EGR pipes???
 

I'm currently removing my upper plenum for an injector upgrade. I noticed that the tubes coming from the EGR to the intake manifold are clog up with carbon deposits. This might be the reason why my gas mileage is low. Is there a way to clean the tubes without removing it from the EGR? Any solvent maybe?

I call them bottle brushes. You need the kind with wire bristles. You can buy kits of various sizes or you can just buy the size that you need. BOTTLE BRUSH SAMPLE

I can't say where I've seen them for sale except for industrial supply places like McMaster-carr and the like. Without those you just use wire and screwdrivers.

It's quite common for the egr passages to clog up over time. The older the motor, the faster they clog....... Oil blow-by.

Thanks for the advice, but I want to clean the tubes without removing the it from the EGR. It's alot of hazzle to remove it from the EGR. I already started scraping the carbon build up from the tube. I got the holes going inside the upper plenum cleaned but I am worried about the carbon that I scarped going inside the combustion chambers.

pipe cleaners/wire brush + vacuum
that should take care of those deposits.

I don't think the carbon would do any damage, probably just get pushed out the valves. It's non metalic and usually something that occurs in any engine