brahm

I've searched, and searched and searched, and can't seem to find any good tutorials on how to calibrate my maf I'm looking at this sticky

https://www.camaroz28.com/forums/sho...d.php?t=505190


It seems to be a key part, and one of the first steps of getting a WOT tune.. any info would be great. I have tunercat, datamaster and freescan.

Thanks
-Brahm

sbs

http://tinyurl.com/lj7b7a

bobdec

The post you referenced in your OP was a '96 OBD2, I assume your '94 is running and OBD1 PCM , no AFR readings , just BLM's to go with. Below is a cut/paste from " http://www.lt1pcmtuning.com/tips/ " (one of the hits above) A prerequisite is everything is perfect mechanically with your engine, no vacuum leaks, etc and all your other sensors are OK. This s/b fine tuning, not used to mask any other problems.

MAF Sensor Tables
There are four tables for the MAF, which split up its total frequency->airflow grid.
First, find the airflow reading for your idle in your logs. Then, find the closest value(s) in the MAF sensor tables; you will sometimes have to alter two cells to affect one airflow range.
To richen your fuel mixture (BLMs > 128), increase the value(s) you found as mentioned above.
To lean the fuel mixture (BLMs < 128), simply decrease the appropriate MAF cells as mentioned above.
These values are also efficiently modified using percentages (%), or multiplying the values (1.xx to richen, 0.xx to lean). Start with 1% (1.01/0.99) changes for every 2 BLMs off; so, a BLM of 118 would require a 5% decrease (128 - 118 = 10 / 2 = 5), or multiplying the MAF airflow value(s) by 0.95. Again, trial and error will be needed to see if you have overshot a BLM of 128 with your changes.

brahm

gee thanks steve.. I never thought of that.. oh wait lets look at the results it returned..

LT1 PCM Tuning - OBDI/OBDII PCM Tuning/Programming Service

hmmm.. A guy I can pay to do it.. hmm.. Not helping me learn to tune my maf there..

LT1howto.com :: LT1 PCM Tuning for Dummies
Some basic **** I already read, that doesn't really go to deep into it.

LT1 MAF? 94' Z28 MAF SENSOR DIFFERENT THAN 97' T/A MAF SENSOR ...
Hmm, that sure doesn't help me tune it..

PCM tuning & Computer Diagnostics on www.ls1lt1.com | boardreader
hmm.. no tuning tutorials there.

Tuning the OBDI LT1 Engine
Oh sweet I can send him my PCM for 50$..great that helped me learn how to tune my maf..

Some differences in MAF mode vs SD Mode - Cadillac Owners Group
hmm.. the difference between Speed Density and A maf.. oh that's just what I was looking for.


Procharged LT1 Second Tune ????? - LS1TECH
oh wait.. another pst talking about sending your pcm out to be tuned..


...shall I go on? Next time try to be a little helpful and not a troll, I asked a very specific question that Im' looking for a very specific answer. I'm pretty sure i'm capable of using google. Hence the words in my original post.

"I've searched, and searched and searched, and can't seem to find any good tutorials on how to calibrate my maf I'm looking at this sticky"

Searched and Searched, and Searched would imlpy hmm maybe I did try google.
any GOOD tutorials is the subject of which I am attempting to locate, of which you did not provide.

Thanks, yours truly.. not fond of *******s who have nothing better to do then troll forums.
-Brahm

brahm

Hi Bobdec,
Thanks for your response. I did read that, but I wasn't 100% sure on a couple things.. Basically what that is saying is the way to adjust your maf is by watching your BLMs and shooting for 128, aren't there other things that effect your BLMs besides the MAF (ie spark)? Do I only alter it at idle, or do I then make a curve based on the % I change it at idle up threw the whole range. I understand there are some programs out there you can use to create a MAF calibration curve is this correct?

bobdec

Brahm, Sorry Long Post ... Yes the BLM's are an indication of what the O2 sensors are reading AFTER the PCM calculates the injector PW. The PCM looks at Air flow (AFGS), RPM, temperature, MAP, BARO pressure, injector size, among other things. Then calculates a pulse width for the injectors to add fuel. The timing, plugs, wires, vacuum, etc also play a part in how the fuel is efficiently burnt. They all come together and then the O2's feedback (in closed loop) the end results to the PCM and if AFR is not 14.7 the PCM starts to correct the mixture. When it corrects it updates the BLM's to remember the setting for each BLM CELL. What you have to do is look at a log then manually find the BLM Cells that you are significantly (+/- 7%) off. Then find the AF gms/sec readings for those cells and go to the MAF tables to alter the AF readings that are in error. Trick is to keep transition in the MAF tables smooth without any big jumps or going up then down in AF gms/sec between entries. That's what some of the s/w spread sheets do for you.
By adjusting the MAF tables you are tweaking the air flow reading to the PCM. EG: If BLM cell XX at 2.6 gms/sec on you log has a BLM of 135. Look at MAF table 1 ... When the MAS sends a 1488HZ signal to the PCM it converts that to 2.45 gms/sec of air and adds appropriate fuel based on the all the sensor info above. If you alter the table to say 1488 HZ is 2.55 gms/sec (+4%) of air then the PCM will add 4% more fuel and the BLM should decrease 4% (135 to 129). You only need to adjust the BLM cells that are way out not the complete table. If you are out at all ranges then it's more likely an injector constant or other sensor feeding bad info to the PCM. In some radically cammed cars the O2 readings are erroneous and you would need to take a different approach. In that case a wideband would verify the OS are correct or reading wrong, I don't think that is the case hear.

95Blackhawk

Yeah, that is my original post. I have an excel spreadsheet I use to calibrate the MAF and have been using it for years. If someone is willing to put it out on the web for all to use, I will give it to them. There is no tutorial on the web to do it. I have looked and no one has conveyed their knowledge so I learned myself.

The sorry thing is it takes time and patience to get it right and it can be complex for a beginner. It is not as easy as some have stated. the MAF generally will be off differently at different locations. The MAF's I have calibrated have either started off rich then went lean in the upper Hz range or vice versa. So obviously there is a crossover point. It's not just run once and add 5% across the board because your BLM's are off by 10. It is a systematic approach that takes time. I would estimated at least 6-10 recalibrations to get your BLM's in the 126-130 range across the board. Where the MAF sees WOT AFGS flows, it is easier because the MAF gets less precise the higher the Hz.

Shoot me a PM with your email and I will get the spreadsheet to you. I also owe someone else the spreadsheet now that I am home from vacation.

Ben

LearJet

can you post that spreadsheet here?

95Blackhawk

You tell me how and I will do so.

formula934

Use mediafire.com and upload to there. Then it will give you a link and just paste in this thread. Its really easy only takes a minute.

SamIndy

Facts:
- ACDelco MAF sensor (93-00) uses a heated wire at 200C. When this temperature lowers with incoming air, the PCM sends more hz to bring it back to 200C.
- MAF calibration tables allow variable in grams/second. Constant is the hz.
- 94 Corvette has lower numbers in these calibration tables than a 94 Camaro.
- Example: @ 2896hz
the Corvette is calibrated at 10.19 gms/sec
The Camaro is calibrated at 10.46 gms/sec

Hypothesis:
- Obviously the Corvette has a better air cleaner than the bottleneck Camaro cleaner. Therefore colder air.
- MAF calibration is more complicated than the opinions expressed in the preceding replies. The role of MAT (Mass Air Temperature) is under-estimated.
- Therefore calibrations in the MAT tables are necessary to reach a stoic closed loop.

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