Slow return to idle

[James McGrath]

One thing I've noticed about my LS more recently is that it takes a few seconds for the engine to return to normal idle speed.

It just doesn't seem to return to idle as quickly as it used to.

For example, if I dab the throttle the engine will rev up quickly as normal but then stay there for a couple of seconds after I've taken my foot of the pedal then return to normal idle speed.

Apart from, that she's driving better than ever at the moment.

Does anyone have any ideas as to what might cause this to happen?

Clogged injector maybe?

[TurboDan]

Id clean the throttle body and go from there.

[James McGrath]

Id clean the throttle body and go from there.

That was one of the first things I did when I first started driving the car 3 years ago and it did make quite a difference.

I'll take the top hat off tomorrow and see how it's healed up and de-clog it again.

[btcctroy]

I'm pretty sure theres and idle stepper motor on those. May need a clean out with carb cleaner

[James McGrath]

I'm pretty sure theres and idle stepper motor on those. May need a clean out with carb cleaner

Interesting. Done a bit of googleing and yes it does have one. I'll give it a good clean and see what happens.

[planetc]

Clean the idle control valve, and replace the throttle body gaskets, two of them, one at the top and one under the throttle body.

[James McGrath]

Clean the idle control valve, and replace the throttle body gaskets, two of them, one at the top and one under the throttle body.

Any idea where to get the gaskets from?

[John Owens]

I'd try autovaux for the gaskets mate

[James McGrath]

I've just tried autovaux and they said the one under the throttle body has been discontinued.

However they did have the rubber one at the top for the top hat. It should arrive in a couple of days.

I don't know where I'm going to find the lower one from though. Genuine parts search don't have it either.

[planetc]

The base gasket is flat waxed paper, so you should be able to make one with some gasket paper carefully cut. The upper one isn't the rubber one, there is one between the top and bottom sections of the throttle body itself. Most of the time it's the base one that causes the problems though.

[James McGrath]

Oh well. I needed a new rubber one anyway.

Am I right is saying that the part numbers of the gaskets you are referring to are:

17087373 Upper gasket

90412407 or 90412408 Lower gasket

They have the lower one but not the upper one.

And what lower one should I go for 90412407 or 90412408?

[planetc]

No idea on part numbers I'm afraid James, been too long since I dealt with them to remember.