So after reading around about the ethanol in fuel now. Iv noticed some people changing there stoich to 14.1:1 instead of the stock 14.7:1 to add more fuel to the engine. Well I have searched and searched and can not find any info about the blm. Would I still tune to 128? I ask this because in closed loop I got everything around 14.1 on the wideband. I also changed the wideband from stock to 14.1 readout. Anyway I put the truck in open loop and took it for a short drive and it read out 16-17 afr, would that indicate the ve tables were off since I tuned to 128? So I started adding to the ve tables. After raising the whole ve table by 12 points the truck runs rite around 14.1 AFR in open loop across most driving conditions. Now in this process, did I do anything/assume wrong or is it better tuning the ve tables in open loop with WB? also since I changed stoich should i just continue to run in open loop? The computer I have is a 7747 and i use Winaldl to log and tunerpro to tune. I'm afraid that if i go back to CL that the BLM tables will be way off so iv been driving in OL. Thank you in advance. Oh and im just using one VE table merged so I dont confuse anyone with the amount of points I added.

 

I was reading more about stuff, would I need to change the 02 stuff to reach the 128 blm at 14.1 instead of looking for a different blm number?

 

No, the O2 sensor measures Lambda.

The stoich AFR calibration parameter isn't used in open loop, only in closed loop.

RBob.

 

So open loop runs strictly off the VE table? Why would I have to move the whole table up by 12 points to get it in the correct area? Is there something else effecting fueling? In closed loop it would run around 14 afr and when I switched to open it ran 16-17 afr.

 

Your opening post doesn't really make sense. You state that you tuned the VE tables to 128 BLM with the stoich at 14.7.

Then changed the stoich value to 14.1 and the reported engine AFR went leaner, to the 16 - 17's while in open loop. That can't be caused by commanding a richer AFR. Something else is going on.

RBob.

 

Sorry for the confusion. I changed the stoich AFR to 14.1 in the ecu code and the wideband. After that I began to log BLM data with winaldl and change the ve tables accordingly to get it to 14.1. After that I decided to mess with AE and decided to try running in open loop and the first thing I noticed was the 16-17 AFR on the wideband while driving at low speeds under 45 mph. I went home at tried bumping the VE table up by 5 points and it helped so I tried another 5 and then 2 after another test drive which brought me to a 14.1 afr in open loop. I have not tried closed loop yet but it did max the upper end of my VE table out and made it idle around 10-12 afr. At the very least it runs great now. Im just confused as to why the ve table was off that much between open loop and closed loop. I hope you understand what im trying to explain.

 

> The stoich AFR calibration parameter isn't used in open loop, only in closed loop.

Open loop uses a different commanded AFR value/table then closed loop. There is more to change then just the stoich value. These two tables are used for hte open loop commanded AFR:

COLD ENGINE AIR/FUEL vs VACUUM
COLD ENG TEMP AFR vs COOLANT

RBob.

 

After more reading I found that the AFR vs vacuum table is added to the AFR vs coolant. I went in and zeroed out the vacuum table and set my ve table back to where they were before and was able to get around 14.1 in open loop. Why would it be called COLD ENGINE AIR/FUEL vs VACUUM if its used even when the engine is warm?

 

You could have just left your wb settings the way it was, o2 sensor reads lambda and lambda 1 is always stoich, so the gauge would read 14.7 the the actual afr would be 14.1 in the exhaust.

Changing stoich in the bin does help the ecu do its math right in closed loop and yes 128 is still that target for blms.

To dial in ve table quickly lock in openloop, set target afr to stoich for openloop, use the nb and wb, the nb will swing fast back and forth at stoich, using both nb & wb gives you two pieces of data to compare, this way if one sensor is not reading correctly you will see it.

Remember everything needs to be decayed out befor you make changes to ve table and make sure your injector tables are setup correct.

I always say a car computer is just a calculator, if you take two wrong numbers and add them together you will get a wrong answer, another way put, garbage in = gargabe out.

 

Do you have a smog pump with air injection to headers/cat converter?
If so-mine always injects air to the headers when in open loop.

 

I haven't had a air pump in years since NY city in now safety only but that would make sence, when cold the car is in open loop to warm up, cat also need to warm up to work correctly, should be able to change setting to divert the air to atmosphere.

 

Thank you for your replies, im less confused now about the BLM and afr stuff. The truck is an s10 with an l31 crate motor and 700r4. No emissions at all. I got to reading about the 7427 computer and decided to swap to that because its faster and can control my efans. So hopefully it will run better all around since the motor is all stock. I never could get the 7747 to idle properly in drive, probably had something to do with idle settings, but i could never get it how i wanted. It will be for sale soon if anyone wants it. it has a 28 pin socket installed on the board. But thank you again for the help. Im sure ill be back for more questions in the future.