Harsh idle after hard acceleration and deceleration...>

[Staley]

As many of you have seen I am mostly finished with my Rabbit project.
Giles built the injection pump on the diesel and it runs great and only smokes under boost.
If I accelerate hard and then decel.. sometimes the engine will idle so low that it almost dies..
and shutters VERY bad.. alternator light blinks. I have to press the gas pedal to make it idle smoother..
then the idle will settle out and run normally.  I imagine that it is fuel starvation at idle. (seems logical)
My idle also seems to be a little low.  The turbo pump that giles built for me was originally from a 1.6L
and I wonder if turning the main fueling screw in just a touch to increase idle and fuel at idle would help? any ideas
thanks
mike

[andy2]

I too had the exact symptoms with my Giles pump.Mine would idle normally when cold and then basically stall when hot upon deceleration.All you need to do is adjust the screw for the throttle lever stop to bring the idle up,Or you could up the fueling too but if your smoking under full boost then upping the fuel is not a good idea.Its a very sensitive adjustment either way so It may take a coulpe days for you to get it where you want it to idle at.I'm not sure if your pump has the other idle adjustment working on the side as mine was disconnected for reasons only Giles knows,This is the reason you'll probably only have the option to adjust the idle by using the throttle lever stop.

With the amount of fuel that Giles has set our pumps to deliver it makes this adjustment very sensitive so with the test bench you can't qiute simulate the on engine idle.

If you are not going to raise boost any you may want to decrase the fueling to clean up the smoke under full load.Do you have an EGT gauge?

[Staley]

Andy,
Thanks very much for your reply.  I will give the idle an adjustment and see where that puts me.
Thanks!
Mike

[Staley]

I have adjusted the idle up just a touch and fixed the idle problem.

BUT.. here is another wierdo problem or issue..

for the last 2 days I have an intermittent problem/issue.
If you rev the engine lets say to 4000 rpm and let off the gas..
the revs just HANG and hang and hang before slowly falling off.
If you are driving and accelerate hard in 3d gear then shove the clutch in
the engine will sit there hanging high making like 3-5 pounds of boost.
If you let the clutch out the RPMs will of course fall off.
I wonder if this is a Giles get more fuel mod or something

the car does not do this all the time.

any ideas?

[vwmike]

Kinda sounds like the residual fuel quantity is set too high. try backing that down and maybe turn up the idle advance.