Idle adjustment screw

[Boat]

Hey all. I have that little "Blub" in the motor when idling up. Motor runs like a swiss watch except for this one little thing. Idle RPM is 500. Its that little Stutter, Blub, hesitation when idling up while docking or etc. My idle screw is out 1.5 turns does that sound like a symptoms of a tad rich on the idle?

[edwardc]

Hey all. I have that little "Blub" in the motor when idling up. Motor runs like a swiss watch except for this one little thing. Idle RPM is 500. Its that little Stutter, Blub, hesitation when idling up while docking or etc. My idle screw is out 1.5 turns does that sound like a symptoms of a tad rich on the idle?

Try tweaking your timing. This can effect the transition between the idle jet and the main jet, which is usually the cause of the stutter while throttling up.

[roadnsky]

Another place to look.
Here's a previous post from Don that might also come to bear on your "stutter"...

"At approximately 1100 RPM, the main discharge nozzle pretty much drops out and the idle system is supplying most of the fuel to the engine, and if the lower of the two idle ports is clogged, the mixture will become very lean during the transition to idle. If the engine can get to idle, and the upper port is open, it will able to carry the load, but only at around 800 RPM.

This situation is sort of like a flat spot during acceleration, only in reverse. The lower of the two idle ports is referred to by some (including the writer) as the "off idle" port, because this port has to kick in as you move the throttle forward to get you "off of idle" and on to the main discharge nozzle. If the lower port is clogged, you'll feel a flat spot until you get to the main discharge nozzle - if you can even get to the main discharge nozzle.

As you decelerate, you're depending on the lower idle port once again to kick in to carry you smoothly as you transition between the main discharge nozzle and the upper idle port."

[JOHN COOKSON]

When you get 'er idling correctly adjust the idle speed and idle mixture until you find the sweet spot for idle speed and idle mixture for your particular engine. Mine ended up being 1 1/4 turns off the seat and 600 RPM. Each A4 is a bit different.

ex TRUE GRIT

[Boat]

it will idle real nice at 400 even. nice and quiet. if i jump the throttle up to say 1000 quick, i get the blub. if i start at around 600 or higher, no blub. doing the annual maintence so i will be checking distrubutor, weights all the stuff. it has always done it but i have always had the idle mix at 1.5 out. will try some others