TBI problems, running rich

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texas tough

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I apologize if taking this down the geek rabbit hole - but you started it! ;)
I know a bit about control systems - ie. things that use feedback of something to control something to a target. eg. missile targeting, cruise control, and I assume this feedback loop controlling the TBI AFR.

You're right about the source of the terminology. Control systems can be of different "order" which means they use more info from the feedback signal(s). You can control something just with the difference between target and actual. You can do better controlling something with the difference between target and actual + the rate of change. You could also incorporate the 2nd derivative for even better performance.

A first order control system uses the first derivative of the signal. In a control system, this means the system contains an integrator (essentially the math which does the derivative and determines the correction needed).

The BLM block learn multiplier is not familiar to me but a "block diagram" is used as term to describe a control system diagram/design. So I'd guess the BLM is the steady state error or offset correction needed for the various AFR control cells. For example, the steady state fuel requirements @ high RPM/cruising is larger than at idle. When control system changes cells it uses that steady state value as "center point" and then zeros in to target A/F - seems like by watching Int and if it rails tweaking the BLM center. All this is a guess but how I think about the system.

a bit technical but may be interesting https://www.electrical4u.com/first-order-control-system/
from that article:
In a closed-loop control system, the system has the ability to check how far the actual output deviates from the desired output (as the time approaches infinity, this difference is known as the steady state error). It passes this difference as feedback to the controller who controls the system. The controller will adjust its control of the system based on this feedback.

..... We have two types of systems, first-order system, and second-order system, which are representative of many physical systems.

The first order of the system is defined as the first derivative with respect to time and the second-order of the system is the second derivative with respect to time.

A first-order system is a system that has one integrator. As the number of orders increases, the number of integrators in a system also increases. Mathematically, it is the first derivative of a given function with respect to time.
the system is continually attempting to achieve stoicometric efficiency within the parameters that the engine is operating in., the parameters change constantly due the barometric pressure changes , fuel octane, load, humidity , driving habits,, yes driving habits,,, more on this later... ect.. think of it as an adaptive learning system. The O2 sensor oscillates very rapidly on these trucks, as combustion gasses pass by it. its not sniffing anything, it is reactive to temperture changes. it is basically a thermistor that changes resistance with changes in temperture. these variations in resistance are continually sent to the ECM and the ECM makes adjustment to the timing and injector pulse width once the truck goes into closed loop. a truck that idles fine for a while then starts surging is usually in a "confused" state.. many times when a truck senses a lean condition, this looping surge will manifest... the coolant temp sensor is signalling the ECM that the truck is warmed up but the O2 sensor sees a continuous lean condition.,,. so the ECM tries to make adjustments in the timing and fuel for a while. when it cannot bring the engine in to acceptable parameters, it defaults back to open loop base timing and fuel trims..
The knock sensor actually detects pre ignition and detonation and will signal the computer to make changes if it picks up too many knocks.. the knock sensor picks up vibrations and you can actually test it by knocking on the block near the sensor with a metal pipe .. !! a good OBD1 scanner will show knock counts.
the system is quite high tech in some ways and crude in other ways. the system also adapts the transmission parameter according to how the truck is driven. it will modify shift points to have a "memory" of your driving habits.. if you let someone else drive your truck for a week, when you get it back, it may feel different in its shifting. if you like to just ease on thru the shifts, in a tame relaxed way, and the person u loaned the truck to like to get to 3rd or 4th gear real quick, the truck will block learn these driving habits.
I drive very mildly "most of the time" . and my truck shifts very softly. like a caddy.. if I start driving aggressively for a while, I can feel the shift points change. the computer lets the rpms go up a bit before it lets it shift. it kind of puts it in a performance mode so to speak. many people arent aware that these trucks will do this. even some transmission rebuilders. drive your truck like you stole it for a few cycles, and you will notice what ive said. then drive it like your hauling eggs, and see the change. I can feel the changes very profoundly after Ive towed my boat then unhook the trailer and go for a spin, the truck feels riled up, and the shifting is more crisp and aggressive.

this technology is used in many things, such as refrigerators.. some have adaptive defrost control. the system times how long it took for the previous defrost cycle, by measuring when the defrost thermostat came on and went off. if the thermostat came on and off in lets say 10 minutes, the next call for defrost will be TIMED to last maybe 10 or 11 minutes. if the defrost theromstat on the next defrost cycle takes 15 minutes, the next TIMED potential defrost session will be set to 15 minutes.. the reason is so that the fridge is not keeping the compressor off for longer than needed and can get the temp down to where it needs to be quicker.
 

Schurkey

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The O2 sensor is reacting to the level of O2 in the exhaust, compared to a sample of "outside air" generally supplied by the amount of air included in the O2 sensor wire harness, between conductor and plastic insulation.

It's NOT a thermistor; and it's NOT reacting to "temperature".

Wikipedia has a reasonable explanation of O2 sensor construction differences and operation

Similarly, the non-"E" transmissions have no computer compensation for shift quality/operator characteristics. A 700R-4 or 4L60 has no computer compensation. A 4L60E, for example, does.
 
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