Idle Too Fast When Hot

[Ozzie]

Hi guys,

 

Could someone have a stab at this one please?

 

'99 1.6 runs fine, ok when cold but when hot the tickover is high - 1300 or higher.

If the engine is switched off and restarted immediately it's fine for a while but after a short drive the problem returns.

 

I haven't replaced anything yet , just wondering where to start. Anything simple to check first ? !

 

TIA

[Guest Colin Hunter]

Hi Ozzie.

 

The idle speed is controlled by a "stepper motor" which is basically an air valve which opens and closes to allow the engine to run when the throttle is shut. It may not be closing properly, hence the high idle speed. If it can be removed, take it off and clean it and make sure it moves freely. Also make sure there is no muck in the housing it lives in that may prevent it seating properly. That, as far as I know is about all you can do with these modern Petrol injection systems. My last PI job, ( a 2.0i MG Montego. Yes THAT long ago) had loads of adjustments you could make and things you could do when it acted up, and they usually did the trick. No such joy these days I'm afraid. It's all sealed and controlled bya "Black Box"!!!

 

Cheers. Hope this helps. :blink:

[Ozzie]

Hi Ozzie.

 

The idle speed is controlled by a "stepper motor" which is basically an air valve which opens and closes to allow the engine to run when the throttle is shut. It may not be closing properly, hence the high idle speed. If it can be removed, take it off and clean it and make sure it moves freely. Also make sure there is no muck in the housing it lives in that may prevent it seating properly. That, as far as I know is about all you can do with these modern Petrol injection systems. My last PI job, ( a 2.0i MG Montego. Yes THAT long ago) had loads of adjustments you could make and things you could do when it acted up, and they usually did the trick. No such joy these days I'm afraid. It's all sealed and controlled bya "Black Box"!!!

 

Cheers. Hope this helps. :blink:

 

Thx Colin , looking at the Haynes manual the 1.6 has a throttle potentiometer and an idle speed auxiliary air valve , both are removable.

 

Unfortunately it only states how to remove and refit.

 

Is there anything to check , clean etc. ?

 

It also advises to disconnect the battery prior to removal , is it a major problem with the ecu losing settings on the Xsara ? I have the radio code !

[Guest Colin Hunter]

Hi again Ozzie.

 

I'm afraid I'm not very "up" on petrols these days, but if you can get the auxy air valve off, start by cleaning it up and make sure it can move freely. Check the connections on your sensors and try cleaning them with some electrical switch cleaner (Although if it's running OK otherwise they're probably OK)

 

The ECU shouldn't lose any settings if you disconnect. After all it's switched off every time you stop the engine! My lad's ZX works OK after disconnecting. As long as you have the radio code you'll be OK although I wouldn't bother disconnecting the battery to check out engine sensors and the like. They're all dead when the ignition is off anyway. It's just Haynes riding the safety first bandwagon!

 

Chers. Hope this helps. <_<