idling irregularly
 

Rover 75 2.5 v6 petrol auto

When coming to a standstill after a run, put in Park or Neutral, normally engine should idle steadily at 650 rpm or so.

I've noticed that mine sometimes seems not to idle steadily, but to gently rise and fall between about 600 and 1200 rpm, each rise/fall cycle taking about 1-2 seconds

No other obvious symptoms or ill-effects. No problem driving off.

Problem seems to go away and idle ok if I turn engine off and on again.

Only seems to happen when engine is warm after a run, and even then not every time; and not when starting from cold

Any ideas please.

thank you. David

I'd start my investigation with the breather hoses and the idler set-up on the throttle body.

Mine sometimes did this and when i blipped the throttle it became steady again. I ended up changing the throttle assy and it stopped the problem. i do believe it was an air leak somewhere on the throttle assy but never investigated further

that seems to concur with similar comments I've read elsewhere which also suggest taking off the idler control valve and giving it a good clean, so I'll have a look when I get a chance. Will be a new thing for me so I hope I can get it all back together without making it worse, or I might be back for more advice!

Throttle body rebuild kit from Rimmer's will sort the issue.

"Rebuild kit"? Is that this:
https://rimmerbros.com/Item--i-MKG100260L

David,

I too have had this intermittent phenomenon for years and the idle air control valve repair kit didn't make any difference. I've checked the throttle cable adjustment and the crankcase breather tubes are fine. Unfortunately the cause eludes me at the moment. I have identified a poor electrical connection on my power VIS actuator plug which is on the list of things to do when time allows.

If you find out what it is please post the answer!

Simon

Next time it does it, tap the IACV valve with the handle of screwdriver, if the idle settles down then replace the valve or try giving it a good clean.

That's the fella. The plastic bit often sticks after years of service!;)

thank you, I'll try that.


Thank you, I'll get one in case just cleaning it doesn't work.