850 turbo 1996 runs way to rich when cold

alexpia · Post by **alexpia** » 20 Dec 2009, 13:00

hi everyone, im new to this site as a member but i have always used it as a good reference for my volvos. anyway my 1996 850 turbo sedan runs really rich the colder it gets outside after sitting overnight and the temp guage takes a long time to get up to temp(3 0clock). i mean it runs so rich it misfires and i can smell raw gas from the exhaust until it gets to operating temp. it runs fine when the weather is warm but not as good as my identical wagon. ive changed the ect, the iac, the cap plugs wires vacuum elbows,tcv did a compession test got 140 lbs in no 1 cyl and 150 in the other five. does anyone think maybe the thermostat could be staying open causing the computer to think the engine is cold? im a bus mechanic by trade so im not stupid and used to work on cars for a living. this car is driving me nuts. its been like this since i bought it. i havent changed the thermostat for the fear of breaking the bolts plus it 25 degrees right now in connecticut the car has 226000 for miles and isnt in too bad of shape any help would be appreciated. thanks.

Post by **confused_al** » 20 Dec 2009, 13:10

Very likely your t-stat along w/ your ECT need go to retirement home.
https://www.matthewsvolvosite.com/forums ... =1&t=25492

Post by **jblackburn** » 20 Dec 2009, 13:12

I'm thinking you've got a combination of a bad thermostat and a bad coolant temp sensor. The temp sensor reports to the engine computer which adjusts the amount of gas put into the engine, and by nature, it's gonna put in a lot to start it when cold, but it sounds like it's not backing off because it doesn't know what the temperature of the engine is. The same thing caused my car to have (warm) starting problems.

You probably WILL break the bolts getting them off, but its ok, just get the new ones that are steel coated rather than the cheap aluminum ones they put in there.

alexpia · Post by **alexpia** » 20 Dec 2009, 13:30

i changed the ect this summer with an original volvo part but if it has to go it has to go. thanks for the help guys. maybe ill send it over to the next town over from me to eurocars plus and have them change the parts. im pretty friendly with the owner and techs. plus he sells me trade in cars when i need a cheap volvo. happy holidays everyone!!!!

Post by **jblackburn** » 20 Dec 2009, 13:34

I'm suspicious that when the thermostat goes it somehow kills that sensor with it. I'm not sure how, but mine both went at the same time for whatever reason, and it seems like other people's have too.

Happy holidays to you too!

Post by **confused_al** » 20 Dec 2009, 13:54

alexpia wrote:i changed the ect this summer with an original volvo part

If thats the case, replace your t-stat only first and see how your engine runs. The reason I suggested both simply b/c their lifespan is similar.

Post by **marginal** » 20 Dec 2009, 20:09

What is their lifespan?

Thanks.

Post by **jblackburn** » 21 Dec 2009, 08:18

What is their lifespan?

5-7 years? That's about how long they lasted on a Saab we owned for 20 years as I remember. I think mine was still the original in there, and it's 11 years old now.

Post by **confused_al** » 21 Dec 2009, 13:18

I think the average life for those is 8yrs(±4)/100k(±50k). However, its always a good idea replace both at the same time.

alexpia · Post by **alexpia** » 29 Jan 2010, 10:15

i finally was able to get the thermostst changed in my car i soaked the bolts for weeks with penetrating oil and brake fluid. they came right out it took awhile to get the job done cuz it was cold here. anyway no change. the car still runs bad the colder it gets outside it was 30 degrees the other day and it ran ok. but today it is 17 degrees and it ran really bad. it used a quarter of a tank of gas to go five miles. after driving it the five miles and shutting it down for about ten minutes the temp guage still read 3 oclock when i restarted, it ran about 80 percent better and was actually drivable it seema as long as i dont let it sit overnight and completely cool down its ok. other than the ect is there something else that senses the outside temp? what controls the cold start on these cars? my other 96 turbo wagon has 287000 miles and has the same identical engine runs like brand new. the one that runs crappy was hit in the front before i owned it but i dont think that would cause a problem. anymore advice would be helpfull before i have to send it to a garage thanks.