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850R: Hard warm starts,fan issues, Coolant temp Sensor & more!

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

1992 - 1997 850, 850 R, 850 T5-R, 850 T5, 850 GLT
1997 - 2000 S70, S70 AWD
1997 - 2000 V70, V70 AWD
1997 - 2000 V70-XC
1997 - 2004 C70

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misha
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Re: 850R: Hard warm starts,fan issues, Coolant temp Sensor & more!

Post by misha »

That's what i thought you did....the problem is in soldering.You have higher resistance than it's supposed to be and that's why ecu reports error code for it.
Same case when people used to solder connectors for o2 sensors.

Crimping is better solution.Return everything like it should be and it ect code will disappear...if the rest of the wiring is ok.
'97 850 2.5 20v / fully equipped / Motronic 4.4 from the factory / upgraded with S,V,C,XC70 instrument cluster / polar white wagon
'91 Citroen XM 2.0 SI /fully equipped/mandarine red metallic
History of Volvos in the family:
'71 144 S
'73 144 De Luxe
'78 244 DL
'78 244 DL
'79 244 GLE
'85 340 GLS
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BEJinFbk
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Joined: Sat Jan 05, 2008 10:32 pm
Year and Model: '98 V70 R
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Re: 850R: Hard warm starts,fan issues, Coolant temp Sensor & more!

Post by BEJinFbk »

misha wrote:That's what i thought you did....the problem is in soldering.You have higher resistance than it's supposed to be and that's why ecu reports error code for it.
Same case when people used to solder connectors for o2 sensors.

Crimping is better solution.Return everything like it should be and it ect code will disappear...if the rest of the wiring is ok.
I disagree - A good solder joint should make virtually no difference in resistance.
'98 V70 R - Well Equipped for Life Up North... ;)
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misha
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Re: 850R: Hard warm starts,fan issues, Coolant temp Sensor & more!

Post by misha »

I agree with you on this for most connections.....but ecu is pretty sensitive about resistance differences...and ECT sensor is NOT the one you want to solder wires to.
Every connection have some loss but soldered connection loss is minimal.That minimal is not good enough for ecu.
That said.....if soldering is not performed well,solder joint will have more resistance than acceptable and it would act like there is no solder at all.
I don't get it why crimping is better method than soldering....but for sensors...in practice....crimping shows better results.I also always thought that soldering is the best solution....but again....other's experience show different.
Bosch made crimping set and a box for their O2 sensors because of problems after soldering wires.
'97 850 2.5 20v / fully equipped / Motronic 4.4 from the factory / upgraded with S,V,C,XC70 instrument cluster / polar white wagon
'91 Citroen XM 2.0 SI /fully equipped/mandarine red metallic
History of Volvos in the family:
'71 144 S
'73 144 De Luxe
'78 244 DL
'78 244 DL
'79 244 GLE
'85 340 GLS
bewinder
Posts: 11
Joined: Wed Oct 12, 2016 9:54 pm
Year and Model: 1997 Volvo 850-R
Location: Oregon, USA

Re: 850R: Hard warm starts,fan issues, Coolant temp Sensor & more!

Post by bewinder »

This is interesting... Off to crimping! I'll post soon.
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BEJinFbk
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Re: 850R: Hard warm starts,fan issues, Coolant temp Sensor & more!

Post by BEJinFbk »

But the coolant temp sensor is just a thermistor.
And when these systems get engineered for use
in the field, like an automotive application, they
generally run a pretty wide range of impedance for
a designed temp range just to rule out problems
like sketchy connections.

A bad solder joint would have to be really,
really bad to significantly increase resistance .
I honestly think that a good solder joint with
high quality, hot melt shrink tubing for water-
proofing should be as good or even better than
the OEM weather-pack connector.
You just can't unplug it... :(

Agree to disagree, I guess.
'98 V70 R - Well Equipped for Life Up North... ;)
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misha
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Year and Model: '97 850 2.5 20v
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Re: 850R: Hard warm starts,fan issues, Coolant temp Sensor & more!

Post by misha »

I wonder what could go wrong that brand new Volvo ect is throwing codes and not working as it should?
What could happen is WRONG ect or solder joints.
Can you give us part number of that ect you bought?

Could be that problem is somewhere in the wiring harness.
'97 850 2.5 20v / fully equipped / Motronic 4.4 from the factory / upgraded with S,V,C,XC70 instrument cluster / polar white wagon
'91 Citroen XM 2.0 SI /fully equipped/mandarine red metallic
History of Volvos in the family:
'71 144 S
'73 144 De Luxe
'78 244 DL
'78 244 DL
'79 244 GLE
'85 340 GLS
User avatar
BEJinFbk
Posts: 3757
Joined: Sat Jan 05, 2008 10:32 pm
Year and Model: '98 V70 R
Location: Fairbanks, Alaska
Has thanked: 25 times
Been thanked: 56 times

Re: 850R: Hard warm starts,fan issues, Coolant temp Sensor & more!

Post by BEJinFbk »

I wonder if there's a problem at the ECU connector?
Maybe remove the ECU, inspect the connector and reseat it?
'98 V70 R - Well Equipped for Life Up North... ;)
bewinder
Posts: 11
Joined: Wed Oct 12, 2016 9:54 pm
Year and Model: 1997 Volvo 850-R
Location: Oregon, USA

Re: 850R: Hard warm starts,fan issues, Coolant temp Sensor & more!

Post by bewinder »

Crimped the words going to the ect. No changes. Still getting hardcstarts, fan issues, throttle response issues, flashing arrows. I'm hesitant to continue treating them as isolated problems, especially since they alll started within a few day span...
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misha
Posts: 4513
Joined: Sun Dec 07, 2008 4:09 pm
Year and Model: '97 850 2.5 20v
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Re: 850R: Hard warm starts,fan issues, Coolant temp Sensor & more!

Post by misha »

Time to check some wiring and relays or a visit to a good car electrician.
Iac valve MUST NOT buzzz when engine is off.Something is shorted out.
'97 850 2.5 20v / fully equipped / Motronic 4.4 from the factory / upgraded with S,V,C,XC70 instrument cluster / polar white wagon
'91 Citroen XM 2.0 SI /fully equipped/mandarine red metallic
History of Volvos in the family:
'71 144 S
'73 144 De Luxe
'78 244 DL
'78 244 DL
'79 244 GLE
'85 340 GLS
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