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This is a 1991 240 station wagon with 110,000 miles, A/C, and auto trans.
While driving at freeway speeds and on city streets (in other words, at all times), I notice a brief (fraction of a second) slowing down of the car, similar to driving on a windy day or in a cross wind. It has become more frequent and more pronounced over the last six months. I do not notice it when under power.
My first question is whether this fits the definition of "hesitation", or if this is called something else
The impression I have is that something is giving faulty input to the computer telling it to do this.
I ran the on board diagnostics in the fuel injection part of the Bentley manual, and all was normal
I know that there could be any number of things that I should check.
However, I am hoping that this observation points to one or two likely causes.
Other than this, the car seems to run fine. Well, the idle is not as smooth as I think it should be.
Second question. Could the fuel pump relay be intermittently and briefly not operating properly?
Could the fuse under the hood for the fuel injection be going bad?
(Both of these were replaced a few years ago after being towed to a shop when the engine quit)
Listed here are procedures I could perform, or that I already have performed. I would be interested in knowing in what order to perform these, that is, in the order of their likelihood to be causing the problem.
- Replace cap and rotor (done - no improvement)
- Turn off A/C (done – no improvement)
- Clean air mass meter (AMM)
- Replace AMM
- Remove and clean throttle body
- Check/test crank position sensor
- Replace oxygen sensor
- Do nothing more until it gets worse
- Take to qualified Volvo mechanic
Thanks in advance for any direction you may suggest.
FAOF2
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