[Jaydon]

I bought the truck 4 years ago with 240k on it. Didn’t have any history on it prior to purchase. Had a good friend at a diesel shop run some checks on it before I bought it. Compression was good on all 8 (380 psi or better) along with no codes and good fuel pressure (50ish psi) under hard load. All was good so I bought it. Right away I replaced many wear parts and did common upgrades to prolong reliability and performance. Hutch/harpoon mod done etc. not gonna list everything


Truck ran good and worked hard up until I put a hydra tuner on it 2 years ago as I wanted more power and firmer shifting for towing. Was all good for 6 months with the tuner until I burnt up the trans, bought a core to rebuild and swapped bad one out which went good. Problems with engine performance surfaced also such as low power on accel ,high fuel consumption, miss at idle, long crank when hot . Wanted to fix myself so bought forscan and torque apps to run tests and monitor. Cct failed cyl 8 with (7-8%) a few times (cps is the ford dark grey with purple) any way... everything else checks out
icp 500psi idle / 2800-3100 psi hard accel.
Ipr duty cycle is 9-11% @ idle and never above 55% under load with tune.
Fuel pressure (via mechanical gauge) 70-75psi @ idle and have seen it go down to near 40 psi when really mashing pedal.
Passed Buzz test all injectors sound good cold.
Cct showed cylinders 1-7 @ less than .75% during idle warm engine, cylinder 8 failed with 7-8 % on several occasions.
Cleaned ebp tube (is new and wasn’t obstructed)
No visible up pipe leaks as they look fairly new and are the bellowed newer version
No boost leaks (made leak tester).
No oil leaks anywhere other than some oil inside intake plumbing. I addressed this with oil catch can routed back to intake.
I replaced lpop with updated mahl pump as old one was leaking oil awhile back....lpop output is good.
Pulled valve covers over a year ago to look at injector spouts while running... they all were spurting the same amount. Injectors looked recently replaced also.
Truck still has same symptoms that started over a year ago. Not sure where to look next ...any input is appreciated. Thanks

 

[guitarnut]

Cct on #8 always fails.

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[Jaydon]

Your right #8 does usually fail but not with 7-8% .
What I here and see when #8 fails cct it’s not that high. But I may be wrong and barking up the wrong tree.....

 

[guitarnut]

Your right #8 does usually fail but not with 7-8% .
What I here and see when #8 fails cct it’s not that high. But I may be wrong and barking up the wrong tree.....

So to be clear, low power is the problem?

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[Jaydon]

So to be clear, low power is the problem?

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Yes. Power feels down and has been for awhile. The miss is definitely getting worse also, does smooth out beyond 1500 rpm.

 

[Jaydon]

No 7.3 gods out there?

 

[guitarnut]

No 7.3 gods out there?

Plenty. Maybe it'll take a couple of days. I'd go ahead and monitor and record all the vital signs like hpop, IPR, map, etc. Record it And see if you can find a time when they are not right. Eventually one of the experts will see your thread. Forum has been slower than normal past couple of weeks.

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[Jaydon]

Thanks again for your replies. I have been monitoring and will continue to. 👍

 

[guitarnut]

Thanks again for your replies. I have been monitoring and will continue to.

Consider posting them. Maybe that will help someone chime in.

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[Jaydon]

Update: found more time to work on my truck.
With the truck still running with same symptoms listed in previous post plus Perdels still showing 8ish on cylinder 8 and code p0284. I bought a set of used injectors to rebuild and replace my current ones and also ordered a test kit with the glow plug adapter to check compression. Anyway , took d.s v.c. off to observe injector spouts and unplug injectors to listen for change while running...2,4 and 8 all splashed the same but 6 was puking about half the rate of others and engine responded greatly when I’d unplug each injector even 8. Starting thinking injectors are probably just worn out or orings bad. I than swapped out inj 8 with one I rebuilt, observed the old # 8 inj and lower o-ring looked chewed up on one side. Fired truck up with the swapped #8 in and let it run for 20-30 min periodically reving engine getting it up to op. Temp. Ran worse and Perdel now showing 11ish on cyl. 8....wtf . Thought maybe with 6 spurting weak it might’ve been the contributing problem on 8 so I swapped out 6.
I now get codes p1276 and p1278 on buzz test , still p0284 on cct and runs like trash. Drove the truck 250 miles since 6 and 8 swap ...problems haven’t cleared up. uvhc harness felt tight and looked replaced recently still cleaned them and applied dielectric grease on connections. Never got to do compression because the adapter was to close to rocker arm. Not saying my injector rebuilding was or wasn’t a success but my diagnosing knowledge isn’t going well either. Ready to light the truck on fire. Anyone with advice other than compression test (waiting for adapter) please chime in. Thanks

 

[Hydro]

What do you mean by rebuild?

injectors with a lot of miles on them will have worn armatures and limit how much oil is spurted out of the spouts
not much oil = not much fuel out the tip
a shim kit may help or replace

common for number 8 to show issues in a cylinder test, just the way the system works
some engines used a different injector in that position

Are you confident about the electrical connections to the injectors?
disconnecting one at a time is a good way to evaluate the injector contribution, providing base compression id good on each cylinder

 

[Jaydon]

Rebuild as in cleaned nozzles and parts in ultra-sonic cleaner, new orings and shim kit getting all armature plates at .04 gap.
Rebuilt AE injector in the 8 hole and AD in the 6 hole... I do have 6 more rebuilt AD injectors. Maybe I’ll swap 6 again....
Connections were all tight and clean upon disassemble and same when assembled.
I’m pretty confident that all connections were good. I even retorqued the inj. Hold down bolts and checked all rocker arm bolts on that side.. I opened a can of worms here!! I do have a pair of new uvch s I bought for safe measure awhile back just haven’t had good enough weather to further work on truck. Icp and ipr values are in spec.
All injectors sound the same in buzz test several times .

 

[Hydro]

Did you check the intensifier piston return springs
and nozzle pintle clearance?
that lazy number 6 concerns me
maybe swap it out to a different hole and see if it acts the same

 

[Jaydon]

all springs were replaced with new ones in each inj I did. I did not check nozzle pintle clearance ..just visually inspected them for wear. I plan on swapping out 6, maybe something up with connection on injector or injector is garb.

 

[Hydro]

if you put in new tips, then checking clearance is not necessary, just old tips can get worn and affect the flow rate
the pintle seat wears and the pintle to stop plate will wear making the lift too high
tips are not all that expensive, if you go to all the trouble to go thru an injector, the tip would be replaced in my opinion

can I assume new o-rings inside the injector?

several electrical connections between the injector coil and the IDM to cause problems, check the terminals for spreading or burning

 

[Jaydon]

Yes new inside oring, -30 windchill this morning... If it ever warms up some I plan on going thru connections with a meter from idm to inj.
What is confusing is the way buzz test sounded every time on all injectors, evenly sounding and well pronounced. I suppose with engine running it’s a different story because of vibration etc.
Back when after I changed the 2 injectors I do recall twice reading perdels where cylinder 8 was cutting in and out (reading 11 than 0 than 11) at idle. 💡 ...now I must ohm out connectors and wires.

 

[Hydro]

3 o-rings inside a 7.3 injector
checking straight from the IDM would give a better analysis of the harness as a whole, since you would not be disturbing the intermediate connectors
really, the buzz test and listning to the injectors should tell you if the wiring is good -- if they click strong, then the connection is good

normal for #8 to sometimes fail CC test -- that injector has a different coil than the others -- also depends on the testing tool

14F here this morning, dunno about wind chill, fed the cattle yesterday so only a short run to check for new calves today

 

[Jaydon]

14f Is still cold, I’m waiting for at least mid 20s to attempt any more work on truck .
Yeah all orings were replaced with ones from riffraff. I got curious and tore apart the number eight injector that I removed back when this mess all started..And kid you not all parts out of the injector looked better than any of the eight used ones that I bought to rebuild. Poppet valve and seat were in excellent shape/no wear at all same as plunger and barrel. Checked arm. Plate it was .003 and nozzle jets were all open spraying brakeclean through all 5 jets. I’m actually pissed I removed it in the first place . Yes the lower oring had some gouges but i doubt it was the problem.
I will update with my findings with the electrical between idm and square main harness, going to just replace the uvhcs. Thanks Hydro for your input.👍