Idle problem

Pcar · Post by **Pcar** » 13 Feb 2011, 16:55

Hi ,great site , just did my front pads with your help and the hardest part was taking the wheel off . Thanks very much.
I have a 1999 xc70 that has developed an idle problem. When the engine is warm the idle will pulse up and down about 200 to 500 rpm a second , this only happens in park or neutral or when the car is coasting slowly. It does not do it when waiting at a stoplight in drive. Other than that it accelerates and drives as good as ever. Can anyone suggest where to start replacing parts.
Thanks, Mike

Post by **vjaneczko** » 13 Feb 2011, 17:29

First, welcome to the forum.

Second, you may not have to replace parts. Pull the MAF connector as the car is running. If the idle improves a bit, clean your MAF. Other things to check/clean; idle control valve and throttle body.

How many KM on it? What kind of service history does it have? You may want to do a stage 0 if it's been a while for those bits.

Pcar · Post by **Pcar** » 15 Feb 2011, 09:36

Thanks for the advice ,will try those items first.

Pcar · Post by **Pcar** » 15 Feb 2011, 17:54

I unplugged the MAF and the idle got worse ( very rough and slower so I quickly put it back in ) the car seemed to idle worse than it did before I unplugged it. I'll clean the MAF tomorrow anyway and see if that helps. By the way the car has 148k and has a spotty service history as it did alot of sitting from 2005-2008.

Post by **vjaneczko** » 15 Feb 2011, 21:34

Sounds like the MAF is OK but cleaning it is never a bad thing. Have you checked for some codes?

If it's been sitting for a good amount of time, you might want to read this and see how many tasks you can check off:
https://www.matthewsvolvosite.com/2009/0 ... s-stage-0/

Pcar · Post by **Pcar** » 19 Feb 2011, 19:58

Cleaned the MAF and the problem still remains. I'll go over the stage 0 and think about cleaning the throttle body soon.
Thanks for your help.

Pcar · Post by **Pcar** » 02 Mar 2011, 13:23

Success !!! I have a '99 xc70 that had an erratic idle for the past 3 months. Sometimes as much as 1000 rpm variation in park or neutral once the car was warmed up . Did a tune up ,cleaned the MAF to no avail . Took it to Volvo and they said a new throttle body ( $1200 ) was needed. So I took it to an independent to have my throttle cleaned as suggested by vjanczko. The car now purrs like a kitten and the idle is as stable as a rock. Thank you all who made suggestions . You saved me a $1000. And now a warning to all those like me who are new to this site. Do your research , ask questions and try all the simple inexpensive suggestions first. Members of this forum have been very gracious with there advice and I really appreciate it. The irony is if I had taken Volvos word for it and changed my throttle body ,it would have fixed the problem and they would have said " We were right, you did need a new throttle body" , when all it needed was a cleaning.

Thanks again , Mike