DG holds little bit when accellerate

[lievenn]

Hi,

When I accelerate, the bus holds a couple of seconds before acceleration comes up. It's just like somebody is braking a little bit. Sometimes I can hear a "bang". Yesterday I've checked the pre ignition with a timing light. When I give gas, the ignition holds or even turns back before moving (= the "braking" when accelerate).

It's a new vacuum pipe and I've test the vacuum module on the ignition and it seems ok (suck on the pipe connected to the vacuum module on the ignition and hold i a couple of seconds).

How can I test which part is bad (ignition, carb or the vacuum module on the ignition)?

[CJH]

That sounds like it could be the accelerator pump on the carb - some discussion here. If it's this then it could just be the adjustment of the cam or it could be the rubber (split) or the spring (weak) in the diaphragm.

[lievenn]

Interesting topic. I have a new accelerator but didn't change the accelerator quantity. The problem was already there before replacing the accelerator but it's worse now.
So this afternoon I'v changed the quantity from minimum to just before max and checking the influence: in first gear the car accelerates better, no "banging or braking". In the other gears: still "banging and braking".