Quote:
Originally Posted by glatt
Yeah. I need to ponder this.
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Demonstrated was why shotgunning does so poorly at eliminating problems. So what has changed? As Gravedigr suggests, collect facts. List every part that was touched (not just moved- touched) when you replaced a filter. What has been touched recently? Not when the intermittent occurred. But even a week previously.
The number of possibilities is literally approaching 1000. No exaggeration. Good diagnostic procedure means reducing that suspect list to more like 100. Which is why replacing the filter only on speculation was so unlikely to be the defect. Especially if blowing in the old filter did not expose a restriction. And since a restricted filter only causes problems on acceleration - not at idle.
Imagine a wire of 32 strands. All are broken. Move that cable and some remain in contact. Move the cable and too many are disconnected causing confusion to the computer or insufficient power to a solenoid. Replace a solenoid. That new one might work with two less strands connected. But the problem still exists. Just fails less often. Only symptoms cured.
Above demonstrates what you are dealing with. Previously listed were how to eliminate some more common suspects (ie EGR valve, vacuum advance and retard system, intermittent manifold leak or defective idle control valve, partially broken cable, dirty connector that gets cleaned by making and breaking and then fails months later because the reason for that corrosion was not identified and eliminated, etc).
Well, one symptom that eliminates some suspects is temperature. Apparently (does?) temperature is unrelated to good and bad operation. Has fuel been eliminated as a suspect - were consecutive tanks from the same station or brand? When the intermittent exists, what exactly do you do to make the problem repeatable or make it worse? Do lights change intensity? Do tires make more noise? Irrelevant is a belief that tires are irrelevant. Solving intermittents means collecting all facts irregardless of whehter you believe it is irrelevant. BTW, that is a repeated concept so accurately expressed in a TV show called House.
I routinely get called when others cannot solve strange problems. Many never learn that this is critically important. Collecting facts and symptoms is completely unrelated to identifying the problem. Which is also irrelevant to what comes later - eliminating the defect.
As I said without exaggeration. Your list of suspects is somewhere approaching 1000. Getting that number down means collecting facts as Gravedigr noted. And then identify a defect long before replacing any parts. Yes, even strange noise from tires in rare cases can be the kicker that identifies an intermittent engine problem.