Flat out,

A car will drive better when its BLM's cross 128 EVENLY. This means they will not sit at 128 the entire time but when you run an anaylisis on the datalog you will average close to 128. or if you want to get simple and look at datamasters Histogram and see all white.

IF the car is consistantly on the lean side or consistantly on the RICH side the car will adjust but not adjust enough to have the best driveablity you can have. And this isn't just a picky thing.. its a good deal.

I have had cars that sit consistantly in the 140's.. and buck..

I've had cars sit at 110 and guys complain of a stink.

The idea of the BLM"s automatically adjusting thows out the reason behind tuning for driveablity in the first place.. Quite simply it just doens't work so nicely.

For those who have consistanly off BLM's. (All reds or all greens in the histogram) I urge you to fix the problem by adding in those areas of the MAF table or on a speed density car modify that area of VE. and watch how much better it is to drive.

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Let me ask a seperate question. If you guys rely on BLM's to pull the car into a reasonablly driveable condition.. DO you also put crazy timing in the car and ride the knock senosr? after all isn't the computer adjusting and fixing the problme in the tune?


The above to cases are wrong. You should never be riding a O2 sensor or knock sensor.

Anthor case of useing fuel trims to fix bad tuning is the DFI guys. Ask them how well the cars drive when your riding on a correction factor. and hell those use widebands

 

Isn't that your opinion though? Not really fact. Where is the fact?
I offered my opinion and you shot it down as being wrong.

Isn't the purpose of a block learn multiplier to correct those minor mistakes in fueling?

As long as it is adjusting I don't see what's wrong. Of course if you want to talk about extreme conditions where the blms are real low or real high then I understand making corrections to the ve tables or maf tables. I do it.

And your second example is completely different, and you know that.
In the same sense we could pull out a whole bunch of pe fueling and hope that the blms will increase and add some extra fuel back into the motor.

 

OK cool. That is a good answer. Yea, it may be right that our cars just can't adjust when they are too far away from "perfect" 128. I too had my car running in the 110's on my BLM's and could smell gas. So, the reality is the BLM's won't tell the whole story.

I personally would suggest that people look at their cell boundaries. On my car, the factory setting essentially allowed for only 8 cells to be utilzed. What a joke...0-1200, 1200-1500, 1500-2000, 2000+ RPM! **somebody correct me if I am wrong on this for the stock 95** Hell, below 1200, you are either idling (cell 16) or DFCO (cell 17). Take a look and you will see what I mean. I expanded mine so that all cells were used, obviously not equally, but at least used. I went 1500, 1500-2200, 2200-2800, 2800+

This does tie with the original questions because with expanded cells, you can then manipulate them and "drill down" to the areas you are having problems and thus change you MAF in those areas easier. When you drill down, the range of the AFGS in that cell become more obvious. This is of course if you are looking to change your MAF tables at all (I know some aren't).

Ben

 

Correct..

Its also important to note that different setups should require different Cell bounderies simply by the way they work. Different camshafts change high/low load areas and cell bounderies should be change to correspond to that.

I went threw alot of that nonsence with my eaton setup because boost was brought on so hard. It was quite a tuning nightmare.


One other important thign to note is not all cars will like the 14.7 or 128 deal. Some of the more extreme setups will take you for a bucking bronco ride at the slightest hint above 14.7.

One real cool thing about about the new tunercat definitions for the DA3 stuff is that you can change the O2 cross over reference. That way you can set a BLM's to work off say .650v instead of closer to .450

 

I have not updated my def file in like...forever.

So with changing over the crossover point, we can essentially run our cars at different AFR's in closed loop, non PE mode, is that what you are saying? Say if I want to have crossover at .35 v this might be 14.9 AFR for cruising?

If this is the case, it would be something I have been dreaming of for a LONG time.

Expound a bit if you would.

Ben

 

I believe what Alvin is referring to is only available in the DA3 files Ben.
Maybe TC can find a way to incorporate it into the EE file.
And yes, how you described it is how it should work.

 

Dan K- I know I'm not a professional tuner, and only have my car to go on as a reference point, but the same applies for me with the BLM issue. The car has improved DRAMATICALLY in all areas since I have recalibrated my MAF sensor for my current setup. Initially my blm's were hanging out very high, in the low 150's usually. After an 18% increase across the mAF curves, it then hung just low, in 118's or low 120's. Then I used an excel spreadsheet and some equations to dial in my MAF sensor. I didn't use as much data as I would have liked, but it seems to have done a grand job. My blms stay within about 3 of 128 at all times, and the car's mileage has gone up as well as smoothness and part throttle power.

I haven't experimented with the different blm cell boundaries, but that sounds like a very good point. Most of my data came from a relatively few number of blm cells. I was also wondering if my "jerkiness" at low speeds could be due to many quick changes between two blm cells that had slightly different values.

As for AFR ratios, I keep hearing about 12.6-13.4 or so being the best, but where? Does a linear AFR make the best power? Or is it better if it's fatter on the bottom and leaner on the top? I'm always reminded that in a dyno chart, its the area under the curve, not the peak power, that makes the car faster... so even if my AFR knocks a couple of peak hp down, if I gain an avg hp of 5 then I'm sitting pretty....


Jonota