Engine 850: B5252S/2.4/10v: - Erratic Idling Fixed !!

damz-850glt · Jun 18th, 2012, 22:44

Hello All...

I had an erratic idle issue (revs rising and falling) on a 1994 850 SE (B5252S 2.5 10v Engine). I read lots of posts and ruled out lots of things and was about to give up when as a last resort I decided to have a look at the Idle Air Valve... (silver thing just in front of the throttle assembly) It looked clean enough and I could move the valve with a screwdriver, so I gave it a clean anyway, but I also gave it a full 12v off the battery to check it was opening and closing, chucked it back in and voila! Engine is runnng sweet again!! So if you've come across this post, give it a go, it costs no money and minimal effort and might just help...

All the best, D.

capt jack · Jun 19th, 2012, 08:44

Yep. That IAV is so dull it's easy to overlook. I've had the same experience.

I first learnt about Air Idle Valves when I owned my 1800ES, which had a temperature-controlled idle air valve. This too had a habit of sticking, and would cause the engine to idle erratically if it would idle from cold at all.

The principle was identical - it's just that the modern equivalent is electrically operated and not directly controlled by the engine coolant temperature as was the original 1960's design!

As you say, it's dead easy to do, costs nothing and works a treat!

Cheers

Jack

v70stu · Jun 19th, 2012, 22:44

Thanks for posting this tip. How exactly do you know it is working? Can you see or hear a click as it opens and closes? I can visually inspect it but just don't quite "get" how it should work. I just need to be sure that mine is actually OK.

Cheers.

phatboy130 · Jun 20th, 2012, 01:10

Also worth giving the linkages on the throttle a good squirt with wd40 every so often, my previous motor, and 850 played up like idle valve, turned out to be dry and sticky throttle linkages, rock steady revs after that

Jun 18th, 2012, 22:44	#1
damz-850glt New Member Last Online: Nov 13th, 2020 13:43 Join Date: Jan 2008 Location: Ipswich View Photos By: damz-850glt	Erratic Idling Fixed !! Hello All... I had an erratic idle issue (revs rising and falling) on a 1994 850 SE (B5252S 2.5 10v Engine). I read lots of posts and ruled out lots of things and was about to give up when as a last resort I decided to have a look at the Idle Air Valve... (silver thing just in front of the throttle assembly) It looked clean enough and I could move the valve with a screwdriver, so I gave it a clean anyway, but I also gave it a full 12v off the battery to check it was opening and closing, chucked it back in and voila! Engine is runnng sweet again!! So if you've come across this post, give it a go, it costs no money and minimal effort and might just help... All the best, D. __________________ Damz. Was - 1993 850 GLT Now - 1997 V70 AWD

Jun 19th, 2012, 22:44	#3
v70stu V60 T6 Last Online: Aug 23rd, 2018 17:01 Join Date: Mar 2006 Location: Leicestershire	Thanks for posting this tip. How exactly do you know it is working? Can you see or hear a click as it opens and closes? I can visually inspect it but just don't quite "get" how it should work. I just need to be sure that mine is actually OK. Cheers. __________________ 2010 V60 T6 AWD, 612 Passion Red,Polestar Optimised, Jetex stainless steel exhaust, ex-Volvo press fleet launch vehicle.

Jun 20th, 2012, 01:10	#4
phatboy130 1999 V70 XT Auto Last Online: Yesterday 18:09 Join Date: Aug 2009 Location: Devon	Also worth giving the linkages on the throttle a good squirt with wd40 every so often, my previous motor, and 850 played up like idle valve, turned out to be dry and sticky throttle linkages, rock steady revs after that __________________ Previous: 740 / 850 / V70 / 440 Current: 1999 V70 XT Auto

Jun 19th, 2012, 08:44	#2
capt jack VOC Member Last Online: Apr 20th, 2024 18:56 Join Date: Jun 2006 Location: Selby, North Yorkshire	Yep. That IAV is so dull it's easy to overlook. I've had the same experience. I first learnt about Air Idle Valves when I owned my 1800ES, which had a temperature-controlled idle air valve. This too had a habit of sticking, and would cause the engine to idle erratically if it would idle from cold at all. The principle was identical - it's just that the modern equivalent is electrically operated and not directly controlled by the engine coolant temperature as was the original 1960's design! As you say, it's dead easy to do, costs nothing and works a treat! Cheers Jack

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