blue86iroc

iTrader: (2)

After much confusion, I'm finally beginning to understand this PROM tuning business... however, I've got a question regarding the MAF tables.

In a previous post, I read that in order to tune your BLM, you would find the airflow reading at that rich/lean BLM cell and input it into the MAF table (at least, that's the way that I understood it). Now, from looking at the MAF tables in WinBin, all I see are voltages that correspond to grams/sec. How would I know which to adjust; i.e. there is no BLM cell indicator. Would I have to make any changes to the "Maximum Air Flow vs. RPM" table?

I have searched through the archives and didn't really find anything that explained how to make adjustments to these tables in relation to the BLM readings (well, one post did have a link to another thread, but it was for the old messageboard system so it didn't work). If I locked the BLMs at 128 (is this even possible on a MAF car?), would I just use the INT reading to adjust?

I've got my laptop and cable ready but I haven't actually started to gather any data yet. I want to ensure that I have a basic understanding before I get involved with it. Thanks, all.

Grim Reaper

This is the ONE AREA where MAF falls short of SD IMO.

The MAF's measuring of airflow simulates load (and the MAT for that matter) and there are a number of factors why you may be at 128/128 at one particular air flow (say low speed high load) and off for the same airflow but say at a different engine speed/load factor. Air temp, elevation and humidity also affect the MAF.

Once you REALLY get into "tweaking" those MAF Scalar Tables, you really appreciate the way SD works and the fact that you modify a specific Load/RPM in the SD's VE tables and it ONLY affects that Load/RPM.

Did you know that I have found AT LEAST 5 different MAF Scalar Tables calibration on JUST the different 1989 BINs? The BEST MAF Scalar Table that seems to get people the closest to 128/128 is the ARAP.

I have a LOT more I can explain, but you REALLY better understand how the MAF tables really work by reviewing the hack first. There are areas of the table that ARE NOT DEFINED in any Bin Editor that I have seen that you need to pay attention to. Also, you need to watch out for the "upper threshold". Often if you want to increase those, you are often at the "limit" and the only way to increase the upper boundary is to alter the Injector Constant and the RESCALE ALL THE MAF TABLES.

If you haven't been burning eproms for at least one year and haven't study the hack for at least 6 months...forget it. This is WAY beyond people just learning and you can really screw yourself up.

blue86iroc

iTrader: (2)

So, therefore, if I get my MAF tables adjusted perfectly (let's say), and then I take the car to a different elevation (for example), those "perfect adjustments" will be thrown off?

I have been reading up on MAF and SD, but there's a lot more that I have to read... I was considering switching to SD but I heard that MAF is more tolerable to slight modifications of the engine. However, if I am going to get into custom setups I might as well entertain the idea of switching to SD. I don't want to get off topic with discussing MAF or SD; I just wanted to mention my thoughts about it (I've seen the debates that arise... )

Grumpy

You really want to avoid editng the MAF stuff as much as possible.
There should be some searchable stuff here, about MAFs, I've tired to explain it several times. Using injector constant and battery voltage corrections are MUCH BETTER option, and then the PE AFR stuff for WOT AFR.

MikeT 88IROC350

The MAF tables are not that impossible. Glenn, try not to steer the new guys away from MAF systems. Everyone has their own opinion. I think blue86 just wanted some basics. He admits he has far to go. As Grumpy suggests, start with other areas in your MAF bin first. Then when you think you have things close, go slow on the MAF tables. Just work on one at a time, and take lots of data. You need several scans under different conditions, to determine where to make a change.

I just changed 2 entries around 7gm/sec, to help richen the idle. My BLM was solid at 137, but this was the first scan after I completed lots of porting work on the base manifold. I concluded that more air=leaner mixture.

Just my 2cents!

blue86iroc

iTrader: (2)

Thanks for the responses. I've decided that I'm going to stick with my MAF because I really don't want to swap ECMs and do some cable repinning. Even so, I think that as long as I go slow and take my time as you guys suggested I shouldn't have many problems.

Matt87GTA

That is the route that I have been going.... Unfortunately, due to my geographical location, I haven't messed with my PROM since early November..... I should have the GTA out on the road again in the next few weeks though, and I will be back at the PROM tuning duties once again.

Grim Reaper

I am not trying to steer "new guys" from MAF - just giving a GOOD DOSAGE of warning...because it's needed. Guys with less than a year shouldn't be playing with the MAF scalar tables too much, or they may get bit in the butt when they least expect it.

Second, MAF by its very nature will never be 100% accurate just because of humitidy, elevation and ambient air temp. Remember, the MAT sensor on a MAF cars does nothing for the Air Fuel calibration. SD is much easier to tune for fuel calibration changes than MAF, especially if you are striving for perfection.

If you are getting BLM readings between 120-136 with MAF, leave it alone and live with it. If you want to get closer to 128/128, then go SD because you'll never get MAF there in ALL conditions.

kvu

some reading for you maf boys