idling irregularly

david75 · 29th January 2020, 21:39

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

Lord of Hog · 30th January 2020, 06:45

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

stocktake · 30th January 2020, 07:22

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

david75 · 31st January 2020, 21:42

Quote:

Originally Posted by stocktake

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!

trikey · 31st January 2020, 21:45

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

david75 · 31st January 2020, 22:25

Quote:

Originally Posted by trikey

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

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

Phil-T4 · 1st February 2020, 11:12

Quote:

Originally Posted by david75

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

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.

david75 · 1st February 2020, 22:48

Quote:

Originally Posted by Phil-T4

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.

thank you, I'll try that.

Quote:

Originally Posted by roverbarmy

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

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

trikey · 1st February 2020, 22:58

Quote:

Originally Posted by david75

thank you, I'll try that.

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

The plastic 'T' Piece deforms over time and catches on the throttle body.

david75 · 20th February 2020, 22:35

Quick update: I've bought the kit with replacement gasket etc... but since then the original symptom has completely gone away! So I think I'll leave it alone unless the problem comes back, but at least now I am equipped to deal with it straight away if it does recur. If that happens, I will report back on this thread.

29th January 2020, 21:39	#1
david75 Posted a thing or two Rover 75 2.5 V6 Conn SE, 04 Join Date: Sep 2012 Location: Southend Posts: 1,176 Thanks: 544 Thanked 302 Times in 165 Posts	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

30th January 2020, 06:45	#2
Lord of Hog Gets stuck in Rover 75 2.5 V6 in Wedgwood Blue Join Date: Dec 2015 Location: Felbridge, East Grinstead Posts: 982 Thanks: 250 Thanked 294 Times in 206 Posts	I'd start my investigation with the breather hoses and the idler set-up on the throttle body. __________________ Conformity is not morality. Consensus is not truth.

30th January 2020, 07:22	#3
stocktake Vis Whiz Rover 75 2.5 auto Saloon Join Date: Jun 2007 Location: LEEDS Posts: 20,591 Thanks: 2,057 Thanked 3,056 Times in 1,621 Posts	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 __________________ Dave... Lost a few stones and a Gall Bladder and part of a bile duct and all of my dignity in the suppository incident

31st January 2020, 21:45	#5
trikey Premium Trader Rover 75 Join Date: Nov 2010 Location: Devon Posts: 33,774 Thanks: 8,837 Thanked 14,831 Times in 8,030 Posts	Throttle body rebuild kit from Rimmer's will sort the issue. __________________ Lest we forget..

20th February 2020, 22:35	#10
david75 Posted a thing or two Rover 75 2.5 V6 Conn SE, 04 Join Date: Sep 2012 Location: Southend Posts: 1,176 Thanks: 544 Thanked 302 Times in 165 Posts	Quick update: I've bought the kit with replacement gasket etc... but since then the original symptom has completely gone away! So I think I'll leave it alone unless the problem comes back, but at least now I am equipped to deal with it straight away if it does recur. If that happens, I will report back on this thread.