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Bad Injector?

Will L. said:
Am I misunderstanding, cracking the injector line nut? Opening the line feeding into the injector and getting different results doesn't show a problem with the injector, it would be a restricted line or ip.
If you do suspect an injector, swap it with it another and see if the problem follows it. If just one is bad try disassembling and cleaning it.
Click to expand...

I would try this first, would eliminate a few things. IF the miss follows the injector, then bad injector, if it stays, then IP or cylinder issue.
 
turbovanman said:
I would try this first, would eliminate a few things. IF the miss follows the injector, then bad injector, if it stays, then IP or cylinder issue.
Click to expand...

Or injector line. Rare but it happens. undo 2 lines and run pumping fuel into containers for comparisons. if 1 line bad remove line in question and ensure it is clear.
 
Thanks for all the advice and help guys.

Yes when I cracked the nut on the fuel at the injector I got different results between the # 3 and # 5 cylinders. Maybe it is a plugged, I checked them when I was putting her together. The odd thing is the rattle/ knock is almost completely gone now. Before I take half the truck apart I think I will clear the code and swap injectors to see if it follows the injector.

Now you guys school me on the scantech software. My only diagnostic tool to this point has been a paper clip.:D What purpose does shutting one injector down serve? When I cut them off using the software the truck stumbled and ran rough with the injector off. It did not matter if it was #1 cylinder or #7 cylinder. I believe if I tried to cut 2 off at a time she would die. Now when I cracked the nut at the injector the effect did not seem as dramatic. What else can one do with this software?
 
The software can instantly and easy to shut off a cylinder. You do one at a time and should have exactly same result with all cylinders. Lets say for instance a 200 rpm drop. If 7 are the same but 1 only drops 50 rpm, that cylinder is not getting proper power you have to chase it from there. The software lets you do all 8 quickly and clean.

if you find a difference and you see what you are describing with 1 having different fuel flow, the next step would be undo the lines from the injectors, bend slightly to fit in a container and measure volume output. Hopefully it's the same and you just had one line looser than the other or something like that.
If volume is same, pull those 2 injectors and swap -don't try cleaning yet ID the problem first.
 
Thanks Will L. Next time I get a chance I will shut them off and see what I get. I am definitely going to swap the 3 & 5 injectors. Will keep you guys posted.
 
Update. Well its not the injector nor is it the pump. Hooked the software up and shut the injectors off one at a time and they all dropped evenly in rpms. I pulled the #5 injector and replaced with a new Indian injector I had laying around. Still made the noise on subsequent test drive. So I shut the #5 injector completely off. Viola, after a short test drive the noise is gone. So now I know it is mechanical. So I take the valve cover off to inspect the valvetrain and everything looks great. So now I know I have a bad hole. Kinda bummed, not sure what it is. Idles great without any noise. Pistons looked fine when I inspected and cleaned them. Do not want to pull the motor... Any thoughts? What would only make noise on acceleration and under load but not at cruise and idle. Stumped at this point.
 
Can it be piston slap? If piston is in backwards, but I think you would have valve train damage if it was?
 
Burning oil said:
Can it be piston slap? If piston is in backwards, but I think you would have valve train damage if it was?
Click to expand...

I can check my pics but I almost 100% certain I put the pistons back in correctly. I am stumped partially because at idle she sounds fine and at 60 and steady cruise on flat ground she sounds fine. She has made the noise from day one-as soon as she fired and I drove her she has made the noise.

Oil pressure is great. No vibrations and it feels strong power wise-it will bark a tire. I have not really got in her to hard with this noise. Builds boost-have seen almost 15psi. The only symptoms are she smokes white or grey on moderate acceleration and blue grey going down the road. The smoking seems to be getting worse not better. I do not drive the truck-have put maybe 150 miles on her since putting the motor in.
 
Well an update. I had to order a compression tester and fitting. Finally got that stuff sorted and had a chance to check the compression. At first I thought the gauge or the operator was defective because I was not getting a reading on the #5. So I check the #3 cylinder and after a few cranks she goes up to 400psi and holds. I check the #1 and the same right at 400psi. I know now I have a completely dead hole. Not sure what happened this go round. I guess I am looking at pulling the motor....

She gets one more chance at life and then I swear I am finding a big cliff to shove this thing off of!
 
I bet you have a valve not seating. Put that cylinder at TDC and put some air in using the compression tester adapter.
 
Turbovanman, I can try putting a little air in the cylinder but I am doubtful that is a valve issue. I completely disassembled the heads. I checked the valves for straightness and condition. I checked the guides for clearance. I visually inspected the valve seats and the valves at the seat cut and they looked great. I also hand lapped each valve as I re assembled to check the condition of the seats. I also lapped them one at a time as assembled each valve and spring to avoid any mix up on the valves. They all showed a nice well defined even gray line on the seat and the valve.
 
Did you put a piston back in that hole?:hihi:

If you put air to it you can listen in the exhaust pipe, oil filler neck and upper intake to help narrow it down.
 
Could be a clogged lifter,or broken valve spring. A bent valve is not likely. If you got too carried away with valve lapping,lifter preload can be excesive.
 
tanman_2006


Plastic rocker button? Sucks that it might have to come out again, are you thinking bad rings?
Click to expand...

I removed the valve cover hoping for a simple problem like a rocker button but they all looked great.

Burning oil


Did you put a piston back in that hole?

If you put air to it you can listen in the exhaust pipe, oil filler neck and upper intake to help narrow it down.
Click to expand...

So that is were that extra piston came from.:D

I may try some air... kinda done chasing my tail on this one.

6.2 turbo


Could be a clogged lifter,or broken valve spring. A bent valve is not likely. If you got too carried away with valve lapping,lifter preload can be excesive.
Click to expand...

Valve springs looked great and the rocker appears to opening and closing fine. I do not think I removed to much material lapping the valves. Just enough to get a nice line.

The plan now is to remove the motor from Little D (that is for another project thread:D) and use it it Gertie. Then I can take this motor out remove the head and see what is going on. In the time it takes to figure out what is going and fix it I can have the other 6.5 in and be driving. Besides if it is a piston or ring it has gotta come out anyway. Done chasin my tail on this one. Ready to put some miles on this beastie.
 
Chevypoor said:
Turbovanman, I can try putting a little air in the cylinder but I am doubtful that is a valve issue. I completely disassembled the heads. I checked the valves for straightness and condition. I checked the guides for clearance. I visually inspected the valve seats and the valves at the seat cut and they looked great. I also hand lapped each valve as I re assembled to check the condition of the seats. I also lapped them one at a time as assembled each valve and spring to avoid any mix up on the valves. They all showed a nice well defined even gray line on the seat and the valve.
Click to expand...

No compression means a hole in the piston, cracked piston or a valve hung open. I would really try to isolate it before you tear it down.
 
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