Car question

[BigV]

Originally Posted by tw

That is the point. You do not understand the relevance. Do not understand how that information results in solutions.

right, RIGHT. Exactly. Now, at last, you understand my question. Of what possible relevance is gas mileage measurement fixing a rough idle?

Originally Posted by tw

Solve problems in two steps. First collect facts. Much later solve the problem.

You have some facts. You don't have all the facts. You'll never have all the facts until the problem's solved.

Originally Posted by tw

Some of that stuff posted fix a problem without first determining what is wrong is called shotgunning. Could even exponentially complicate his problem. Those was some of the most random and irrelevant wild speculation I have read in a long time.

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

Originally Posted by tw

Any mechanic that did that would have been quickly unemployed. You should have been mocked for those consecutive and irrelevant recommendations.

Well, he's not taking it to a mechanic, he's asking us, asking me. I think a mechanic that did the things I suggested would be employed far longer than a mechanic that did the things you suggested. Just curious, what part of my recommendations do you consider irrelevant?

Originally Posted by tw

But then making all those mistakes is how we eventually learn. I just ignored them suspecting that glatt also would probably be doing same.

Embarrassing was a claim that two cylinders fire simultaneously.

Cite. An even firing sequence is pretty common, anything else is unusual for an inline four.

Originally Posted by tw

And a few other bogus claims.

Cite.

Originally Posted by tw

Each cylinder fires separately.

Cite.

Originally Posted by tw

You should have known that since it was taught even in primary school science. No reason to mention that until now that you decided to entertain your ego. I was not going to say anything then. But now you need to learn some humility. Big time.

Buddy, I've been sayin that from the beginning. If you have something to teach me, bring it on. To this point you have not been forthcoming. I've asked you and asked you for your explanations, only to be be met with silence and bloviation in equal measure. You have some mechanical explanations for what's happening here, I'm interested in learning them, humbly. I'm still waiting...

Originally Posted by tw

We have a list of suspects from the shop manual. And a few others not on that list. Facts such as diagnostic codes, information collected by a portable computer from the dealer, and gasoline mileage all provide relevant information. Facts to significantly reduce a list of suspects to but a few. Even the fact that roughness did not correspond to an engine code was useful information.

Sure. We have some facts, ok, I agree. Now what do you suggest to do with the facts you have?

Originally Posted by tw

Also important are conditions that cause or co-exist when roughness does and does not exist. Whereas tire pressure likely is not relevant, it is still a change that should known. Never short the help of a change only because you consider it random or irrelevant.

I short the help of a change (???) when it a distracting obfuscation. Like gas mileage. You do know that the gas mileage of his car when idling is zero, right?

Originally Posted by tw

Use the oxygen sensor as an example. Some assumed an oxygen sensor could cause rough idle. Why? An oxygen sensor is mostly about operation at high speed; not at idle. An oxygen sensor (in most designs) has no influence on how idle works. Why then did someone suspect an oxygen sensor? An example of implementing a solution long before a defect was even defined.

Gasoline mileage goes a long way to exonerating many suspects.

Really?? For a rough idle? HOW? How? That is my question, how does knowing the mileage fix the rough idle? It doesn't man. You might have posed a better question by asking how the mileage has changed. But even then you would have gotten a small range of answers, same, better, worse, LOTS better, LOTS worse, all over the place, stuff like that. But even knowing which of those answers was the "fact" leaves you with no suggestion as to what to *DO*.

Originally Posted by tw

But not everyone would understand that for a same reason why some might automatically suspect an oxygen sensor.

Another example was recommended. Full to the floorboard acceleration repeated after each engine restart. So that diagnostic codes might report some other defects. It should have been done especially when one has no idea what that will discover. What was to you random was actually targeting specific suspects.

You have no idea why gasoline mileage numbers were important.

If you do, please tell me.

Originally Posted by tw

Numbers more useful had those numbers been taken when the car was running better. Numbers that would have even said more if taken for a tank of Liberty and another tank of Shell.

Moving on. Another explained what high octane gas is. It is not cleaner or better. High octane does not burn out crud. It is only different. Some brands include additives that make other differences.

For example, Mobil once contained high detergent additives. Therefore gas was cleaner? No deposits? Nope. High detergent levels in Mobil caused increased carbon deposits on valve stems.

Same applies to high octane. High octane can increase engine wear and failure on some parts. The word high does not mean better (except at the end of the day in a room with a towel covering that hole underneath the door).

So, based on what facts we all know, what do you think could be the reason for the rough idle and what do you suggest to resolve that symptom?

[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?

[Pete Zicato]

Originally Posted by BigV

So, based on what facts we all know, what do you think could be the reason for the rough idle and what do you suggest to resolve that symptom?

Trying to get a straight answer from TW is like trying to nail jelly to a tree, innit?

[Lamplighter]

Someone drove the car until the gas was very low, and/or
the gas cap was not put on tightly so the check engine light came on.

Full tank of fresh gas + tight cap + running engine 30+ minutes => light goes out = problem solved.
.