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MAF Table Grams/Sec Limits

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Old Jun 11, 2009 | 08:19 PM
  #1  
Duts87ss's Avatar
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From: Ocean Springs, MS
Car: 1987 Monte Carlo SS
Engine: HSR 383 AFR180/268XFI EBL
Transmission: 200-4R, Edge 2800 L/U
Axle/Gears: 7.5/3.73/PowerTrax No-Slip
MAF Table Grams/Sec Limits

Is each MAF table supposed to have its own limit? My table #2 will not accept a number larger than 47.81.

I recently changed injectors because I thought I might be pushing my old ones to their limit later on, but they must have been flowing much more than what I had the constant set. After installing the new injectors and only changing the injector constant, the car was way lean. I adjusted all the MAF tables last night based on a datalog from yesterday afternoon. The car drove very poorly today; when I checked the .bin, the top few fields in tables 2-5 were all the same value (I bet this hurts driveability, don't you think )

I guess I'm going to have to start from scratch again.
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Old Jun 11, 2009 | 09:06 PM
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From: Chasing Electrons
Car: check
Engine: check
Transmission: check
Re: MAF Table Grams/Sec Limits

Originally Posted by Duts87ss
Is each MAF table supposed to have its own limit? My table #2 will not accept a number larger than 47.81.
Yes, check out the MAF Miscellanea and MAF Scalar Tables threads in Chap5 , '165 section of the tuning guidebook.

RBob.
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Old Jun 12, 2009 | 08:57 AM
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From: Chasing Electrons
Car: check
Engine: check
Transmission: check
Re: MAF Table Grams/Sec Limits

After changing nothing but the injectors the MAF tables should be left alone.

Play with the injector constant until the BLMs are centered the best that they can be. Do this at the higher PW areas. So with some decent load get the BLMs around 128.

Then play with the injector compensation tables to tweak in any areas that are rich or lean. This will have the most affect in lower load areas. Because of the shorter PW's an injector compensation change has more affect on the AFR.

Then and only at the very end should the MAF tables be changed. Changing the injectors doesn't change the calibration of the MAF. It changes other items, such as the injector flow constant and the injector compensation requirements.

Dependent upon how much of a change in injector flow was made you may also need to change the AE and proportional gains.

Changing the MAF tables is a tweak that should only be used as a last resort.

RBob.
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