need help with a knock!!

Robertp

Robertp

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Joined
Feb 8, 2007
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about three weeks ago I had and injector body crack while driving. Pulled off to the side of the road after noticing a bad fuel smell. Found the oil level way over full and the under side of the truck soaked in fuel and oil, from the breather. Pulled the injectors sent them out. Replaced the cracked injector body and got some new nozzles put on. Reinstalled all of the injectors changed the oil. (Drained out about 7 gallons of oil and fuel mixture) started the truck up idled perfect nice and smooth no smoke at idle at all. Drove up and down the street noticed a what seems to be a timing induced knock. Starts as soon as there is a load on the engine and is completely gone by 2000 rpm. Programmed the ecm back to stock the noise lessened but was still there. Once again I sent my injectors out to have them tested all tests come back golden. (Again I have to thank industrial injection for putting up with me through all of this) I got my injectors back again today and installed them. Knock still there, and gets worse when i put the program back in the truck. Checked all sensors for proper connections all good. Drove the truck home runs great still has a ton of power runs and idles great still. Just have this annoying knock from let’s say 1300-2000 rpm then it’s gone. im at my wits end with this thing. Oh yeah one more thing I put a new stock cp3 on thinking maybe that could be the cause. Any and all info would be appreciated. Thanks Robert. Feel free to ask any questions im at my wits end with this knock.
 
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Do you have the plug to bypass injectors off the rail? That helps when trying to pin point a cylinder.
 
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Snedge said:
Do you have the plug to bypass injectors off the rail? That helps when trying to pin point a cylinder.
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yes i do. i will be doing that this weekend. along with my new stage 2 cp3. im downloading the older smarty file now woth no rail pressure to see if that changes anything.
 
Robertp said:
wow seems like im not the only one having this exact same issue. hopefully we can all get it resolved quickly. thanks for the link.
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no, you aren't alone. My truck was knocking extra hard yesterday and I was wondering if anyone could find a solution....
 
Alright, good luck. I have a feeling programing is not your issue though. What cylinder was the one with the cracked body?
 
Snedge said:
Alright, good luck. I have a feeling programing is not your issue though. What cylinder was the one with the cracked body?
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it was cylinder number 4.


i have an update for everyone. i took the beta smarty off and programed it back to the april 23rd software, the knock is 90% better. i will have more results in the morning for everyone.
 
Im sure im not right on this i probley need to stay on the dmax board lol. My buddy has the same problem with his 04 dodge isb motor. Put a lift pump on it seem to smooth it up. And gave him his top end. robert he has the same set up u do. Acutally u can find him on the fourm extreme cummins. Fass 150 sovle his problem and gave him top end he never knew he had.
 
Robertp said:
it was cylinder number 4.


i have an update for everyone. i took the beta smarty off and programed it back to the april 23rd software, the knock is 90% better. i will have more results in the morning for everyone.
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My knock goes away after a program change...run it for a few days and see if it returns. Its worse with some programs compared to others.

i ran a reduced timing tune for a while and the problem was almost gone but the truck wasn't very drive-able...unless i had nitrous to spray at it. (The reduced timing program was PPE's nitrous tune.)
 
duramaxin14 said:
Hey 973604x4 thats a pretty good burnout for a gas job 360:hehe:
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haha Oh yea let me tell ya! :hehe:

years ago when i first got on the forums, i drove a 97 half ton with the ol 5.9 gas engine. I just kept the name when I got my cummins and still use that name on all boards so im not hiding behind a keyboard with a mysterious identity :hehe:
 
973604x4 said:
My knock goes away after a program change...run it for a few days and see if it returns. Its worse with some programs compared to others.
its not completely gone but its a whole lot more managable. i only hear it in the begining of second gear. i used to hear it in second through 5th.
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97 i here u i had a 01 with a 318 in it i had a hypertech programmer which i still have and trying to sell. Intake and exhaust 38inch tires and 20 inch rims. Had tranny work done to it also. quickest i ran with it was a 17.1 and i dont recall the mph. But i didnt really think that was to bad for 3.55 gear ratio and big tires and rims. mpg was a whoppin 8 with 93 octane 6 with 87 octane.
 
973604x4 said:
no, you aren't alone. My truck was knocking extra hard yesterday and I was wondering if anyone could find a solution....
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how long have you been battleing this issue?
 
Robertp said:
how long have you been battleing this issue?
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since my injector install, about 2 months. What size II injectors are you running?
 
Well on the way into work, I noticed that the knock is still there just not as pronounced. So please keep the ideas rolling!
 
well today i put it on the DRBIII ran the injector cut out tests and cylinder performance tests. all tested good. cylider performance came back perfect. funny thing after i drove the truck while running the injector cut out tests. the knock is gone. not there at all. its got me more confused than ever. but happy that the knock is gone.
 
still there on and off. im not too sure what it is. but it is alot quieter than it was before. it just sounds like a timing knock.
 
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