hello everyone, i have a 1995 2litre 20valve volvo 850 non turbo version.
i'm told you can fit a resistor to the plug of the intake air temperature sensor which is supposed to increase power. all i can seem to find on the air intake ducting is a mass air flow sensor with four wires attached to it.
is this sensor a multifunction unit?
do i have an intake temp sensor on my car?
every other motor iv'e looked at as in ford and vauxhall etc seem to have a two wired probe in the air ducting except mine.
any help welcome.

 

I think there may be a terminology problem here.

There is a thermostat in the air intake box on normally aspirated cars that directs air flow from cold (from the front of the car) to hot (from a shroud around the exhaust pipes). Each and every one of them that was ever sold has failed and, unless it was replaced or defeated, is forcing hot air into the intake at all times.

One clue is the condition of your air filter. If, after 6 months it is still very clean the thermostat is shot.

Other symptoms are low power and excessive fuel consumption.

Here is a thread that discusses it and, about half way through is a method of forever defeating it. The car doesn't care except that it takes perhaps another 1/4 mile to reach full operating temperature on the coldest day.

http://www.matthewsvolvosite.com/cha...pic.php?t=8830

...Lee

 

Lee,

If I am looking at all this correctly, that damper helps in two ways. It redirects unburned fuel/air mixture back into the combustion chamber to get burned up before the engine is running optimally(warmed up). If this doesnt take place, the catalyst in the converter can overheat/bake and mess up, needing replacement.O2 sensors may get messed up, but unlikely i believe.

for anyone needing to get emissions tested, just make sure you warm up the car first. If not, you probably wont pass the test!

 

That would be the EGR circuit. All the air box thermostat does is redirect warmer air to the intake - theoretically - until the engine warms up. It is a lot like the dampers on a Ford or a Chevy that draws air off of the exhaust manifold until the car warms up back on the carburetor engines. (the hose that comes off of the passengers side manifold to a damper in the air intake snorkel).

All that the thermostat does is draw intake air over the warmer than ambient exhaust system, it doesn't actually do anything with what is coming out of the pipe.

The real downside is that the intake air temp sensor is located on the snorkel to the intake side of the airbox and the ECU is making decisions based on that temperature rather than the hundreds of degrees hotter exhaust system air temperature.

The net result is a much richer mix which means crappy mileage and reduced performance.

As far as emission tests go, I have no clue. Thank God, at least for now, in my part of the world we don't deal with that crap.

Off topic on: We used to have a SAE sanctioned "Safety inspection" for plate renewals which was the service stations (They existed then) bill of rights to steal. A lot of muffler bearings were sold. I can vividly remember getting busted by the cops on the way to get my plates on my '69 AMX with my left hand out of the window holding the windshield in place with my hand. The cops first question was , "who in the he** inspected this car?".

Off topic off,

...Lee

 

well, unless there are holes in that metal tubing from the manifold to the intake hot air inlet, it has to be sucking in exhaust fumes which equate it to doubling up what an egr valve does...sorta. if that is not the case, then there is no other place for the O2 to come from...it just doesnt make sense the way you are describing it...

 

The hot air that Lee is talking about is not the exhaust gas itself. There is a shroud above the exhaust manifold air is pulled over the hot exhaust manifold heated and then passed into the air box when the flap is open. When the flap is closed air enters from the front of the car.
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ok, thanks for the clarification...either way, Lee was correct. The thermostat was in the Closed/HOT position when it should have been open/cold. wish i had my cameraphone with me to show the EASY way I kept it open. probably costs about $0.50 at a hardware store or better yet, found in your garage/toolbox like I found in mine.

 

I love all of these tips. My car has been smelling hot. Not real hot but I can hear a thermostat sound like its struggling, plus it has that hot smell. Guage is at halfway, but it does not fluxcuiate. I say thermostat! But the post about the air cleaner thermo going haywire also alarmed me. Well with advice I got a saw and made two pine dowels, and stuck them in to open the cold air vent. Lord knows I need every bandaid I can get right now. I put the thermo in the freezer but no change. I'll drive it tomorrow.

 

I can tell driving today with the cold air vent open is bringing this car back to life. Sweet fix. On another note, I took the thermostat off that was saying "hey it's stuck open kinda making a weird gargling hissing sound," sure enough the rivets or brass presses had come loose inside causing it to just work half ***. No more hot smell and is back up to par.

 

Boy am I glad I came across this thread, thanks to all that posted comments, solutions and links in regards to the air redirecting valve. I had been wondering why my car would warm up so quickly (about 200 yds or so) After reading this post (which started differently) and going through the Matt's link, I found that my air box has been feeding hot air this entire time.

After a quick fix with a screw and a small hole I made an adjustable wedge that will keep it open (and close shut the hot air side) which I can manually undo in the winter when it gets really cold.

I also foud that the vacuum unit doesnt shut the hot air side completely and leaves it hanging 1/2 open, but when I apply vacuum to the motor it shuts the cold side very well, which is what has been affecting my car's performance and fuel economy.

what I have to wonder is why this is not covered in the stage "0" posts that I have read, it seems to be something that needs attention and should be checked on a regular basis, especially cleaning that vacuum motor that is subject to all the garbage that flows by it and gets caught in the spring assembly and makes it fail like mine has.

Anyway, thanks again.

 

Probably because most around here are turbo guys (turbo cars don't have this); they don't really care about us N/A folks...

 

I can't speak for everyone with a turbo but I know I keep an eye in my rear view mirror to make sure you guys are still there

 

See, that's what I'm talkin about! No friggin respect..

 

LOL, yeah I guess, but I bet in the long run N/As get better MPG

 

maybe, but us Turbo owners have more fun, and more power