so i went to a performance shop to have a set of gauges installed on my 07, everything went well but they were concerned the truck is making too much noise at idle(it knocks) i brought it to the dealer last year about it and they looked at it for 5 minutes and said it was fine. the shop that did the gauges ran a test on the injectors shuting them down 1 at a time -all good fuel pressure good everything seemed ok but they think i have a internal issue. truck is stock except a intake and cat back exhaust. truck runs 100% and has 28k miles. another thing with the boost gauge when you juice the fuel to it the boost gauge goes up to about 35 psi and then jumps down to 20 and then back up, needle is all over the place, but just lugging it up a steep hill it will hold steady at 20 psi they tried 2 different gauges checked the waste gate they were stumped. any ideas?

 

Check for a boost leak. You should jump up to about 32 psi then fall back down to 28 psi. As far as the knocking. It is probably carboned up injectors. Get a heavy load and pull the crap out of it keeping the EGT's up to around 1000 deg. That should fix it up.

 

the shop that did the gauges found a intercooler boot loose but i still have the spike, ill have to look into it a little more tommorow, as for carbon on the injectors, i pull probably once a week with it but ill get her good and warm next time for sure hopefuuly that solves it

 

I have thought my 07 5.9 had a LITTLE bit of a knock but nothing I would be concerned about. I pull with it regular and doesn't take long to get it to 1,000 degrees. More like 1200-1300 in an instant if your not watching it.

 

Mine knocks too. Not all the time but most of the time when waarm. Dealer said normal.

 

yea mine seems to knock when warm, in the winter its nice and quiet

 

I had a slight knocking sound and found that the brackets that hold the injector lines had come loose and that completely fixed my noise.

 

My 07 5.9 has the same noise at idle and I have done some research on this also. If you search on this forum you will find a lot of threads and info on this issue and it sounds like a lot of people have fixed the problem by changing the position of the cp3 pump gear. Do a little searching, there are threads on here that are very in depth on the issue and will explain it alot better than I am. When I get time I am going to give it a try.