Has anyone here made successful MAF table adjustments for a ported MAF using Tunercat? My 95Z has a ported MAF and was wanting to adjust the tables for it but don't know exactly where to start and was wondering if it was even worth it or not. Can always go back to my non-ported MAF if not. Thanks.

Ken R. 95Z

 

Ahh yes, the totally worthless PITA causestuningproblemsfromhell ported MAF, I used 10% increase, so take all your MAF tables (all 4 seperate sets) and multiply by 1.1 for a 10% increase. This brought my open loop tables right into accuracy at low throttle, and did my WOT adjustments just fine also without touching the MAF tables again.

So I'd say its close to a 10% difference since that seems to have been what worked for me.

 

Dr. would you suggest this same thing for a car with no internal mods but also has the ported maf? My mods are listed below.

Hooker LTs
No cat
LT4KM
TB bypass
Moroso CAI
UD pulley
3" FlowMaster Cat-back
No EGR
No AIR pump
Ported MAF

I also have a DataMaster file of two of my dyno runs. Would you take a look at them and see what there is to see?

Thanks

 

I dont really like Datamaster, but I could reinstall it and take a look.

Any car with the ported maf could probably benefit, it SHOULD throw your BLMs off since it wont read accurately after that. I got VERY lucky in finding someone selling UNTOUCHED MAF ends, with no MAF unit itself, so I only payed about $25, after that I never touched the damn thing again. It causes more harm than good, its a good example of free mods going too far. It gains nothing and causes problems.

Looking at your BLMs is going to tell you how your AF is going right now, and the MAF may not read linearly across the scale either. Since I'm not a fluid dynamics person, I can only make guesses, that without a straight shot at the intake it may flow a certain way at low RPM and a certain way at high RPM, and I'm not really guessing that they are quite the same, but who knows. Maybe even idle is enough velocity to overcome chopping it up how we did, hmm.

I also wonder of the two, which is the greater sin, I'm thinking that removing the plenum may not be as bad as removing the screen, but I think there is a slight variance in how the screen attaches from year to year (in terms of putting it back)? Dont know for sure about that one.

 

I have reinstalled my screen. It just pops back in and is secured with a large ring. Not a big deal to reinstall at all. I think I will try the table adjustment and see how it goes, probably with and w/o the screen. I will have some wideband dyno runs to compare and post the results.

Thanks for the help.

If you do get datamaster installed and would take a look at the runs, let me know.

Thanks again.

 

You should be able to export the file from DataMaster as a ".cvs" file. Then anyone with Excel or 1-2-3 can view it and manipulate it.

Just curious.... has anyone compared the stock MAF calibration table for a non-WS6 car to one from a WS6? It would be interesting to see if the factory tuning attempts to account for the difference in inlet/outlet ducting, and how it affects flow calibration at various air flow levels.

 

The question has been asked before on the Edit list, but I dont really remember the outcome. My guess might be though that they are the same, hmm..?

I just wonder how linear the change is when gutting the MAF, mostly as far as accurate metering, and also which is more important the screen or the divider, as far as metering or etc

 

I'm a bit confused here on this topic, I'm hoping someone can help me out...

Ok... so people are gutting their MAF's, which allows more air to flow through the intake system. And they want to know how to readjust their MAF tables in the PCM to account for the extra airflow.

Take this example... if someone were to port their MAF and not readjust the tables, and they drive the car for a few days. The engine would be getting more air than the computer thinks, and the car would run lean. Wouldn't the O2 sensors see this lean condition, and the computer learn to add more fuel for that specific table cell? Isn't this the whole point of the computer being able to "learn"?

The only advantage I can see to adjusting the tables is to keep the BLM's exactly at 128, but what's the big deal if they go up a little as the computer adds more fuel? Would they shoot all the way up to 160 or whatever the limit is? I'm thinking that after the computer learns what to do in closed loop, WOT would be adjusted too... because doesn't it use the BLM's from the last cell you were in before you enter PE?

Thanks for any help you guys can give... much appreciated

 

It is desireable for closed loop people to be at 128 or slightly below (apperantly), it would not send you to 160 though, not that drastic.

But again, I still question how accurate the metering is, and is it still linear or will it read poorly at low RPM and ok at high RPM (intake velocity)? I just dont know.

 

i recalibrated my MAF and its still stock. my BLMs were in the 11x range most of the time so i just scaled all the values down a little to bring them up to 128ish. this also helps WOT b/c the computer defaults to 128 in cell 15 and all my values are right under 128 so im not running near as rich as i had before. it is possible GM actually scales all tables this way so people run kinda rich at WOT to further help eliminate the chances of detonation. just a theory but you never know.

 

When you say GM designed our cars to run rich at WOT, what kind of ratios are you talking about? What would a stock LT1 a/f ratio be at WOT when checked on a wideband dyno? Cause what I'm learning in school is that you want it to be rich at WOT for most power... you want every oxygen molecule entering the cylinder to have a HC molecule... and in order to get this you richen it up and have a few extra HC's... the ratio should be around 12:1, which is richer than the 14.7:1 desired at idle. I'm asking this question because I've read of people leaning out their mixtures at WOT... why are they doing so? Are they richer than 12:1 and want to lean it out so it gets back to 12:1???

 

i wasnt that techical. i used no wideband O2 sensor to determine what my actual A/F was. i adjusted the tables with information available from the computers fuel managment or BLMs. also to clarify..i never said GM runs cars rich. i just said it is possible they do so guys wont accidently blow up motors running them too lean.

 

I was told that LT1's make best power around 12.2-12.3:1. But every car is a little different. Some like to be a little fatter, some a little leaner.
I think I remember hearing stock was between 11.5:1 and 12:1, but I can't remember.


Someone explain to me what the difference is between chaning the MAF tables and injector constant in order to bring the blm's where you want them. Seems like most people just raise the injector constant a little to try and lean the car out.
Is one better than the other? Should I start learning how to mess with the MAF tables rather than slightly raising the injector constant?

 

I've seen Fred post 11.7:1 seeming to be common, I went for 13.0:1

 

I've been wondering the same thing. I got rid of my ported setup and went back to the original.
The problem is that I don't have the screen.

I have a stock WS6 MAF Calibration Table.
I'll have to change the format because its in Notepad but anyone that want to look at can shot me an e-mail.