Car question

[tw]

Originally Posted by BigV

No, it's not called shotgunning. It's called an iterative process, a process of elimination.

What was posted was classic shotgunning. As I said before, a major reason for fixing things is to learn. Eventually you may learn that those long posts were classic examples of shotgunning. You were even trying to fix things that were not relevant to his symptoms. Trying to fix things base upon "it might be this so do that". That is shotgunning.

Some of your suggestions would fix things not even relevant to the symptoms. Understandable because even some basic concepts, essential to auto repair, were unknown. A firing order for a four cylinder engine is typically 1, 3, 2, 4. Two cylinders do not fire simultaneously. That would cause imbalances. Explains many suggested actions that were irrelevant. Shotgunning often happens when underlying concepts are not first learned. Again, cylinders do not fire simultaneously.

what do you think could be the reason for the rough idle and what do you suggest to resolve that symptom?

Exactly the point. Once never cures symptoms. Symptoms are part of the process of identifying a defect. Fix defects; not symptoms. First identify the problem. Fixing comes much later. Shotgunning is suspecting and then fixing things when one has not a clue.

In an example, you asked how gas mileage fixes rough idle. Again, fixig comes later. Gas mileage is the process of first identifying the defect. Using gas mileage to fix roughness is an example of 'shotgunning'.

Based upon facts, a defect is not yet identified. A long list of suspects exist. Many might be eliminated with better knowledge, labor, or equipment. Ie. remove a suspect to test it on the bench. But that would take time, more posts, and sometimes creates new problems. Instead, use better knowledge, for example, to know an O2 sensor is an unlikely suspect (based upon symptoms provided).

No rush. The car still works. Plenty of time to identify the problem.

Facts provided a reduced suspect list - posted earlier. Still too many. Listed was how to obtain more facts since even mileage numbers could reduce that list. Mileage numbers are still too subjective.

However if you know more, then define what will identify or exonerate each suspect. The list is there. If you know more, then detail how to identify the defect from that suspect list.

Other relevant questions were asked such as behavior at various RPMs and temperatures, changes after Liberty gas has been fully displaced by regular Shell, operation so that engine diagnostics can see some problems, and using an onboard computer to monitor engine parameters when roughness does and does not happen.

In thinking back, I don't remember. Another of many still unanswered questions. Were spark plugs and wires changed a few thousand miles before this roughness started?