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I have since March 2011 had an intermittent hesitation that is defying my attempts to localize it.
It happens in all weather (though mostly warm) and all operations (idle to 45+).
The last tank of gas it was really bad and mpg dropped from 22 mpg to 17 mpg.
So something would seem to be running rich?
A sensor reading more air than is there?
Something moving too much fuel?
The only component that I know needs work is the Fuel Relay. It is my understanding that if the car starts it is working well enough - I've done the freezer cool down a few times when there was 100 degree weather.
The only other time I have had this symptom was when I was checking the idle on the car and the IAC stopped responding.
Despite the IAC passing all tests including live voltage check of the valve.
I replaced it and the hesitation part of my problems went away.
See below for more extensive list of work done March 2011.
Today:
checked throttle valve switch - Okay
checked for obstructions to air filter - Okay
checked air control valve (IAC) -
hums ... I recall a tapping sound before ...... ? ? ?
... What sound is this unit supposed to make?
... Is the IAC supposed to be lubricated?
AMM (test 3-18-11)
terminals 2 - 3 = (2.6 ohm) [spec is 3.5-4.0] drop from 3 ohm in March 2011
... Does anyone know if a low resistance across these contacts would read as too much air?
terminals 2 - 6 = (363 ohm) [spec is 0 - 1000] same March 2011
terminals 3 - 6 = (366 ohm) [spec is 0 - 1000] same March 2011
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March 2011 I went through some major operations getting the car through emissions.
That work covered most of the things I would be checking now.
cleaned PCV Oil Trap, hoses and Flame Guard
replaced IAC (idle air control) valve w/ new part
replaced Lambdasond (O2 sensor) w/ new part
cleaned Throttle Body including idle control knob
replaced Temperature Sensor
replaced Distributor Cap
replaced Distributor Rotor
More at:
http://www.brickboard.com/RWD/volvo/1481789/220/240/260/280/recap_emissions_failure_repairs_iac_idle_rpm_mpg_pcv.html
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1988 244 DL
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