Fast idle

Auldtam · Apr 8th, 2020, 19:40

1998 V70 2.5 10v auto, car idles at 1000 rpm from online research it should idle around 850 rpm. The throttle cable appears to be set correct. The screw below with the spring attached has been marked with a blue marker and the marks are lined up, I expect this has been done by a specialist so didnt want to alter that. Any ideas what might be wrong?

Derek UK · Apr 8th, 2020, 20:06

Vacuum leaks will often raise the idle. Check all of the pipes. Cracks can be hidden on the underside so check carefully.

Luxobarge · Apr 8th, 2020, 22:27

As above. Don't fiddle with the throttle valve or its settings, idle speed is controlled by the idle control valve, if the vacuum leak is bad enough it will simply mean that the idle control valve is closing fully and still can't reduce the idle to the correct value.

When you've found the air leak, idle may take a few minutes to "find" its correct value, as the ECU/Idle control valve have to re-learn a bit.

andrewc1267 · Apr 13th, 2020, 20:32

We have a smoke pro system that fill intake or vac system with pressurized smoke makes finding leaks very fast and simple might be worth a check with your local workshop

Apr 8th, 2020, 19:40	#1
Auldtam Member Last Online: Mar 4th, 2024 14:36 Join Date: Aug 2008 Location: Glasgow	Fast idle 1998 V70 2.5 10v auto, car idles at 1000 rpm from online research it should idle around 850 rpm. The throttle cable appears to be set correct. The screw below with the spring attached has been marked with a blue marker and the marks are lined up, I expect this has been done by a specialist so didnt want to alter that. Any ideas what might be wrong? __________________ Black XC60

Apr 8th, 2020, 22:27	#3
Luxobarge Premier Member Last Online: Today 07:52 Join Date: Jan 2011 Location: Horne (Nr. Horley)	As above. Don't fiddle with the throttle valve or its settings, idle speed is controlled by the idle control valve, if the vacuum leak is bad enough it will simply mean that the idle control valve is closing fully and still can't reduce the idle to the correct value. When you've found the air leak, idle may take a few minutes to "find" its correct value, as the ECU/Idle control valve have to re-learn a bit. __________________ Some people are like Slinkies, they serve no useful purpose but they still bring a smile to your face when you push them downstairs.

Apr 13th, 2020, 20:32	#4
andrewc1267 Master Member Last Online: Mar 11th, 2022 22:01 Join Date: May 2010 Location: manchester	Smoke pro We have a smoke pro system that fill intake or vac system with pressurized smoke makes finding leaks very fast and simple might be worth a check with your local workshop

Apr 8th, 2020, 20:06	#2
Derek UK VOC Member Last Online: May 2nd, 2024 16:48 Join Date: Jul 2006 Location: Chatham	Vacuum leaks will often raise the idle. Check all of the pipes. Cracks can be hidden on the underside so check carefully.

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