#7 injector issues plz help diagnose

[m j]

did a long trip this Canada Day weekend.
went from Vancouver BC to Grande Praire AB to Fort St John BC and home.
truck started acting up after Grande Praire. first symptom was laboured starting.
after loading a car on the trailer in FSJ I fueled and grabbed breakfast and coffee at Tim Hortons and went to pull on to the highway.
CEL and motor starts chugging badly.

so on the side of the road I start trying to troubleshoot.
Torque app says "no codes stored"
oil level is good and clean (changed 2 days before trip with T6 synthetic and a donaldson elf7405 huge filter)
fuel in the bowl, filter fresh as well
if I unplug the left rear valve cover connector it runs better and CEL is off

so I pull the valve cover to inspect the UVCH. it looks perfect and DVOM says its good but I failed to check for continuity between the injector pins
injectors 3.5ohms
nothing looked 'bad' under the covers so I buttoned them back up.

I pulled the pins from the harness connector and tried disabling 5 and 7 seperately.
5 disabled 7 connected motor ran rough like on six cylinders, 5 connected 7 disabled it smoothed out on seven cylinders, bothe 5 and 7 connected CEL and rough running

at that point 1300km from home and having to be at work I pulled 7 from connector and hit the highway on 7 cylinders

missed work on Tuesday and worked today.

to me it feels like 7 is trying to fire out of time.
having 7 connected the starter works very hard to spin the motor.
I guess I have to try a few more continuity tests at the valvecover connector but everything there 'looks ok'
so I guess the next place to look at wiring is back at the engine harness plug on the driver side?
do injectors die like that? is it electrical?

any help is appreciated

Thanks
Michael

 

[ghohouston]

Pull valve cover, take the ohm meter to where the engine harness plugs into it with one lead, then take the other lead to each injector plug, and then the glowplug plugs. But yes, an injector can just go bad like that, snd it doesnt have to be electrical, it could just be worn out

 

[m j]

I found this test chart online and am going to do them now...

 

[m j]

left bank were all between 3.5-3.8ohms
right bank with the problem injector are 3.3ohms

I have to figure out a way to test if 7 is getting a signal from another injector...continuity from the other seven pins I guess?

 

[ghohouston]

youre over thinking this. if you checked resistance individually, and all checked out, then 99 percent of the time, your injector is bad. 7.3's arent too bad about dropping injectors, but it does happen, more often that most people lead you to believe about them... it would be best to get someone with a scanner to take a look at the truck, run a injector buzz test, if it buzzes, and you said every injector connector passed resistance wise, then you are pretty much guaranteed it is the injector. also, if you find someone with a good scanner, get them to run a cylinder contribution test

 

[m j]

trust me, I want it to be a dead injector so that I can justify the cost of FullForce 300/200% injectors from Irate
but if I buy them, and the same issue is still there, I will have some explaining to do

 

[ghohouston]

I understand. Hell, if you cant find access to a scanner, although I highly suggest it, you can always use the failsafe method of swapping two injectors around, and see if the problem moves holes or stays with the same cylinder. Its EASY to swap around 2 injectors on a 7.3, and if the motor isnt burning hot, shouldn't take you 30-45 minutes from teardown to having the truck running again

 

[ActionRick]

1 bad injector solenoid will shut down the entire bank . IDM goes into limp .

 

[m j]

pulled #7 and #3 do do a swap to check if issue followed injector...orings on #7 are washed so it looks like HPO was pushing in to the fuel side



local International dealer is open today so I grabbed two oring kits 1833564C92 for $46
#3 had some gunk on the body

 

[ghohouston]

Was your old fuel filter black/ dark colored? And did you get it back together and see what happened yet?

 

[m j]

runs better.
lots of white smoke and long cranks to fire. assuming/hoping its just air in HPO system
do i let it work itself out or am I supposed to try and bleed it?
I have a HPOP test gauge I made up but havent used so maybe I will install it and see if I can fill the HPO rail??

 

[ghohouston]

Go drive the piss out of it, its really the best way. If you feel the need to, but not all a necessity, you can pull a plug in the oil rail and add oil, but will be messy on the odd side bank, so I would just go drive it hard. Do w.o t. Runs

 

[m j]

$57 on ebay for 8 o ring kits to my door in Canada, much better then local pricing at over $160.

just pulled the FPR to clean the crud off the screen, plenty black and disgusting, I would say oil was present.

so if I do injector o rings I can probably hold off on injectors, and get my s468 turbo and intercooler and zf5 rebuilt as per the original plan, with injectors after the rest is in place.

thanks for the help
Michael

 

[neverkickn]

$57 on ebay for 8 o ring kits to my door in Canada, much better then local pricing at over $160.

just pulled the FPR to clean the crud off the screen, plenty black and disgusting, I would say oil was present.

so if I do injector o rings I can probably hold off on injectors, and get my s468 turbo and intercooler and zf5 rebuilt as per the original plan, with injectors after the rest is in place.

thanks for the help
Michael

I would run it for a couple of days to make sure that the orings fixed your issue first. If so then maybe do new rings on the other injectors that you haven't touched. If you drain the oil rails and suction out the cylinders it will greatly reduce the amount of smoke after a injector r&r. It may not matter to you but it always freaks me out when I have to run it for a solid day or two to burn all the oil out of the manifolds and muffler.

1 bad injector solenoid will shut down the entire bank . IDM goes into limp .

Are you sure?

 

[m j]

I did drain the oil rails, through the 2 small plugs under the valve cover.
didnt drain the fuel rails. turned over the motor with 15/16 socket on the crank pulley to paint my AC box with oil/fuel squirting out the glowplug openings

 

[ghohouston]

Best way to evacuate cylinders is pull glow plugs, set valve covers back on, with both injector harnesses unplugged, and glow plugs out of each hole an injector was removed from, go turn the key over 5 or 6 revolutions, put all back together and youre good

 

[ActionRick]

Quote:
Originally Posted by ActionRick View Post
1 bad injector solenoid will shut down the entire bank . IDM goes into limp .
Are you sure?

Yes Very sure . O rings won't set a Cel either ...

 

[neverkickn]

Yes Very sure . O rings won't set a Cel either ...

Yes they will. ICP lower than desired.

 

[ActionRick]

Yes they will. ICP lower than desired.

OK , this one was on and off , so I guess the O ring got better & worse by unplugging the wires ...

Since you just want me to be wrong ,I'll stop trying to help ...

 

[neverkickn]

OK , this one was on and off , so I guess the O ring got better & worse by unplugging the wires ...

Since you just want me to be wrong ,I'll stop trying to help ...

I never said or implied that I wanted you to be wrong just for the sake of proving someone wrong. This is a tech thread, check your feelings at the door. I just don't see a bad solenoid causing a code and ohming fine at the same time. It works or it doesn't. He said the circuit ohmed good so why would you rule out an injector malfunction.