injector knock?
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Freshman User
Joined: Feb 2015
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Did what tugly said. And pre set the tourque wrench to 75 inch pounds. And none of them moved. Unpluged each injector at idle and they all made the engine stumbled. Replaced the o rings anyway and started up the truck and got it warm then re torqued. Drive the truck 100 miles and is still making the same noise. No difference what so ever. Now im just gonna do the hutch mod and see if that works. I will be posting a video of that too.
Posting Guru
Joined: Sep 2014
Posts: 2,404
Likes: 3
From: Asheville-where weird is
In addition to the Hutch Mod, you may want to consider doing the FRX or a full regulated return since o-rings and torquing did not help.
You may want to do the Harpoon Mod as well while you are in the tank...it makes topping off the tank a lot faster.
You may want to do the Harpoon Mod as well while you are in the tank...it makes topping off the tank a lot faster.
Hotshot
Joined: Jan 2011
Posts: 18,849
Likes: 179
From: Puget Sound
Well - good work! Sorry that didn't fix it, but it's worth a try because it's a lot cheaper than new injectors. I think you have a shot injector at this point, but you won't want to spend the money on injectors until you are 100% sure there is no air in the fuel (Hutch mod). I'm here with my hand in the air to make a Boy Scout oath that air in fuel damages injectors quickly. I'm still waiting for the return of my damaged spare injector.
Laughing Gas
Joined: Aug 2008
Posts: 823
Likes: 5
From: Dallas, Oregon
I've been through this one with my truck. I never did find out what was causing the knock. I did determine which cylinder was knocking (it was #7 - the rear one on the passenger side) by unplugging injectors while idling.
I made a Break-out Box from an old UVCH and parts from the electronic store. It made it easier to experiment.
I tried the following:
Replaced all injectors with Ford remanufactured AB units.
Replaced both UVCH's.
Torqued injectors and rockers.
Installed regulated fuel return.
Installed High Pressure Oil cross-over pipe.
Increased Fuel Pressure (shimmed regulator spring)
Tested High Pressure Oil output/pressure.
I bought a good used motor five years ago, so I decided to just run the old engine until it blew up. I finally got tired of waiting for it to fail, so I replaced it this week. Other than the knock and a leaky front oil seal, it was running fine!
You can determine if it is an injector knock by driving the truck at 55-60 mph on a flat road and pulling your foot off the accellerator. If the knock quits (the injectors quit squirting under this condition) then it is related to injectors. If it is mechanical, there should still be some noise.
Good luck! I want to dismantle the old motor to do a "post mortem" but my wife wants me to just sell the core complete to get it out of the shop. She's sort of compulsive!
I made a Break-out Box from an old UVCH and parts from the electronic store. It made it easier to experiment.
I tried the following:
Replaced all injectors with Ford remanufactured AB units.
Replaced both UVCH's.
Torqued injectors and rockers.
Installed regulated fuel return.
Installed High Pressure Oil cross-over pipe.
Increased Fuel Pressure (shimmed regulator spring)
Tested High Pressure Oil output/pressure.
I bought a good used motor five years ago, so I decided to just run the old engine until it blew up. I finally got tired of waiting for it to fail, so I replaced it this week. Other than the knock and a leaky front oil seal, it was running fine!
You can determine if it is an injector knock by driving the truck at 55-60 mph on a flat road and pulling your foot off the accellerator. If the knock quits (the injectors quit squirting under this condition) then it is related to injectors. If it is mechanical, there should still be some noise.
Good luck! I want to dismantle the old motor to do a "post mortem" but my wife wants me to just sell the core complete to get it out of the shop. She's sort of compulsive!
Tuned
Joined: Oct 2012
Posts: 391
Likes: 9
You can determine if it is an injector knock by driving the truck at 55-60 mph on a flat road and pulling your foot off the accellerator. If the knock quits (the injectors quit squirting under this condition) then it is related to injectors. If it is mechanical, there should still be some noise
Thread Starter
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Freshman User
Joined: Feb 2015
Posts: 28
Likes: 0
I've been through this one with my truck. I never did find out what was causing the knock. I did determine which cylinder was knocking (it was #7 - the rear one on the passenger side) by unplugging injectors while idling.
I made a Break-out Box from an old UVCH and parts from the electronic store. It made it easier to experiment.
I tried the following:
Replaced all injectors with Ford remanufactured AB units.
Replaced both UVCH's.
Torqued injectors and rockers.
Installed regulated fuel return.
Installed High Pressure Oil cross-over pipe.
Increased Fuel Pressure (shimmed regulator spring)
Tested High Pressure Oil output/pressure.
I bought a good used motor five years ago, so I decided to just run the old engine until it blew up. I finally got tired of waiting for it to fail, so I replaced it this week. Other than the knock and a leaky front oil seal, it was running fine!
You can determine if it is an injector knock by driving the truck at 55-60 mph on a flat road and pulling your foot off the accellerator. If the knock quits (the injectors quit squirting under this condition) then it is related to injectors. If it is mechanical, there should still be some noise.
Good luck! I want to dismantle the old motor to do a "post mortem" but my wife wants me to just sell the core complete to get it out of the shop. She's sort of compulsive!
I made a Break-out Box from an old UVCH and parts from the electronic store. It made it easier to experiment.
I tried the following:
Replaced all injectors with Ford remanufactured AB units.
Replaced both UVCH's.
Torqued injectors and rockers.
Installed regulated fuel return.
Installed High Pressure Oil cross-over pipe.
Increased Fuel Pressure (shimmed regulator spring)
Tested High Pressure Oil output/pressure.
I bought a good used motor five years ago, so I decided to just run the old engine until it blew up. I finally got tired of waiting for it to fail, so I replaced it this week. Other than the knock and a leaky front oil seal, it was running fine!
You can determine if it is an injector knock by driving the truck at 55-60 mph on a flat road and pulling your foot off the accellerator. If the knock quits (the injectors quit squirting under this condition) then it is related to injectors. If it is mechanical, there should still be some noise.
Good luck! I want to dismantle the old motor to do a "post mortem" but my wife wants me to just sell the core complete to get it out of the shop. She's sort of compulsive!
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No not yet but i checked my fuel pressure. And it was only 27 psi. I disconnected the tank side of the fuel pump and ran it to a bucket of diesel. And the pressure stayed the same. Im guessing this is why it runs rough when its warmed up because it uses more fuel when warm. Now i just have to see if its the fuel pump of the pressure regulator. And once i get the pressure back to normal im probably going to have to change my #8 injector because it might be ruined.
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