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94' 850 Slightly Rough Idle when cool outside

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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stheis
Posts: 15
Joined: 7 April 2013
Year and Model: 94 850
Location:

94' 850 Slightly Rough Idle when cool outside

Post by stheis »

I've noticed when it's cool outside in the morning, maybe about below 60*F or so, the idle in the car is just a little rough, bouncing around a bit. Doesn't seem to be a big deal, but maybe it's something I can nab early before it's a problem. Anyone had this and figured it out? Thanks again, you guys are awesome!

Ozark Lee
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Post by Ozark Lee »

Have you read the codes? If this is a turbo they will all be read in port A-2. On a Non Turbo they can be split up between ports A-2 and A-6.

...Lee
'94 850 N/A 5 speed
'96 Platinum Edition Turbo
Previous:
1999 V70XC - Nautic Blue - Totaled while parked.
1999 V70XC - RIP - Wrecked Parts Car.
1998 S70 T5
1996 850 N/A
1989 740 GLT
1986 740 GLT
1972 142 Grand Luxe

jblackburn
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Post by jblackburn »

Temp sensor comes to mind, but start with codes first, if there are any.

If not, test the resistance at the temperature sensor by the thermostat on a cool engine.

* -20C: 16,000 Ohms (16 kOhms)
* 0C: 7,300 Ohms
* 20C: 2,600 Ohms
* 80C: 300 Ohms
* 90C (Operating Temp): 200 Ohms
* 100C: 150 Ohms
'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."

mercuic: Long live the tractor motor!

stheis
Posts: 15
Joined: 7 April 2013
Year and Model: 94 850
Location:

Post by stheis »

thanks guys, I'll check those options when I have some time but will be a little busy for the next week. I believe it's had that idle issue since I've had it (about 8 months) and I had checked for codes a couple months ago and didn't have any so might be more likely the temp sensor.

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