What do all these numbers mean? (Open Loop Table)

I'm trying to learn more about the Open Loop table. I did a post a few days ago but it doesn't seem to many people either know or don't care about my other post. Anyways.........

I am going to assume the following:

On a cold start, your car is using the open loop fuel table and switches to closed loop once the pre determaned coolant temp switches it to closed loop. During open loop, you are using the MAF, MAP, IAT, & ECT sensors, correct? ???

What I want to know is before I start "adjusting/tuning" my open loop table is, is it just a fuel multipler for the injectors? By increasing the numbers, do you increase the A/F ratio (make it richer) and vise versa?

Bill


http://www.cofba.org/users/billiumss...op%20Table.jpg

if your volumetric eff table is set up correctly, the table in closed loop is 14.7, the computer assumes the ve table has been corrected via ltrims values that are stored and takes that number, "which is supposed to be 14.7" and divides that by the number you see in that table, its just like the power enrichment table durring cell 22. 14.7/1.13 = 13 air fuel ratio. Thats why the ltrim system is in place. it has accurate measurement from the o2s at 14.7 so it knows it can set up all the tables to be right with that main table for data. So it can pull or add fuel where needed to make everything right.

I'm not talking closed loop though.

The table above is the one that "sets" the A/F in open loop right?

The O2s aren't up to temp yet on a cold start so Ltrim value don't mean anything for the first few minutes of running because the PCM doesn't "Know" what to do yet until full closed loop by using the O2s.


So, what is the main difference between running Open Loop all the time and SD? Do they both use the VE table? SD doesn't use the MAF, Open Loop does.

I don't want to be confused on "Open Loop" I do know what SD is/does, basically what a FAST PCM is.

i understand that. The computer stores the ltrims in a grid based on the values you set for the ltrim boundrys.

It uses that information even when the car is just started and durring open loop modes, that is why it is accurrate. so, when you start your car and see the car is requesting 13. af and the wideband is showing 13 , that means that the car has a good ve table and it has learned what it needs to be.

Quote:

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Originally Posted by Billiumss

The table above is the one that "sets" the A/F in open loop right?


So, what is the main difference between running Open Loop all the time and SD? Do they both use the VE table? SD doesn't use the MAF, Open Loop does.

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yup

there isnt any that i know of, yes, I dont believe open loop uses the maf...it uses the ve as the verification that your tune is dead on and then uses the table you posted as the multiplyer meaning when your coolant temp is at a specific point in conjunction with what your map sensor is reading it will pull that cell multiplyer to tell the engine what a/f ratio it should run at...if your ve is accurate whatever that cell commands should be dead on...if it isnt then it wont be accurate...either way you can tune around the ve it just means that table isnt going to be a perfect multiplyer...in a perfect world your ve would be dead on and you could dial in the table very easily.

Quote:

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Originally Posted by foff667

I dont believe open loop uses the maf...it uses the ve as the verification that your tune is dead on and then uses the table you posted as the multiplyer meaning when your coolant temp is at a specific point.............

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Nope.
Open Loop means without integrated (into the loop) Narrowband O2 sensors.
If you are SD and LTFTs aren't actively adjusting, via O2s, then you are Open Loop.
I run Open Loop, full time, through the MAF - no O2 sensor integration.