MR2 rev3 Turbo Poor Idle (revs hunting)

[rob6539]

Hi guys, please can I tap into your vast knowledge again?

My rev3 turbo has began to idle poorly, the revs either seem to be very high on tick over (around 2000) or the revs are hunting (surging between 1500 to 2000).

It happened after an enthusiastic drive.

This is what I’ve done so far, but without any success:
- Replaced air hoses from Turbo to inlet manifold and checked for air leaks.
- Removed throttle body and cleaned the butterfly valve.
- Removed and cleaned the Idle Control Valve.

I suppose the next step will be checking sensors?

Please can you advise the best way to check sensors, (other than buying a new one!) and which sensors might cause the idle issue, if broken?

Or if there is anything I might have missed?

Thanks guys, would really appreciate your help.

[mrdb]

Hunting like that is usually an air leek around manifold. Could be injector seal or manifold gasket area.

[rob6539]

Found the sneaky culprit.

There is an air leak at the back of the inlet manifold on the right side if your looking from the rear of car. Unfortunately the site won't let me place a pic via an URL, which would of helped greatly.

I've found a pic of a rev3 manifold on ebay and it looks to have a rubber bung on it.

On mine however it seems to be an empty hole, without a thread?

I've read somewhere that it should be blanked off, is this correct? Should it have a nipple on like the one on the left of the manifold? (Used for the hose which feeds to the IACV sender unit)

Think I already know the answer to this, but am I gonna have to drag the whole manifold off in order to fix it?