Delay lifting off throttle?

[Ross]

I've covered 400 miles since the rebuild now and I can't figure this one out. When lifting off there's a 2s delay, like the throttle is sticking. It is only when the engine is under load, free revving is fine. It isn't such a problem driving lazily, but make a quick shift and the revs rise about 500rpm before dropping.

Any ideas? I've slackened the throttle cable off, revs return to idle nice n quick just with this delay first... Anything that could be sticking or causing this?

[A80Avant]

are you pressing the clutch faster than you are lifting off?

[rj scotty]

I have a tendency to do that when driving the s2 being used to a slow revving diesel

[dest]

Have you tried removing the throttle damper to see if it makes any difference?
Idle speed valve or whatever its called?

[driftin jo]

If your ISV is jammed open slightly you can get boost past it when you lift off giving the same result as if you haven't shut the throttle for a few seconds until the boost dies off.

[s2driveruk]

i have this on my pugeot 306 and it drives you nuts after a while...I think its probably the ISV gummed up

[Ross]

I gave the ISV a clean, as it was a slight issue before the rebuild, but it's definitely more severe now - I wonder if I need to take it off and do a more thorough cleaning... It's only helpful if you want to down-shift for a steep hill or overtake... (blips it for you), everywhere else it's annoying

It is as if the throttle is holding say 20% open for 2-3s after you let it off completely. If you back off, you feel the engine still pulling and vac is at ~0.5bar, then it drops off completely after the delay. I can only think it's either the ISV sticking or the throttle cable sticking due to a bitof engine movement under load.

[s2driveruk]

get a can of egr cleaner, that stuff will shift anything lol

[Sonic]

Make sure the throttle body isn't getting jammed by the bonnet, this sounds similar to the problem i had with the reverse inlet, where accelerating caused the front of the engine to lift, jamming the throttle open

[Ross]

Had a few mins tinker time today and this problem is now sorted... lived with it for a while but since putting the car back on the road last month it's been driving me nuts.

It was the throttle damper in the end - I was certain I'd swapped it as I had a spare, obviously not... it seems fine until you hold the throttle open for about 5s and it was getting stuck at full extension when the throttle was release (oooh errr), holding th throttle part open before it popped back in.

I slackened the thing right off so it barely does anything and I can't believe how much easier/quicker it is to make a smooth gear change!