Rav 4 - tickover, Idle speed, far too fast ! - Help, please

[AztecFire]

Hi All, - Newbie here, and not sure how to post this ??....but any help appreciated ! 

Rav 4 - Mar. 2002 - 2.0l petrol - 3dr. Hatch - (Varient ACA20 - JTEYH20VX )

Car was running fine, until water hose came off, overheated, and blew Head Gasket :-((  (Not HP !!  )

Put into (proper) Repair Garage, who stripped and skimmed head, built up engine, and got starting, and running...........but :-((( tickover / idle speed is waay waay too high, (800+ rpm). 

Garage Owner has stripped out and cleaned Throttle Body, replaced MAF sensor, air filter, etc. etc. and has brought in (two) "specialist palz" to help, but still, - after two months, -  can't get it to run right !. Starts instantly off the key, but engine continues to "race" at far too high revs !. Now suggesting I buy a new ( i.e. s/h) Throttle Body "to see if that might work". However, as the tickover was absolutely fine, before the stripdown, I don't see what "fault" could have been caused to the t/b just sitting on the floor, beside the engine !.

I've read a few comments on here, relating to emi system, ECU reflashing ? (- don't know what that is ),

- would anyone have any ideas of what to try next..... ????     

[IanML]

Have either of the specialist palz checked for fault codes?

I Believe the throttle body is very expensive, and the seat of the problem is probably the Idle Air Control Valve attached to it - electrical connection ok?  It may have picked up some dirt - remove and clean it.  If you Google "RAV4 Idle Air Control Valve" you will find quite a lot on the subject, mainly people in the US who do a lot of DIY..

[craggle]

It could be an air leak in the inlet manifold. If air gets in to the engine behind the throttle body and air flow meter it can lean the mixture making the engine rev more and the throttle body can't control it.

Maybe a gasket or rubber seal is misplaced or damaged but I don't know the engine so can't really suggest where to start looking.

Craig.