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Hesitation at low speed 91 740 wagon 4cyl non turbo 168 km only 700 1991

posted by  someone claiming to be Dans on  Tue Dec 26 16:36 CST 2006 [RELATED]

I've had a hesitation problem with my wagon for the last 2 months.
Replaced the fuel pressure regulator, new air filter, checked the
air mass meter - fuel pump is just 4 yrs old, new fuel filter, & throttle body cleaned, and oil trap cleaned. O2 sensor is 3 yrs old. Car just passed Driveclean with flying colours... also Ran fuel inj cleaner thru 3 tanks,& using 89 Octane with 10 % methanol. (Sunoco)
Car periodically hesitates from start, I think I'm hearing a bit of backfire.
Once up past 40 km / h car runs perfectly. Idles perfectly.



Only thing I did notice was a "hooting" sound from the Idle Air Control Valve line that runs to the air filter - when I pulled the hose off you could hear a periodic "hoot".

Took the IACV off and cleaned it - BUT - is the valve body supposed to be free to float inside the casing? If you shake it should you hear anything moving inside? WHen I took the IACV off and shook it nothing happened & the valve spindle was immovable when I tried to see if it would slide back and forth ...I'm wondering if it's sticking or stuck - I would appreciate it if someone could describe how the IACV is supposed to operate & if there is a test pin on the 740 as there is on the 240 (blue connector on the right above the front wheel?).... Is there a ready source for replacements other than at Volvo in the Toronto area - ie. scrap yards, rebuilds, OEM (bosch?)

Don't hear the hooting at idle after I put the IACV back on the car now.

Are there any tests that you can do to see if the IACV is operating properly?



Thanks & Happy New Year everyone!
Dans in Toronto







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    Hesitation at low speed 91 740 wagon 4cyl non turbo 168 km only 700 1991

    posted by  Herb Goltz on  Wed Dec 27 02:53 CST 2006
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    last visit: Fri Oct 24 13:23 CST 2014
    [RELATED]

    I clean IAC valves by applying 12V and then cleaning with cotton swabs and carb cleaner. Applying voltage is the best way to test the valves-- then you can see if it is working right as well as being able to clean the inner recesses.

    Have you adjusted your throttle position switch as per the 700/900FAQ?

    Good luck!








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    Hesitation at low speed 91 740 wagon 4cyl non turbo 168 km only 700 1991

    posted by  aleekat on  Wed Dec 27 02:12 CST 2006
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    last visit: Fri Oct 24 13:19 CST 2014
    [RELATED]

    You can put 12volts to the center pin, and ground the outer, the valve should slam open and closed as you alternate the ground. The FAQs also covers an ohm test.
    --
    Post Back. That's whats makes this forum work.








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      Hesitation at low speed 91 740 wagon 4cyl non turbo 168 km only 700 1991

      posted by  Herb Goltz on  Wed Dec 27 02:57 CST 2006
      Author: [PROFILE] [EVERY POST] [THREADS] [BEST POSTS] RSS Feed     [IGNORE ALL POSTS]
      last visit: Fri Oct 24 13:23 CST 2014
      [RELATED]

      His idle air valve should be two pin rather than 3-- it's either a -516 or the Rex/Regina equivalent (which seems to be quite a bit more expensive)...

      Cheers!








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        Hesitation at low speed 91 740 wagon 4cyl non turbo 168 km only 700 1991

        posted by  someone claiming to be Dans1 on  Sat Jan 13 13:15 CST 2007 [RELATED]

        It'a the Rex/Regina type, with 2 pins and intake and exhaust connections
        at the end opposite to the electrical connection - I'll pull it again & test it.
        Should the piston slop around freely when u shake it?? I think it was free
        last time I had it out 5 yrs ago. Above idle should there be any air bypassing the
        Throttle body ? or should the ICV completely cut off any airflow through it?
        Regards
        dans







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