Bad logic side of FICM?

6speedsd

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On an 03...

My old man was driving it the other day, said it started to miss. About like it dropped an injector. Said before he got it home, it was so bad it would barely pull up the driveway. I put AE on it Sunday, and it showed injector contributions for 5 and 7. It fired right up, missing on one cylinder. Did power balance, and although it wasn't a straight line, it wasn't dipping or spiking badly.
Started shutting down injectors one at a time...started with 7, no change which confirmed it wasn't firing. Went to 5, no change. Then all of a sudden, the longer it ran, the worse it got to where finally it wouldn't even idle. I could Rev it a little and keep it running long enough to shut down all 4 individually on the passengers side with no change (all the evens you could tell made a difference when disabled). Tore it apart today thinking bad harness. Every wire from the injector connector to the harness connector ohmed at like .3. Put it back on and in the process of taking the FICM off my truck to put on there and see how it acts. Voltage test at the pin on his showed 48v plus the whole process. Trying to rule out a bad logic side, as he had bad batteries a month or so ago. Just doesn't seem feasible that all 4 odd injectors would crap out once. When checking FICM voltage it fired right off, still sounding like a miss on one. So whatever is happening, as it runs and warms up is when injectors start dropping off. Anything I'm missing here? Will report back after trying my FICM.

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DEEZUZ

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Injectors are not split odd vs even, they are split up 2 on each side, 1,4,6,7 vs 2,3,5,8.

Any logic (12v) issues I usually find are the **** relay. No 12v in, no 48 out
 

6speedsd

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I was always under the impression they were. Anyways, when it got to its worst, evens would make a difference when disabled. I could tell no difference at all when odds were disabled.

Didn't look at icpv, but it built up to like 1200 icp when I was trying to refire it....it would hit and sputter but not actually run. Ipr was high.

Crappy part is I couldn't get it to retrip any contribution codes while it was missing so bad. I cleared them initially, let it run until it died, then rechecked and there was nothing. It ran probably 10 minutes or so.

It's not just a coincidence that all 4 on passengers side dropped off right?

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6speedsd

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The injectors themselves are still odds on passenger side and evens on drivers right? It's just broken down in the harness connector the way you listed.

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6speedsd

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Injectors are not split odd vs even, they are split up 2 on each side, 1,4,6,7 vs 2,3,5,8.

Any logic (12v) issues I usually find are the **** relay. No 12v in, no 48 out
His ficm showed 12 in, 48 out with a DVM.

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DEEZUZ

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But there should be 2 12v sources. Yes 1,3,5,7 passenger side
 

DEEZUZ

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Kinda sounds like air in the fuel, any recent work to pass bank?
 

6speedsd

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Not work at all.

Same issue with my ficm. First running, 1 and 7 don't show a change when disabled. The longer it runs, the worse they get. Now up to 1,3,5 and 7 making no change when disabled. BUT, I'm getting a cylinder contribution for #8!

Idling icpv around 1, icp 650ish, ipr 23.

With it idling on 4 cylinders, you hear the "knock" of working injectors on drivers side (2,4,6 and 8), but I here clicking on passengers side like it's just solenoids operating or something. All 8 buzz during a buzz test.

Scratching my head at this point. I just don't see 4 injectors dropping off and crapping out at the same time....that's a hell of a coincidence, especially all 4 on one side.

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6speedsd

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The part that's getting me is if you let the truck cool down completely, then crank it, it's only down on 1-2 cylinders, but as it warms up, that's when the other 2 drop off. It has to run 10 minutes or so before it gets that bad. In my head, and I could be wrong, but seems like that could possibly rule out a bad harness as well. I mean maybe it is injectors...they are all original on that side (260k). But if so, why would they fire/work when cold, but not when warm?

Did pull upper fuel filter. Didn't look bad at all. Cycled key and housing fills quick. Turned engine over with jumper wire and got no bubbles in housing either. I don't think it is any type of fuel issue, but just checking things off as they come to me.

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6speedsd

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Any other ideas? He's wanting to just throw new injectors in that side...I mean with 260k on them, he's on borrowed time as it is. But I'd hate for him to drop $800 on injectors and it not fix it. Part of me thinks that's the problem though...

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6.0 Tech

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Sounds to me like a loose injector, failed copper washer, or something of that sort, lime ctc said. Basically air/combustion gas in the fuel. Especially since one bank is dying. Could also be just fuel pressure, as 5 &7 are the last 2 to get fuel, then as moredemand on the pump and what not, starts not feeding that bank.
 

6speedsd

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I actually just hopped on here to ask about a failed copper washer. LOL

It always starts down one injector (#7). Also when it started this mess, I kept getting cyl contribution code for 7 as well. Maybe he lost the washer on 7, then domino effect back up the line? I guess I need to pull injectors on that side and have a look.

My test port fitting broke a while back and I forgot to order a new one, or else I would have already checked FP.


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6speedsd

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I pulled the upper filter earlier and cycled the engine over a bit with the jumper wire. If I had a blown washer, shouldn't I have gotten bubbles in the housing? Or would I need to spin it over for a while before that would happen?


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DEEZUZ

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Well you'd have to do it hot, when the issue is present. Remove filter, turn key to fill base, key off, then jump starter wire and look for bubbles. But yea this sounds exactly like air
 

DEEZUZ

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I've never had to. Always shows bubbles and smoke right through the tube
 

6speedsd

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It wasn't cold cold engine when I did it, but wasn't fully warm either. I'm going back out there tomorrow and pulling injectors to see what I find.


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