What does "open loop" mean
 

What does it mean for a car to go open loop? I have alse heard it said that the car won't even go open loop from the factory. What does open loop mean in terms of engine and tranny operation????

Hi.

Closed loop: A/F's determined by feedback from the front O2's.

Open loop: A/F's determined by programmed fuel tables in the PCM.

"Closed loop" is derived from control systems terminology & refers to any system that actively & continuously self-corrects to a known state via a feedback loop - in this case it's Stioic ( 14.x:1) & the feedback is provided by the O2 voltages.

The inability to go Open loop prevents a vehicle from producing it's rated power.

Hit Google for more ...

Cheers
Bubba

You must be one of those people who like to hear their own voice....

Open and Closed Loop are two 'modes' that an engine operates in. Open Loop is activated at WOT and feeds more fuel to the engine to create more power. Instead of a 13-14 A/F you end up with an A/F of around 12.1

Try searching, if not just this site, Google has more information than you could ever use, and probably answer your questions quicker than waiting on someone here. If you search/research yourself you'll have a better understanding of your answer.

...You talkin' to me, buckwheat ??? :D

As I recall, your truck took 'feeding more fuel' to a whole new level !

BTW - did you get your tuning straightened out?

Cheers
Bubba

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2006 F150/FX4CR (Camo Ranch)

Haha MGDfan that comment wasn't directed at you :lol:

I've got a new Tune from Mike, but haven't installed it yet as I've been busy with work and now I'm out of town this week. I was hoping to head up to Troyer's DynoDay but if its the weekend of Nov 10-11, I'll be gone then too. Might just hafta suck it up and head back to my local dyno and make a few pulls with the new tune....

NCSU, If that comment wasn't directed at MDFan, then it had to be directed at me. If it was, then you are just a rude person. If you did not want to answer my question, you did not have to reply. Do you think yourself some sort of self proclaimed arbitar of who can post what on this site. I did not read anywhere in the user agreement that all questions were supposed to be submitted for your approval before being posted. You must be a very small person who is very insecure in your self worth, who feels the need to be derogatory to others in order to feel better about your own meaningless, pathetic, and insignificant life. Did it make you feel like a 'big man' to make your rude comment. Hopefully you impressed yourself. I know you sure impressed me. It must feel nice to feel so superior to others.

:lurk:

.........

Lions and Tigers and Bears Oh My! :help:

here Lakeport this might help

Closed Loop fuel control operation is when the PCM is using the feedback from the oxygen sensors to constantly adjust the air fuel ratio to a 14.64:1 A/F ratio.

Open Loop fuel control operation is when the engine makes its real power. In this mode, the PCM ignores the feedback from the oxygen sensors and no longer forces the engine to run a 14.64:1 A/F ratio, instead, it uses the signal coming in from the MAF meter or MAS to determine how much fuel and timing to put into the engine, based on hand-coded values in lookup tables that are based primarily on load, and the result is richer A/F ratios and that allows the engine to tolerate more spark advance

you go open loop at approximately 80% throttle

:lurk: word

Hi.

Okay. NCSU, please feel free to redirect that comment back to me. I don't mind. It's kinda true anyway :lol:

So Navi, ya troll, move along. Go wax your truck or fix it - there must be something needs doing :) . You can leave the popcorn.

Cheers :beers:
Bubba

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2006 F150/FX4CR (Camo Ranch)

Whatdaya expect bubba? With all the crap I bolted on to it, there is always something that could use a tweak.

Besides, I have two A4LD trannies in the garage that need to turn into one good one. Lots of work to do, I'll have to troll through here later:angel:

yahda yahda yahda This love fest must end before winter to be a true summer romance!!!!!!!!!!!:lol:

Hey Lakeport,

Let me give you a bit of perspective on this, OK?

First - Keep in mind that there are a lot of people here who have been here a LONG time - so they have seen the same basic questions asked literally thousands of times - this is precisely why most of them will tell "newbies" who are asking all of the obvious "newbie" questions (like you have been doing here for some time now, in your desire for more information) to use the SEARCH feature - this is simply because virtually everything you and everyone else who is relatively new to this site have asked here, has already been covered here many, MANY times - and thus is readily available by simply using the SEARCH feature. That's why it's here, so that anyone can look up anything they want to know 24 hrs a day.

Could it have been put a bit more politely? Yeah, maybe - but then I have to confess that I find myself doing the same thing from time to time, so I really am in no position to "throw darts" at anyone over that. :)

Anyway, he's just trying to remind you to get into the habit of using the SEARCH feature, as that way, you get your answers much quicker, in far more detail with the hundreds of thousands of posts here, and others don't have to take the time to type out the same answers that have been posted so many times before - that's all, so please don't take offense, my friend. :)

Just trying to lend a little perspective, and I hope that helps a bit, OK?

Briefly - the answers you have been given in this thread are basically correct - in C/L, the engine is always running at stoich A/F (typically 14.64:1 on pump gas) as the PCM is constantly taking data from the front O2 sensors and adjusting the A/F ratio based on that data. But running at stoich A/F also means the engine cannot tolerate a lot of spark - it runs at stoich A/F as that is the ideal A/F ratio when a lot of power is not needed, to burn all the fuel, best emissions, etc. Then O/L operation is transitioned to at various throttle positions, but typically at heavier throttle - when you need power - and this happens at anywhere from about 60% to 90% throttle or so, depending on the vehicle and it's tuning - that is where the A/F ratio is now determined by the combination of the lookup tables and the MAF sensors transfer function, and is supposed to get significantly richer, and more spark gets added to the motor so it can make more power.

Have fun,