Bouncing revs when slowing down

[MrOizo]

Does anyone know why the engine would do this?

car in question here is a ST165 GT-Four. i thought it was to to with a vac leak which i have tracked and sorted.

only does this when coming to a stop rolling out of gear :/

[Akane]

What do you mean by "bouncing"? as if power is being applied on and off?

Now the injectors should shut off when you coast, wondering if your TPS is dead, making injectors go on and off :/

[RedMist]

I gather you are talking about hunting. I would suspect its still a vacuum leak. However its only leaking when you are pulling high vacuum. As such its going to be a PITA to find.

[MrOizo]

What do you mean by "bouncing"? as if power is being applied on and off?

Now the injectors should shut off when you coast, wondering if your TPS is dead, making injectors go on and off :/

Dont think it would be TPS as it only happens when in motion :/

I gather you are talking about hunting. I would suspect its still a vacuum leak. However its only leaking when you are pulling high vacuum. As such its going to be a PITA to find.

Yeah should be a PITA - had already been finding the first one.

The weird thing is this only happens when the car is in motion. I might just have to give changing the ECU's a change and see if that helps.

I have read up of a way of finding vacuum leaks and thats to pressurise the system with some compressed air. making/adapting some bungs on the intake sustem. would prob have to remore the w/a ic and see if its between the TB and intake plenum some where

/edit! - shoould have added that this only happens when coasting out of gear. also when i had the car up on stands the other day, i had it idling in first gear and it was bouncing again like 1000-1500-1000-1500-1000-1500 (rpm's of course)

[MrOizo]

anyone?

[MrOizo]

Wicked!

seem to have fixed this. changed the ECU and drove much better.

Opened up the ECU and had a look at the board. seems that resistor is fried i know this is relatively common.

its R422 or something like that which is all nicely burnt

[sergei]

Hmm really strange, ressistors don't usualy fail, transistors do, but you say R422, that is defently resistor....