Volvo RWD 900 Forum

INDEX FOR 10/2025(CURRENT) INDEX FOR 11/2023 900 INDEX

[<<]  [>>]


THREADED THREADED EXPANDED FLAT PRINT ALL
MESSAGES IN THIS THREAD




  REPLY TO THIS MESSAGE Replies to this message will be emailed.    PRINT   SAVE 

Air Mass Meter 900 1997

posted by  my960 on  Wed Apr 28 07:04 CST 2004
Author: [PROFILE] [EVERY POST] [THREADS] [BEST POSTS] RSS Feed     [IGNORE ALL POSTS] [RELATED]

What are they and what control do they have over the engine?








  •   REPLY TO THIS MESSAGE    PRINT   SAVE 

    Air Mass Meter 900 1997

    posted by  DanR on  Wed Apr 28 14:59 CST 2004
    Author: [PROFILE] [EVERY POST] [THREADS] [BEST POSTS] RSS Feed     [IGNORE ALL POSTS]
    last visit: Thu Oct 23 15:25 CST 2014
    [RELATED]

    The air mass meter measures the density of the air. Which then is calculated thru the ecm for the proper amount of fuel to make the perfect burn. When the perfect burn happens, which it never does, but on paper any way, the burn makes water vapor and carbon dioxide. Since that never happens especially in a car engine we need all these other things to get it somewhat close to perfect.

    The black smoke could be that the fuel pressure regulator is bad, making the car run rich. It could just be soot built up in the exhaust system, then every once in a while you push the gas pedal to the floor and all of the crud is blown out. Another possibility that I can think of, is that your flame trap is in need of maintence, this can cause oil to accumulate in the bottom of the intake manifold, when that oil warms up and gets a little fluidy, the sudden rush of air when the pedal is floored can cause some of that oil to be ingested, hence the smoke. You don't state any mileage or maintence records so these are just guesses.

    Some of this rambling is from my observations with my own car, and may be contradicted by those who are much more knowledgeable than me.

    DanR 94 964 249,000 miles (15,000 on the new engine)
    --
    DanR








  •   REPLY TO THIS MESSAGE    PRINT   SAVE 

    Air Mass Meter 900 1997

    posted by  someone claiming to be tjts1 on  Wed Apr 28 07:24 CST 2004 [RELATED]

    it gives the engine computer a rough estimate of the ammount of air going into the engine. It allows the computer to regulate the ammount of fuel to feed the engine at any given time. The O2 sensor does the dirty work of keeping to air fuel ratil at exaclly 14.7 to one.








    •   REPLY TO THIS MESSAGE    PRINT   SAVE 

      Air Mass Meter 900 1997

      posted by  ian f. on  Wed Apr 28 11:59 CST 2004
      Author: [PROFILE] [EVERY POST] [THREADS] [BEST POSTS] RSS Feed     [IGNORE ALL POSTS]
      last visit: Sun Jan 30 15:23 CST 2011
      [RELATED]

      So if I stomp on the accelerator at highway speeds and get a plume of black smoke, is the AMM bad or is the O2 sensor bad?








      •   REPLY TO THIS MESSAGE    PRINT   SAVE 

        Air Mass Meter 900 1997

        posted by  someone claiming to be tjts1 on  Wed Apr 28 12:44 CST 2004 [RELATED]

        If you are flooring it or are using more than 80% throttle, the engine goes on what is refered to open loop. This means it no longer uses the signal from the O2 sensor to fine tune the AF ratio. It relies only on the AMM and a series of air fuel ratio maps. The AF ratio is reduced to something around 13 to 1 where the engine produces the most power but the exaust is less clean. Even so the engine should not be smoking. The AMM can be one of several components gone wrong. Does the engine still produce adaquite power at full throttle? If it does I would rule out the AMM. I would suspect the injectors but that's just guessing. A more expensive possiblity could be the piston rings. At full throttle the rings are being expost to the maximum stress. A compression check at a mechanic can answer that question.
        Are there any other unusual symptoms? How many miles does the car have? How often has the oil been changed? Did you use synthetic?
        Justin
        94 965








        •   REPLY TO THIS MESSAGE Replies to this message will be emailed.    PRINT   SAVE 

          Air Mass Meter 900 1997

          posted by  ian f. on  Thu Apr 29 13:23 CST 2004
          Author: [PROFILE] [EVERY POST] [THREADS] [BEST POSTS] RSS Feed     [IGNORE ALL POSTS]
          last visit: Sun Jan 30 15:23 CST 2011
          [RELATED]

          The engine remains strong at full throttle. The car was well maintained and oil appears to have been changed regularly, but I have no idea if they used dino or synthetic.

          Why do you suspect the injectors and is there any way to test them?

          I could do a compression check, but if I am only seeing black smoke at full throttle, would a compression check at idle necessarly tell me anything?

          TIA,
          Ian








          •   REPLY TO THIS MESSAGE    PRINT   SAVE 

            Air Mass Meter 900 1997

            posted by  someone claiming to be sredwine on  Fri Apr 30 06:41 CST 2004 [RELATED]

            Ian,what is the mileage on the engine (both odometer and fuel usage)?Rich conditions will lower your gas mileage.It's possible if the car was never driven hard that carbon build-up has ocurred in the cylinders.Push it hard a bit or do the Italian tuneup (see 700/900 FAQ under features) to see if it clears up.
            sredwine '98 V90 has 77K,'94 944T has 145K








            •   REPLY TO THIS MESSAGE Replies to this message will be emailed.    PRINT   SAVE 

              Air Mass Meter 900 1997

              posted by  ian f. on  Fri Apr 30 08:01 CST 2004
              Author: [PROFILE] [EVERY POST] [THREADS] [BEST POSTS] RSS Feed     [IGNORE ALL POSTS]
              last visit: Sun Jan 30 15:23 CST 2011
              [RELATED]

              The car has 160,000 miles and get around 21 mpg which is consistent with what I got on my 88 745t and 87 745t.

              Will try the italian tuneup tonight.








  •   REPLY TO THIS MESSAGE    PRINT   SAVE 

    Air Mass Meter 900 1997

    posted by  someone claiming to be bcrazy on  Wed Apr 28 07:13 CST 2004 [RELATED]

    it measures how much air is entering the engine. So that the ecu can give right amount of fuel.







<< < > >>



©Jarrod Stenberg 1997-2022. All material except where indicated.


All participants agree to these terms.

Brickboard.com is not affiliated with nor sponsored by AB Volvo, Volvo Car Corporation, Volvo Cars of North America, Inc. or Ford Motor Company. Brickboard.com is a Volvo owner/enthusiast site, similar to a club, and does not intend to pose as an official Volvo site. The official Volvo site can be found here.