Idle Speed Motor ***SPLIT from Liner Seals***

[Ron]

UGH! I despise the tetrahedron model!

If the values of the individual components are sufficient enough to induce oxidation, that in and of itself should be considered the chain reaction which completes the triangle to cause a fire. Otherwise, you ain't got no fire! The tetrahedron model completely ignores the individual values of the contributing components and acts as if the chain reaction phase is itself some sort of magical primer that initiates the entire thing, instead of actually being the end product of fire. Likewise extinguishing any blaze isn't simply stopping the chain reaction by itself, but removing one of the three components by removing one or more of them from the chemical reaction.

I feel like the tetrahedron model was nothing more than trying to make fire safety more "hip".

LOL...I've heard that before and I see where you are coming from. If you view fire as a thing, at a given moment in time, rather than as an event, it makes sense.

Another way: The triangle 'theory' states that given the three things in sufficient quantities, you WILL have fire. If you add halon, for example, there will be no fire although the three are still present in the same quantities. Contradiction.

[DMCVegas]

As promised:
Attachment 61865

I can agreed on all...assuming you agree we do have enough already to determine if there is a vacuum leak w/o individual MAP sensors, just not where it is coming from (can't be the areas defined so far, since they are measured). Maybe we need to make some more assumptions, for now, to avoid the can(s) of worms. Expanding with the same example, a perfect stock engine with a perfect setup could have a high A/F caused by a fuel system leak getting into the air intake....endless rabbit holes going to China.

I agree. Looking at the engine as-is in pure stock form, we have the visual error of a hunting idle speed that deviates more than 50 RPMs from the mean, which manifests itself as continued severe looping in speeds.

Absolutely we could have a high A/F ratio due to a malfunctioning fuel delivery system that could cause this same symptom. If it were an external vacuum leak, then we could proceed with the traditional smoke test, or just go right for the throat and spritz starting fluid or carb cleaner around various parts of the intake system to observe a jump in RPMs. Wherever we spray and get the surge, that's where we've found our leak.

Now if it were an issue of an unmetered fuel system leak, we'd have both the idle issue, as well as stumbling. It is at that point we might start with leak down tests, as well as visual inspections and mechanical testing of the system as a whole, and the individual components. Spray patterns, popping pressures, injector flow rates, distributor flow rates, etc.

Tests that may even need to be performed with modern OBD-II EFI systems. The only difference here is we're observing physical symptoms as the warnings, and not the glow of an idiot light.

[DMCVegas]

LOL...I've heard that before and I see where you are coming from. If you view fire as a thing, at a given moment in time, rather than as an event, it makes sense.

Another way: The triangle 'theory' states that given the three things in sufficient quantities, you WILL have fire. If you add halon, for example, there will be no fire although the three are still present in the same quantities. Contradiction.

It is matter of perception though, I suppose. The triangle is the rule of thumb, but in order to complete a triangle geometrically, no matter which type, all three sides must be touching. Much akin to how dropping a lit match into a full jerrycan will simply extinguish the match since the fuel smothers it, but a jerrycan full of fumes will result in ignition. In the prior example, not all 3 sides touch as the heat is disbursed and the flame is smothered. In the latter, all 3 sides touch at once, and fire.

I also understand how use of the chain reaction within the tetrahedron model helps to also explain smoldering. But still, even then I don't believe it to be apropos as it also leaves out other factors. Granted we can even challenge the validity of the fire triangle at this point as well. In the end, I just feel that the 4th side obfuscates the safety factor for the layperson. If people could be trusted to better understand fire, or matters of safety in general, we wouldn't have to teach people mantras or jingles to keep them safe.

[David T]

Things like the fire triangle and such are useful simplifications to get a quick handle on a situation. Like ABC for first responder EMT's. Easy to remember like the food pyramid. Not completely accurate but covers most situations. As for "hunting", with several control systems that are not talking to each other except through the thing they actually control, they each have their own hysteresis causing the idle to go up and down as they interact with each other. That is why there is the + - 50 RPM. Add vacuum leaks and that reduces the range (power) the idle system has over control of the system. Now add worn tired parts and bad electrical connections and then the systems lose what little control they had.