clanking noise 2005 duramax
 

I have an 05 base model work truck and it seem to run fine only it makes a loud clanking noise(like a powerstroke) when at low throttle. Seems to go away when i add more throttle and the turbo engages. The rpm gage doesn't seem to bounce. I have recently replaced the #2 injector plug when that went out. Would this possibly be caused by bad fuel or maybe the #7 injector plug? Last night i had the guy at o'reilly auto check for codes and it came up clean. Does anyone have any ideas one what this could be? I am trying to keep it out of the shop if i can.

#7 plug would throw a light and code, would help to be able to hear the noise.

I figured it probably would. What about a fuel filter? Could that cause this or would it cause bad performance no matter how much throttle was given?

usually a bad fuel filter will cause it to flat line rpms when you floor it, itll run like crap and would set a light and code for low rail press during power enrichment.

ok so i just had the truck scanned at the machanic shop and this is what it came up with.\
po300 random misfire
po302 2 misfire

po303 3 misfire
po305 5 misfire
po308 8 misfire
po675 glow plug 1 control circuit

What would be the cause of all these going bad at the same time?
Would this control circuit cause any of these other issues?

you sure they had the correct vehicle put into the scan tool? have you checked your fuel quality? never seen it set a missfire code but check your ficm harness for chafing on the bracket beside the alt.

I am pretty sure he put the info in correctly but i didn't watch him. How would i go about checking the fuel quality? Before this happened i filled up in a small town gas station. i have since filled up and dumped some seafoam in the tank and have gone about a quarter tank since. I just checked the harness and no wear and tear at all.

id drain some fuel out of the filter and see what it looks like, see if it smells like gas or kerosene, leave it set overnight and see if any water is in it. the random missfire sounds like bad fuel but I could be wrong.

Ok so I pour myself a half glass of diesel last night. It looks and smells fine. Before I did this I opened the plug to see if any water came out but nothing. Not sure what else I can do. Is it worth my time to change out the fuel filter? Or does this seem like its something more electronic now?

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Well i was wrong. there is water and a little dirt in the fuel. I am guessing that that is the issue i am having. Whats the best way to take car of this problem? Do i need to drain the whole tank and clean it out or add something to it?

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OK problem solved! I drained out about 10 gallons of fuel from the tank and replaced the fuel filter with a WIX High inefficiency fuel filter. put about a 50/50 mix of diesel 911 in the fuel filter and half the bottle in the tank. fill the tank back up with new diesel and drove for about 90 miles. It drives great now with no noise. Anything else you think i should do?

Thanks for all the help.

hopefully youll be ok, id keep running some treatment through it for next few tanks and thats about it