Absolutely, and the reason most q-jet rebuilds are NOT successful. The idle tubes are pressed into the casting, and it is not possible to clean in and under them without pulling them out.
They can be "rodded" our with a small piece of wire, but there will be considerably dirt/debris under them which will often get sucked right back into them when it's placed in service.
Keep in mind that ALL of the fuel at idle has to pass thru the idle tubes, past the idle down channel restriction, past the ends of the mixture screws and into the engine from the tiny holes just under the throttle plates. Some idle fuel will also be pulled in by the exposed portion(s) of the transfer slots.
The idle system also feeds fuel thru the tranfer slots as throttle angle is increased. This helps with transition onto the main curcuit, and it continues to feed the main curcuit at lower throttle angle(s).
We alway pull and clean the idle tubes by running precision drill bits thru them. The removal procedure is outlined in our book.....Cliff
