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Idle Stalls When Warm

Help, Advice and DIY Tutorials on Volvo's P80 platform cars -- Volvo's 1990s "bread and butter" cars -- powered by the ubiquitous and durable Volvo inline 5-cylinder engine.

1992 - 1997 850, including 850 R, 850 T-5R, 850 T-5, 850 GLT
1997 - 2000 S70, S70 AWD
1997 - 2000 V70, V70 AWD
1997 - 2000 V70-XC
1997 - 2004 C70

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hutch1
Posts: 2
Joined: 10 April 2011
Year and Model: 850, 1995
Location: Virginia, USA

Idle Stalls When Warm

Post by hutch1 »

Greetings!

I have a 95 NA 850 with 190K. Been a good car, but I'm having a reliability issue.

When the engine is cold, the car drives great, and the idle is solid.

However, after the engine warms up, the idle is erratic, stumbles, and the engine stalls. As long as I give it gas, the engine is strong. Only the idle when warm is a problem.

I've cleaned the throttle body and butterfly, but no change.

I'm planning on doing the PCV replacement this weekend, as well as replace the vacuum lines.

What are the odds that this will also fix the warm idle problem? Are there other areas I should look as as well?

I appreciate any additional suggestions!

jblackburn
MVS Moderator
Posts: 14043
Joined: 8 June 2008
Year and Model: 1998 S70 T5
Location: Alexandria, VA
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Post by jblackburn »

Vacuum lines may help. Once the car warms up it goes into closed loop mode and judges readings based on O2 sensor and mass airflow sensor values. Air leaks can throw off the fuel/air mixture and cause your car to run like crap.
'98 S70 T5
2016 Chevy Cruze Premier


A learning experience is one of those things that says, "You know that thing you just did? Don't do that."

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Billc1015
Posts: 192
Joined: 11 August 2011
Year and Model: 1994 855 turbo
Location: Philadelphia Area

Post by Billc1015 »

Have you checked to see if there is any black smoke coming out of the exhaust? It's possible your MAF is on its way out and giving false readings causing a richer mixture. When cold it would run fine because it needs more fuel when vold but after warming up, the extra fuel would cause symptoms like you are explaining.


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