If the O2 reading is low is that rich or lean?
Also if the Right and Left BLM's and Intergrator are above 128 is that rich or lean over time?

Thanks.

 

High O2 mV values mean rich, low O2 values mean lean. The stock O2 sensors are not good predictors of true air fuel ratio as they are narrow band sensors and are only accurate in a very small range (centered around 14.7 afr).

From the ScanMaster instructions:

LBL/RBL (Left Block Learn/Right Block Learn):

Here's where your ScanMaster is going to tell you a lot more…. You just have to know how to find it.

When the PCM misses on the fuel calculation, it attempts to correct the condition by using the "Integrators". But, often this isn't enough. If the PCM sees that the Integrators are always on the high side, or always on the low side of 128, it figures something has affected the engine that will keep it operating at this point for a longer term. So, rather than correcting with a "short term correction" (integrator) and then throwing the value away, it better make a "long term correction" and save it. These long term corrections are call "Block Learns", one for the left side of the engine and one for the right.

The Block Learns look just like the Integrators. They theoretically can range from 1 to 255, with a mid-point, or neutral or "normal" value of 128. They are used just like the Integrators. They are multipliers in the fuel calculation equation. The main difference between a Block Learn and an Integrator is that the Block Learn is stored in the PCM, in volatile memory. And there is a Block Learn, or long term fuel correction factor, for each Cell in the BLM matrix. The Integrators are used once and thrown away (this is a little bit of a simplification, but it is essentially how it works).

When you pull the power to the PCM, you lose the volatile memory. The only thing in the volatile memory seems to be the Block Learns, the stored DTC's and the "learned idle" value for the IAC motor. So, when you "reset" your computer, you "reset" the Block Learns to the default value, which is 128. And when people say the PCM learns about changes to the engine, this it the primary learning area… the Block Learns. Pull the PCM power and clear the Block Learns. Start the car and let it idle, watching the LBL or RBL. It will start at 128. Switch to the corresponding Integrator, and it will NOT be 128. It will be mostly on one side of 128. Gradually, the PCM will move the BL in the same direction as the INT. This pushes the BL to one side of 128, and pulls the INT back down closer to 128, but still moving slightly above or below 128.

It appears that the BLM's can not go below 108. When they reach 108, the PCM will set a "rich" code. This doesn't necessarily mean the O2 sensor is faulty. It may just be that something is causing the PCM to add way more fuel than the motor needs, and the long term corrections can not subtract enough fuel to overcome that seemingly "rich" condition. Similarly, it appears that the maximum value for a BLM is 160, and when that value is reached, a "lean" code will be set.

Now remember, there are 16 fuel BLM "Cells". If you did what was described above, your "idle" Cell (16) will have rebuilt the BL for that Cell, but all of the other Cells will still be at 128, because you have not operated the car under the conditions that define those Cells. You need to drive it, and you need to make sure it operates over a broad range of RPM and engine load. This will assure you that you have reached a stable value for the BL's in each of the fuel map Cells. Now you can start trying to extract these values from the PCM. This is where a data collection type software beats the ScanMaster… it will record the data for you.

Try and get the LBL and RBL values for a range of Cells. This requires that you display the "CEL" and when you get the one you want, switch quickly to RBL or LBL and have someone write down what you see. This is easy for Cell 16 = idle, but harder for the high load cells. But, try to get idle (16), max rpm/max load (15) and one or two of the lower ones (02, or 03) and some mid ones (7, 8, 9 or 10).

If you have made a significant change to your engine, example an AFPR set at 38psi (no vacuum), rather than the factory 43.5psi, you will see the effects of the change in the BL's for ALL Cells. In this example, you might find that all the BL's have gone into the low or mid 130's to add the extra fuel that the lower pressure is not providing. If all the BL's are close to each other, and LBL and RBL are not too far apart in each Cell, try to think of what you did that would be requiring more or less fuel. You should be able to explain it away.

But, let's say you see differences:

If LBL for a Cell is a lot different than RBL for that Cell, there is something affecting one side of the engine. Example would be a leaky or clogged injector, an exhaust leak or a misfire. This is somewhat subjective, but I would suggest you look for reasons when the difference from right to left is 5 or greater.
If the low load/low RPM cells (16, 02, 03) are well above 128, but the high load/high RPM Cells are close to 128, you might have a small or medium vacuum leak.
And let's clarify a couple of misconceptions:

If your BL's are above 128, it is telling you that IF your PCM was not making these corrections, the engine would be running lean in closed loop operation. But, it is making the corrections, so the engine is neither lean, nor rich. It is using the corrections to stay exactly it 14.7:1.
If your BL's are below 128, it is telling you that IF your PCM was not making the corrections, the engine would be running rich in closed loop operation. But, it is making the corrections, so the engine is neither lean, nor rich. It is using the corrections to stay exactly it 14.7:1.
You engine can not run lean or rich in closed loop, unless the control system is not working, or the oxygen sensors are providing incorrect information. They will provide incorrect information if the are defective, there is an exhaust leak, there is a leaky injector, or there is a miss.

 

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Not to get too nit-picky, but that is not from the "ScanMaster instructions". ScanMaster included virtually NOTHING of value with the unit. What you quoted is the online guide the ScanMaster that I wrote, to try and overcome the poor job Ramchargers did with the ScanMaster.

When you quote from someone else's document, it is a simple matter of courtesy to correctly identify the source.

Why not give him the whole link and let him read it for himself.

http://members.aol.com/InjuneerZZ/ScanMast.htm

 

Sorry for the mis-quote Injuneer!

 

[QUOTE=OBE1 95Z28]
It appears that the BLM's can not go below 108. When they reach 108, the PCM will set a "rich" code. This doesn't necessarily mean the O2 sensor is faulty. It may just be that something is causing the PCM to add way more fuel than the motor needs, and the long term corrections can not subtract enough fuel to overcome that seemingly "rich" condition. Similarly, it appears that the maximum value for a BLM is 160, and when that value is reached, a "lean" code will be set.

Fred:

Correct me if I am wrong but a "miss" can also cause this condition will it not??? By the way...Really nice information, it's too bad that the manufacturer cannot include good solid information like this with its product. Well written and to the point

 

A misfire will cause the BLM's to increase, just like an exhaust leak before the O2 sensors. The O2 sensor "sees" the extra oxygen in the exhaust, caused by the unburned air/fuel in the misfiring cylinder, and the PCM tries to richen the mixture.

A leaky injector will cause the BLM's to drop. The excess fuel consumes some of the left-over air in the exhaust, and the O2 "sees" a rich condtion, and the PCM tries to lean it out.