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850 Struggles to Start when Cold

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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E Showell
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Re: 850 Struggles to Start when Cold

Post by E Showell »

Sometimes a bad engine coolant temperature sensor will cause the hard starting issue you describe. Faulty readings will over-enrich the mixture for "cold start" conditions. There is probably a volt/ohm meter test for this kind of thing, but I just replace the sensor.
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Ben850
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Year and Model: 1996 850 R Wagon
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Post by Ben850 »

Check the date on your plug wires. I also had original '93 Bougicord wires still in the car. After new Bougicord wires, Bosch rotor and cap, it is a completely new car.(Bosch Super Copper Plus plugs as well)

You can't go wrong with that combination. Chances are, your '94 may have the identical setup as my '93 if it is NA.
Good Luck.
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rspi
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Post by rspi »

My guess would also be plugs and wires. When was the last tune up?
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slimflex2
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Year and Model: volvo 850 R 1997
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Post by slimflex2 »

E Showell wrote:Sometimes a bad engine coolant temperature sensor will cause the hard starting issue you describe. Faulty readings will over-enrich the mixture for "cold start" conditions. There is probably a volt/ohm meter test for this kind of thing, but I just replace the sensor.
l am 90% this is his problem. Temperature sensor.

Volvofan94
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Post by Volvofan94 »

I'll take another look at the coolant temperature sensor. I visually checked it before, but didn't unplug it from the harness to check the resistance. The needle on the dash works fine. Would a faulty temperature sensor cause the Check Engine light to illuminate?
My guess would also be plugs and wires. When was the last tune up?
The spark plugs and fuel filter were replaced probably a little over a year along with the distributor and rotor. The spark plug wires were replaced last year as well. Cleaned the MAF sensor when I installed a new air filter.

I'll check everything out and post back my findings.
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Volvofan94
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Post by Volvofan94 »

Finally got around to looking at my car. Tested the resistance on the coolant temperature sensor and it registered 6.34 K ohms. From there it rose to a high of 6.37 K ohms (last time I checked). Car hasn't been driven in a few days. Are these normal numbers for the coolant temperature sensor to be reading when ambient air temp is in the mid 30's?

I have a new OEM one on order and will post back the result.

Thanks Everyone! :D
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Volvofan94
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Post by Volvofan94 »

Thought I'd post an update.

The new coolant temperature sensor fixed it.

Very glad to get my car back on the road. Got the opportunity to test it in cold, windy and snowy weather too. It was nice not having to worry if the engine would start in colder weather. :lol:

Thanks everyone for your help; it's running like new again.
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1994 Volvo 850 - 2.3L I5, 160k miles. - SOLD
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slimflex2
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Post by slimflex2 »

Volvofan94 wrote:Thought I'd post an update.

The new coolant temperature sensor fixed it.

Very glad to get my car back on the road. Got the opportunity to test it in cold, windy and snowy weather too. It was nice not having to worry if the engine would start in colder weather. :lol:

Thanks everyone for your help; it's running like new again.
thats good, you are back on the road. cheers

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