Since the car is no longer a daily driver, I'm considering switching to an open loop tune. Do we have writeups on how to accomplish this?

I currently still use a MAF, but the VE is close.

Is this what I need to change to remain in OL permanently?

- OLFA vs. ECT vs. MAP (14.628/value=commanded AFR)
- Closed Loop Enable vs. IAT (some unreachable number)

Anyone have a polished HPT .bin I could review with OL tuning?

 

- set the closed loop enable temperature to something really high (Engine->Fuel Control->Open and Closed Loop)
- set the OpenLoop F/A table to your desired values
- set the PE table to your desired values
- disable the MAF by setting MAF Fail Frequency to 0 (Engine->General)

Now you should be in open loop

 

1. Easy enough
2. How do I determine which cells I want good fuel economy vs. good performance
3. I've already got the PE values where I want them from my MAF tune - unless something needs to change here.
4. Easy enough.

 

I have done several open loop tunes and you don't need to set the MAF fail to 0. There is a difference between Open Loop and Speed Density.

 

Chad - I just replied to your e-mail. Do you have a version in HPT format?

 

Yup. I'll send it over here in a few for ya.

 

Thank you, Sir!

 

Its sent. Its a 395ci open loop/Speed Density Tune.

 

I know there's a difference, but if you don't disable the MAF sensor than you have to deal with accuracy of the MAF table and calibrate it to match the VE table. Correct?

 

This is correct, but he asked what does it take to put the car into open loop. That isn't a requirement for open loop, only for Speed Density/MAFLess. Your theory is dead correct though, but not a "requirement".

 

You are absolutely correct, not a requirement. Thanks!

 

I've been running open loop, through the MAF, for about 2 years. I set the Closed loop enable temp to a high *C value. F/A table is stock at operating temps.

My VE calculated from NoGo's VE equation. MAF table is Bumped at the lower Hz to richen at idle. AFRs are pretty close to the F/A Open Loop table. Does have an irritating 3000 RPM/Low kPa instantaneous drop in the AFR (from about 14.3 to 12.5) which I guess is due to a change in filtering (calibration).

I'll try MAFLESS soon - as soon as the new TPS/VE OS is available from EFILive.

I wish they had an EFI University 3 years ago - and the LS1 PCM knowledge we have now!!!
EFILive sure makes things so much easier!!

FWIW.

 

Joel - Unless you plan on keeping the open loop afr table set at stock, your ve will be off. I found this out the hard way. I had my ve table dialed in to where it needed to be, then changed the Open loop afr table to command 14.63 and guess what, my afr was all off. It is important that you tune the ve table with the open loop table that you will keep in the car, otherwise, your chasing your own tail. FYI

 

My NoGo VE was calculated without wideband or narrowband input. It was verified via the wideband.
I guess the values will be off via a MAFLESS/BEN tune somewhat - I'll set the F/A table to a single value (12.9?) for that.
I just want to play a little with SD......both Open and Closed Loop.

Eventually I want to go back to-> Closed Loop through the MAF.

 

Chad,
Great info and I remember reading about this. Did you figure out why this happens? I would think that once the VE table was correct that it shouldn't matter what AFR you command. I'm missing something?????

 

I found this out when I had my VE table dialed in at 12.96(1.13). I switched it to 14.63(1.00) because I am in open loop all the time and wanted my gas miileage back. When I did this, the cells ranged from 13.3-14.0, where before all were in the 12.7-13.1 area. I think it has to do with the airflow and calculation of the VE. You are changing the amount, where in turn this will affect the AFR.

 

Click this link here Aaron.

https://ls1tech.com/forums/showthrea...&highlight=AFR

 

Thanks Chad!

 

Can you explain the difference or tell me where I can find the differences between these two modes? TIA.

I have been researching, but I am still confused as to "what" the actual differences are. What does the PCM do differently in SD vs Open Loop?

Just looking for knowledge. I thought SD was the PCM making decisions for fueling based primarily on MAP and RPM i.e. the VE table. I realaize there are other factors utilized (e.g. IAT, ECT, etc). There are no O2's needed in SD? A wideband would be useful, but narrowbands have no value. However, there is no "switch" or PID to indicate SD. Correct? Other key ingedient is that no MAF is needed? How is commanded AFR derived in SD? Is some algorithm converting VE values into a multiplier to affect 14.7:1?

As I understand it, "Open Loop" is used by the PCM during startup and WOT. In both of these instances, the PCM ignores O2 outputs. Do fuel trims still exist during Open Loop, and do they have any effect on fueling? Do they exist in SD and/or have effect? I can change parameters in the PCM to force Open Loop all the time. If I do this, (as I understand it) Commanded AFR would be dictated by the Open Loop AFR table. What if I change WOT/PE settings to essentially have the car in PE mode at anything above idle? Is Commnaded AFR then primarily (or solely) driven by PE vs RPM table? Do fuel trims exist and/or have any impact in Open Loop/PE mode?

Sorry for all the questions, I just haven't ever seen where this has been laid out nicely. Instead, I seem to find conflicting information from all the sites I keep reading. Maybe I just need to step away from the internet.

 

Just as you said, you are correct.

SD is when you run the car without a MAF, only relying on the MAP and VE for your fueling.

Open loop is when you don't use oxygen sensors at all.(wideband) You take away the learning process when you tune so it is much faster.

You can run Open loop all the time if your car is dialed in for a certain AFR.