a driveability issue. Luckily I had a brand new engine harness on my spare motor. If you decide to swap the harness and the ECM do them one at a time so, that way you know which one fixed the problem if it does which I hope one of them does.
 
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