89vette

I printed Trax's article P730 on basic speed density programming. Nice reading for the 4 1/2 hour trip to LA. I understand the VE tables now and what they mean and how to optimize them. On the MAF car, the airflow tables are 2 dimentional. How do you account for load? I never really thought about it before. I see no table that adds or subtracts fuel based on load except for the AE fuel tables. Since I pretty much have te AE fuel straightened out, I want to begin the fine tuning. Is load based on RPM vs airflow or is it based on airflow vs TPS? Is the point of MAF fine tuning to adjust the MAF tables so block learns are at or near 128? It seems impossible to get the integer to stay at 128. While cruising, my integer always races up to 145 or so in cell 15 while the block learn is 119 everytime I add a little bit of throttle. I seem to be long term rich and short term lean. At WOT, the MAF maxes out at 3950 RPM with the 396. Maybe speed density will be a winter project but for now I want to learn all I can about the $6E code.

Thanks,
Jason

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89 Vette 6 speed
CNC heads, crane cam, Miniram, headers
Soon to be 396 Small Block!

[This message has been edited by 89vette (edited April 26, 2001).]

GregWestphal

iTrader: (1)

Load is represented by LV8, ie: load variable. Since the MAF sensor measure airflow, it sort-of accounts for the load on the engine through the additional airflow going into the engine and matching up the amount fuel needed through a linear correlation (MAF tables). Of course, load is different than airflow, which is why the spark advance table is based on LV8 instead of airflow. AE is just a change in load, acting like a carb's pump shot when you step on the gas. Once you go into PE, then the PE tables take over and add the additional fuel necessary. Yes, the MAF tables are to be adjusted to keep the block learns at 128. Just match up the airflow value with each area that you're running lean/rich, and adjust the count (I think that's what it's called) to correct it. I know that maxing the MAF out isn't a real problem since the PE vs. RPM table is/can be used to compensate for that.

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Greg Westphal
'87 IROC 305TPI/A4

89vette

Thanks Greg. That's what I thought. Does anyone know how load is calculated? I know there is an LV8 scaling factor set to 1.25. I never touched that.

Jason

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89 Vette 6 speed
CNC heads, crane cam, Miniram, headers
Soon to be 396 Small Block!

Z-BOSS

I know that maxing the MAF out isn't a real problem since the PE vs. RPM table is/can be used to compensate for that.

I'm going to take it what you mean by PE vs RPM is the same thing as (WOT%Change to fuel/air ratio Vs RPM)please correct me if I'm wrong.
I don't see anything labled PE(power enrichemnet) in the tables on the ARAP bin.

GregWestphal

iTrader: (1)

The only notes I have indicate that LV8 is (MAF/RPM)*scaling factor, but that's a little off, like by a factor of 3800, give or take a couple hundred.

Z-BOSS: Yes, we're talking about the same table. I think TunerCat mislabels it WOT, but it's really Power Enrichment since you don't have to have it wide open (floored) to go into PE. You'll notice that in a couple tables comparing PE vs. %TPS.

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Greg Westphal
'87 IROC 305TPI/A4

89vette

OK. So what I want to do is ignore load, and ignore O2. Then I adjust the MAF tables so that my block learns are 128 through every airflow reading? Or do you lock the BLM at 128 and and use the integrator for tuning? What about the AE fuel? Won't that skew the integrator? Currently my block learns are all pretty much at 125/128. The problem is that my integrator flies all over the place when I give it more fuel. My head is spinning!

Grim Reaper

Locking the BLM to 128 makes it easier to tune IMO. The INT is 5 times more "finer" than the BLM and gives you a common reference point. The disadvantage of locking the BLM to 128 is that if your settings are way off, you could trigger an O2 SES code (too rich or too lean). Hurts nothing, just means you are way off.

One point, you should gently and gradually push down on the accelerator to get scan values. There is a transition as values (load on SD or gm/sec on MAF) change and rapid changes cause erroneous readings due to "transition". So give it gently and gradual increase of throttle and this will minimize "transition" problems.

afgun

How do you lock the BLM to 128?

89vette

Using GMEPro, I choose the direct edit/data dump option. Choose defult. Display as decimal. Go to section 04D0. Change column 4 and 5 to 128. That should do it.

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89 Six Speed FX3 coupe
More Performance 396cid specs:
Callies 4340 crank 3.875 stroke
Lunati Pro-Mod 5.85" rods
SRP Pistons 14cc dish
Comp Cams Custom cam 550 lift 220/229 duration
10.8:1 compression
AFR 195 competition ported heads
Miniram and TPIS 1 3/4" headers

Z-BOSS

Then which table would control WOT?
Is the MAF tables for open loop, do they effect the idle quality?

GregWestphal

iTrader: (1)

The PE tables, which Tunercat mistakenly calls WOT. The MAF tables are for all running conditions, except limp home mode. Yes, they do effect the idle quality, as well as spark advance.

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Greg Westphal
'87 IROC 305TPI/A4