MAF Table help
03-20-2007, 07:48 AM
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MAF Table help
ok, Guys, need a little help understanding the MAF Table fueling. I kinda new to tuning, and have read the Sticky's, but it's just not sinking in.
Got an 85 vette, stock l98, with the intake ported open...at Idle, I'm so lean it's scary. Running headers and a heated o2...here is what I've got:
Idle RPM: 800
gpm/sec: 7.91
base PW: 1.42
BLM 160 and steady at 160
INT is steady at 128
Closed loop
I'm running the $6E ARAP code.
Inj const:24...these are the stock 85 vette injectors
From what I've read (and correct me if I'm wrong), I need to adjust the MAF Tables, but I'm having a real hard time understanding the correlation between the Tables, and the fueling. With the above readings, I'm assuming I need to adjust the Table 1 entries. But I'm having a hard time figuring out how much, and which way. If I raise the values, will that richen me up, or take me leaner? I'm just trying to get off the 160 BLM's...I can adjust the inj const, which I have, but it doesn't seem to really affect the BLM'S...I took it all the way to 21 for a constant, and my BLM's only dropped to 158, which seems to tell me that I'm scary lean at the 24 constant. Looking for just a little guidance to get me on my way...
Cheers,
Michael
Got an 85 vette, stock l98, with the intake ported open...at Idle, I'm so lean it's scary. Running headers and a heated o2...here is what I've got:
Idle RPM: 800
gpm/sec: 7.91
base PW: 1.42
BLM 160 and steady at 160
INT is steady at 128
Closed loop
I'm running the $6E ARAP code.
Inj const:24...these are the stock 85 vette injectors
From what I've read (and correct me if I'm wrong), I need to adjust the MAF Tables, but I'm having a real hard time understanding the correlation between the Tables, and the fueling. With the above readings, I'm assuming I need to adjust the Table 1 entries. But I'm having a hard time figuring out how much, and which way. If I raise the values, will that richen me up, or take me leaner? I'm just trying to get off the 160 BLM's...I can adjust the inj const, which I have, but it doesn't seem to really affect the BLM'S...I took it all the way to 21 for a constant, and my BLM's only dropped to 158, which seems to tell me that I'm scary lean at the 24 constant. Looking for just a little guidance to get me on my way...
Cheers,
Michael
03-20-2007, 03:05 PM
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Car: 1989 GTA
Engine: 5.7 TPI
Transmission: A4
Axle/Gears: 3.23
Re: MAF Table help
Do you have an aftermarket cam? Are your BLMs lean at all g/sec? Raising the values in MAF 1 is supposed to richen but if that and lowering FI constants don't make the numbers prettier then you might have to look at the mechanical aspects of the engine.
03-20-2007, 07:56 PM
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Re: MAF Table help
stock cam...blms only high at idle in cell 1 when driving in cell 6...all the others look to be in the 128-132 range....
03-20-2007, 10:23 PM
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Car: 92 Form, 91 Z28, 89 GTA, 86 Z28
Engine: 5.7 TPI, LG4
Transmission: 700R4, 700R4
Axle/Gears: 3.27, 2.73
Re: MAF Table help
i kind of thought all L98's had 22 lb/hr injectors, even in vettes. Never heard otherwise at least.
Here's a quick (and shortcutted way) to think about the MAF.
The REAL airflow is X. The MAF makes Y volts from X REAL airflow.
This voltage goes to the ECU.
The ECU says this Y voltage = Z ECU airflow using the MAF Tables and scalars.
ECU injects Z/14.7 Fuel
Z ECU airflow is too lean in your case, because Z is too low.
Moral: Raise ECU airflow to raise ECU fuel.
Here's a quick (and shortcutted way) to think about the MAF.
The REAL airflow is X. The MAF makes Y volts from X REAL airflow.
This voltage goes to the ECU.
The ECU says this Y voltage = Z ECU airflow using the MAF Tables and scalars.
ECU injects Z/14.7 Fuel
Z ECU airflow is too lean in your case, because Z is too low.
Moral: Raise ECU airflow to raise ECU fuel.
03-21-2007, 06:25 AM
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Re: MAF Table help
i kind of thought all L98's had 22 lb/hr injectors, even in vettes. Never heard otherwise at least.
Here's a quick (and shortcutted way) to think about the MAF.
The REAL airflow is X. The MAF makes Y volts from X REAL airflow.
This voltage goes to the ECU.
The ECU says this Y voltage = Z ECU airflow using the MAF Tables and scalars.
ECU injects Z/14.7 Fuel
Z ECU airflow is too lean in your case, because Z is too low.
Moral: Raise ECU airflow to raise ECU fuel.
Here's a quick (and shortcutted way) to think about the MAF.
The REAL airflow is X. The MAF makes Y volts from X REAL airflow.
This voltage goes to the ECU.
The ECU says this Y voltage = Z ECU airflow using the MAF Tables and scalars.
ECU injects Z/14.7 Fuel
Z ECU airflow is too lean in your case, because Z is too low.
Moral: Raise ECU airflow to raise ECU fuel.
Cheers,
Michael
03-21-2007, 09:44 PM
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Car: 92 Form, 91 Z28, 89 GTA, 86 Z28
Engine: 5.7 TPI, LG4
Transmission: 700R4, 700R4
Axle/Gears: 3.27, 2.73
Re: MAF Table help
Again, I don't know the details, but if they are "RATED" 24# at 43.5psi, they would flow 21.5# at 35psi. I don't know what yours are rated at though.
Just something to consider.
Just something to consider.
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