Tuning Lt1 Maf Tables

Hey everyone. Just got my dads lt1 swapped 87 trans am rebuilt and running again. Its got a 230/236 duration and .544/.555 lift cam with ported heads and a mail order tune from PCM for less. Im using tunerpro and $ee hack for tuning. Ive only ever messed with VE tables and I dont quite get how your supposed to make changes to the maf tables because the table in tunerpro is in hertz and the $ee hack gives values in afgs/sec. Ive done a little research on how to edit the tables but its not making sense to me. If somebody could help me understand this better that would be awesome! I dont want to be stuck only being able to tune map based cars.

ignore the hz,

you need to find the airflow range that you want to tune, and increase or decrease the value in the table.

lets say your logs show you require 20% less fuel at ~25AFGS

find the value nearest to 25afgs in the table and multiply them by 0.80

then you have to smooth the surrounding cells. it helps to view the MAF table as a graph and ensure proper curvature. maf tables should maintain a decent curve without many spikes or dips. this actually allows you to tune the missing data fairly naturally by just re-drawing the curve based on your observed corrections.

if you ever view your graph and find that it doesn't look like the stock graph anymore (except kinda tilted or moved around a bit), you probably used bad data or something is wrong with your engine

If you are using the scanner in TunerproRT you can build a histogram table that will log the HZ vs fuel trim. I custom build a data output that averages both long term fuel trim values.

I do the same thing with HP Tuners for the Vortecs and LS engines. I have an Excel spread sheet I can copy the old MAF table into, the fuel trim values and it sputs out a new MAF table. Works very well.

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Originally Posted by Fast355

If you are using the scanner in TunerproRT you can build a histogram table that will log the HZ vs fuel trim. I custom build a data output that averages both long term fuel trim values.

I do the same thing with HP Tuners for the Vortecs and LS engines. I have an Excel spread sheet I can copy the old MAF table into, the fuel trim values and it sputs out a new MAF table. Works very well.

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This is what I do with mine as described above. If I saw a fuel trims that looked like this in average values, I would leave the table alone!

http://i243.photobucket.com/albums/f...psx0geqtdr.jpg

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Originally Posted by steveo

ignore the hz,

you need to find the airflow range that you want to tune, and increase or decrease the value in the table.

lets say your logs show you require 20% less fuel at ~25AFGS

find the value nearest to 25afgs in the table and multiply them by 0.80

then you have to smooth the surrounding cells. it helps to view the MAF table as a graph and ensure proper curvature. maf tables should maintain a decent curve without many spikes or dips. this actually allows you to tune the missing data fairly naturally by just re-drawing the curve based on your observed corrections.

if you ever view your graph and find that it doesn't look like the stock graph anymore (except kinda tilted or moved around a bit), you probably used bad data or something is wrong with your engine

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So in short ignore the hertz(left) side of the table and find the value closest to the value I want to edit in the afgs(right) side of the table. Sound right?

Quote:

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Originally Posted by Fast355

If you are using the scanner in TunerproRT you can build a histogram table that will log the HZ vs fuel trim. I custom build a data output that averages both long term fuel trim values.

I do the same thing with HP Tuners for the Vortecs and LS engines. I have an Excel spread sheet I can copy the old MAF table into, the fuel trim values and it sputs out a new MAF table. Works very well.

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Sounds cool but sounds well beyond my abilitys right now.

Quote:

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Originally Posted by Fast355

This is what I do with mine as described above. If I saw a fuel trims that looked like this in average values, I would leave the table alone!

http://i243.photobucket.com/albums/f...psx0geqtdr.jpg

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So I shouldnt even worry about editing any of the values in the picture I attached correct?Attachment 11003

Quote:

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Originally Posted by Dukes164

So in short ignore the hertz(left) side of the table and find the value closest to the value I want to edit in the afgs(right) side of the table. Sound right?


Sounds cool but sounds well beyond my abilitys right now.


So I shouldnt even worry about editing any of the values in the picture I attached correct?Attachment 11003

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Those values look pretty good to me. I like to keep it slightly richer than Zero. If you have a positive fuel trim in any area and go to power enrichment the fuel trims will lock positive and the PCM will add fuel across the whole RPM range while in PE. Stay a bit on the rich side and the fuel trim values will stay at Zero at WOT. In my experience staying slightly rich and letting the long terms pull a little fuel makes for a smoother running engine all around.

Quote:

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Originally Posted by Dukes164

So in short ignore the hertz(left) side of the table and find the value closest to the value I want to edit in the afgs(right) side of the table. Sound right?

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yes

Quote:

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If you are using the scanner in TunerproRT you can build a histogram table that will log the HZ vs fuel trim. I custom build a data output that averages both long term fuel trim values.

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in EE, the datastream only outputs calculated AFGS value (post maf table) instead of hz. could certainly use tunerpro to run maf afgs vs trim in a histogram

eehack, which he's using, will generate a history table on trims vs maf too (maybe even better, especially for a new tuner.. it can use INT data in a sane way, only picks records that make sense to use, etc, so you can just chuck logs at it and press 'analyze')

So I tried making some changes my tables based on what my wideband was telling and the car ran like crap. it would buck like crazy from 1500-2000 rpm and was almost undriveable. Also EE hack doesnt seem to like to read values from my wideband. Im using an lc-2, everything is setup correctly I've checked multiple times. Its hooked up on pin D27 EE has recognized its hooked up once otherwise it just stays around 7.35:1 and doesnt record any wideband data. Any idea why that is Steveo?

Quote:

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Originally Posted by Dukes164

So I tried making some changes my tables based on what my wideband was telling and the car ran like crap. it would buck like crazy from 1500-2000 rpm and was almost undriveable. Also EE hack doesnt seem to like to read values from my wideband. Im using an lc-2, everything is setup correctly I've checked multiple times. Its hooked up on pin D27 EE has recognized its hooked up once otherwise it just stays around 7.35:1 and doesnt record any wideband data. Any idea why that is Steveo?

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can you screenshot your settings so i can have a look?

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So I tried making some changes my tables based on what my wideband was telling and the car ran like crap

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probably misconfigured or not properly calibrated wideband. do you still have narrowband sensors? try tuning using your trims instead

With that cam try speed density mode. Engine pumps air back and forth at low rpm and maf goes crazy.
First use SD mode and dial VE at low and mid rpm and use wideband for wot later.

i betcha it'll work fine with a maf too.

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Originally Posted by steveo

i betcha it'll work fine with a maf too.

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^^^^^

I have tune some good sized, tight LSA cams and they all run better with a MAF.