fast idle mot fail [Archive]

kermack

09-12-2009, 22:45

I think the engine is getting to much petrol so that might be why is idling over to fast. the idle screw is set at its lowest point and still to height so can anyone tell me how i can adjust the amount of petrol thats flowing into the car

MatBrown

09-12-2009, 22:51

Have you tried cleaning the 'idle speed control valve'?

Mat.

kermack

09-12-2009, 23:19

no but I'm quite positive its the petrol cause been going through petrol alot faster this last couple of month

white16valver

10-12-2009, 14:23

The Idle Speed Control Valve will control what speed it idles at - so if it's idling higher it will naturally use more petrol.

Question to the clever bods - is there a fifth/cold-start injector that could be stuck open?

cliokiz

10-12-2009, 17:24

Yes there is

Wobba

11-12-2009, 16:27

What revs does it sit at at idle?

High idle could be a number of things.

Cleaning the ISCV is the first port of call. Carb cleaner and cotton buds do wonders here!

Secondly, check the throttle butterflies are fully closed on idle.

Third, check the pipework going into the inlet manifold. Pay attention to the vacuum hoses and jubilee clip or replace. the one after ISCV going into inlet manifold is quite common one to need a jubilee (had this problem after I fitted megane engine).

Fourth, whip the ECU out and check for scorch marks on the board (both sides). A blown board can cause this (had two blown on me, so I know the pain).

Fifth could be dodgy flywheel sensor. I had this briefly on mine but solved it within a couple of minutes (had metal shavings fouling the magnetic field, I just blew them out and cleaned sensor).

You say it is feeding too much petrol? If so then yea it could be a stuck 5th injector, if so the inlet manifold would probably be flooded with petrol. Whip the airbox off, take off throttle body...if it's flooded it will stink of petrol and you may be able to poke something in to see if there is petrol lying on the bottom of the inlet.

It is possible to change the 5th injector with the engine in car I think but it's quite a fiddle!

Evogone

11-12-2009, 16:50

CTS sensor or wiring would make it run rich when hot.

Wobba

11-12-2009, 17:25

CTS sensor or wiring would make it run rich when hot.

Yea, check wiring. CTS sensor is only a tenner from GSF.