20XE hunting and cutting out!

[andy_017]

I'm really stuck for ideas with this,

Basically on cold start the car is fine and will idle just above 1k which I presume is normal,no hunting etc! When the car is then left to idle it runs upto temp and starts to hunt up and down between 500 rpm and 2000 rpm and then starts cutting out! But under load the car performs and behaves as it should!

So far I have:
Changed the idle control valve.
Changed the coolant temp sensor.
Changed gearbox earth strap for new and re earther properly.
Changed alternator earth for new.
Changed headgasket (needed doing anyway).
Checked all other earths and all seem ok.
Changed MAF.

I had a c16xe in the same car before and this used to do the same thing,I don't know whether that's just a coincidence though!

Has anyone had a similar problem before? Any advice would be much appreciated!

[chimp007_uk]

air leak?

[andy_017]

Well there's no hissing coming from any of the surrounding vac pipes and no bubbling when I spray carb cleaner on there!

[16v Nova Kev]

how about your pump is that ok

[Lee]

Pump would be a good guess if its the same one that was on the 1.6.

Also get a haynes manual and scope the ICV plug through to make sure there are no breaks in the cable.

[16v Nova Kev]

he had the same problem on his other engine in that car i was thinking

[GRUNT 16V]

Swap The Icv Plug For The Knock Sensor Plug And See If That Does Anything !! Quite A Common Prob As People Seem To Get Them Mixed Up

[Lee]

Swap The Icv Plug For The Knock Sensor Plug And See If That Does Anything !! Quite A Common Prob As People Seem To Get Them Mixed Up

Colourblind people? lol

[andy_017]

Good suggestions,but with the 1.6 in i was running a gsi fuel pump which was changed for an intank astra pump when the 20XE was fitted!

Is the fuel pump earthed and if so were is the earth for this? only asking because when the car starts hunting the pitch (sound) of the fuel pump changes to a lower pitch and then rises back up to a constant again as the revs pick up :confused: unsure whether this is normal operating noise?

Maybe the pump isnt getting constant voltage or something?

[GRUNT 16V]

Get A Multi Metre In There And Check Your Getting A Constant Feed From The Fuel Pump Relay Then?????????????????????

[Lee]

Aye, could be a bad earth on the pump or a tired relay.

Turn the lights on as well and see if they dim in time with the fuel pump pitch lowering. Might even be a fubarred alternator, especially as you say the problem goes away when your driving, indicating its not consistent when its idling, but thats a long shot.

[gaznovalet]

had this problem and pain on a mates cav gsi c20xe, parts we changed were- throttle body and TPS, fuel pump relay, cranksensor as if this is at fault can affect fuel pump relay and cause cutting out. inlet manifold gasket changed and on removal had perished through in several places so cud of been slightly drawing air in. breather pipes checked incase were blocked as these are wot cause ICV to play up wen they start becoming blocked they spit oil back into ICV wich makes it stick and cause the lumpy idle.AFM and wires checked and all ok so that ruled out, ICV removed and cleaned up and refitted. spent best part of day on this and wen put back together problem still there. next day changed full wiring loom and ecu, ecu code was GY on this car and also changed the lamba sensor and car was fixed. not saying this will cure your problem but worth looking at, just leting you know the ar5e on we had with this re occuring nitemare problem on the redtops, but finaly got there in the end, hope you get it sorted as i know how you feel this car came close to being wrecked. the cav had imobiliser fitted and not a factory one unsure if this wud play any part in the problem but was disconected anyhow to rule it out.

[andy_017]

Seems to be problem solved now!

Tried a new fuel pump relay on the car which made no difference!

So then was Reading through benns Ardens blue build guide and he mentioned an oil breather jus below the throttle body which if blocked can cause idling problems,so that night I took the breather out and it was blocked solid! Tried to clear it and failed epicly,so then drilled it out,refitted and voilÃ*.... Hunting on idle cured!

The car seems to run an awful lot better now,really happy!