Is there any reason not to set the car to stay in open loop mode all the time? One of my O2 sensors is reading way off. I think it got damaged, and was thinking about tuning the car to stay in open loop mode all the time. Is this a bad or good idea? I was also thinking doing a speed density tune and elimating the MAF at the same time would be a good idea. This is a 600rwhp N/A motor.

 

if you get rid of the maf and the rear O2, and run in open loop all the time you will run on a "pre programed" stoic ratio and loose a lot of fuel control!!

 

What do you mean, how so?

 

the maf tells the PCM how much air is entering the engine, if it even gets dirty it will give you issues. Removing it will force you to run in "limp in mode" or controled open loop!

 

speed density is great as long as you can get everything dialed in. plus you dont have to worry about maxing out the maf.

 

not to be a wise guy, but - if you want to run in open loop all the time then trade in all your fi for a carburetor

with one exception ( msd's mefi-iv unit ) i have never had good driveability with open loop / speed density type systems

just my opinion.................

 

Nothing wrong with OLSD. I run it pretty much in most conditions in my tune. Use a custom OS with a VE/IAT factor, dial in the VE at one temperature then check the VE at different temps and apply the AFR BEN to the VE/IAT table. I don't believe HPT has this feature so that will make it very difficult to get OLSD fuel calculations as accurate as you can in EFI LIVE, still its doable and far superior to MAF fueling when done correctly.

 

It makes sense to do it to me. I can dial in my tune for the air density/temperature of the day right before I race. I don't have to worry about the car reacting after the fact. The O2 sensor is only used at part throttle operations. Its main purpose is to give me best fuel economy during cruising. My car is going to be raced 90% of the time. So using the O2 seems pointless.

As for speed density mode, the MAF is just restricting the air flow. Its not going to be as accurate of a gauge of air flow during racing conditions.

I guess my real quick is has anyone had success in doing both? Is it worth the trouble of having to check my tunes during races?

 

Oh and are you joking with the carb remark? Do you even know how a pcm works? Last time I checked a carb can't give me perfect amount of fuel and timing for each individual rpm spot?

 

I've been running OLSD for about 3 years now. The bird has stock like manners thru school zones, get's 22 mpg on the hiway and puts down a little shy of 500/500 on the rear wheels. EFILive's custom OS 5 (for the 99+ 512 pcms) is a big contributing factor for this.

 

In OLSD you actually GAIN complete control of your commanded fueling, you dont loose anything.

Ive been running OLSD for as long as i remember, it takes a bit of tuning to get it right but once it is set, i much prefer it to closed loop maf.

 

How do I completely disable closed loop mode?

 

You guys are all making me want to switch to EFI. I just bought HPT too

 

OLSD is not really a good first step for you if you are new to tuning, it takes a good tuning knowledge base to get. If you cant tune then dont jump right into it.

 

Set the Closed Loop Enable ECT vs. IAT to its maximum value.

 

I just started doing the olsd tuning the other day.. Its kinda confusing/annoying at first, but eventually it makes sense... W/ my cam the car idles at 80-85kpa...

 

Alpha N!

 

 

alpha-n, isnt that in efi's cos5?? VE based on throttle %...

 

yessir.