I've done a good many cars and all of them were tuned in open loop and left that way. Never have had any complaints of bad gas mileage, bad power, broken motors...etc. As long as routine maintenance was done, the car remained running the same way.

after getting into a discussion with another board member here i'm wondering who else does this for cars that are fully tuned (no basemaps, no just WOT tuning and leaving the rest on a basemap)

https://honda-tech.com/forums/honda-prelude-4/do-you-have-run-o2-sensor-2835520/

IMO, you do not need O2 feedback when every other sensor has been compensated correctly. Now if you read that thread, please try to explain to me wtf he is talking about.

 

Its pretty common around here... Just takes a bit more time tuning part throttle/idle

 

Hey there Q16racer,

Basically there is outside forces that affect how a car burns fuel.

I would honestly pick up http://store.boxwrench.net/Engine-Ma...Book_p_75.html this book

I read it about 2 years ago and Loved it, it really sheds some light on how engine theory and tuning works that way when you ask questions like these that are hard to answer thoroughly to be honest.

But I'll try and fill you in on some things that I notice.

Outside air temp changes A/F ratio of the car, in the morning it might be 14.2:1 in the afternoon it might be 14.8:1 "Open loop mode"

The elevation changes will drastically change A/F ratio, I was in Utah 2 weeks ago and noticed since they are at 5000 feet elevation their octane level was 1 notch I believe lower then it was in Oregon. "for all 3 otane ratings"

In my particular setup I have a section that is closed loop and a section that is open loop and that switches over at a specific map value which would be slightly less vacuum then 275Millibar .. I believe don't quote me on that. so when I tap the throttle it goes outside of closed loop and ventures into open loop land.

You don't really gain anything from being in open loop 100% of the time "I have asked this question before and it went no where" it is however a very interesting concept to me.

What I have learned tuning is you get the car to idle with the right AF ratio with open loop on "which is also how you tune" then once you have your tune dialed in correctly and it idles properly, you then enable closed loop. In my specific setup NeptuneRTP "Fantastic tuning software" you have the ability to change the max sweep to allow your ecu to either add or subtract fuel based on the readings from the narrow band o2 signal your primary oxygen sensor is receiving, in open loop its pretty static when your car idles, when your in closed loop you will see the AF fluctuate around .75 AF higher/lower then stoich "14.7:1"

What are you trying to gain by not running an O2 sensor?

To answer your other question about compensation values

referencing Neptune they have an IAT compensation table for Ignition and fuel
how much fuel to add subtract at a givin temp "this is an interpolated scale" at 32 degrees add this much fuel/subtract this much fuel at 100 degrees IAT add this much fuel/subtract this much fuel.

same with ignition timing

There is also a Compensation correction for ECT "Engine Coolant Temp"

They have default compensation values and there isn't a whole lot of people that I personally know that really know "Engine Theory" to say with 100% what these values should be... Personally I don't change them.

Hopefully this will spawn off some more questions.

Hope this helps.


--Aaron

 

i know all that already, lol. Bought that book ~4 years ago. Been doing this for awhile.

when you tune in open loop, you can run leaner mixtures that running in closed loop will not allow unless you are using a wideband as your ecu o2 feedback.

 

That's what I like, Wideband O2 as closed loop input... Make the target AFRs what you want and it hits them. Not to mention that you can adjust the values for when the ECU crosses between the two. Honestly IMO keeping it in open loop is old school. Specially considering the software & hardware we have available to us these days.

 

how is it old school? 99% of cars i tune will not have their own wideband much less know much about what is happening to their car. They just want it to run right and make good power. Some cars do have widebands but dont want to pay me to wire it up.

im still interested to hear how running in open loop is old school

 

How long does it take you to wire a wide band O2?

If they want it to run properly and make power they would be better off spending the money on installing a wide band O2 vs paying $100+/hr on a dyno and run open loop.

 

how can you call it tuning without a wideband, seems to be more of guessing without it

 

I am assuming that he is talking about after the car has been tuned using a wideband O2. After that they put the customers stock narrow band back in or plug the O2 bung and run the ROM/ECU in open loop.

 

its the fact that it takes up time. I have flat rates for tuning and most people in this area think anything that isnt ebay prices is expensive. Not only that, but i dont get any breaks on what my boss charges per hour on the dyno so yes, wiring something to take up more time that really isnt necessary just loses me money. Another thing, its often that i dont know exactly what a car does and does not have when they bring the car to the shop. If they already had it wired up and ready then i wouldnt have a problem setting it up. Not running a stock o2 sensor is not going to blow up an engine or hurt its power. Once it has been tuned (part throttle and wide open throttle) it will stay tuned given the IAT and ECT compensations (and other associated functions) or correct for that particular car.

Some people have very different opinions on this topic and thats fine. I have done numerous setups and never had anyone calling me to complain. No news is good news eh? I'm glad we can have a true discussion here without all the crap talk getting in the way like the other guy.

 

I love closed loop with wideband support, but the truth is widebands go dead earlier than stock O2s... at least in most cases... and by most cases I mean budget widebands, which are still growing in popularity. This leaves closed loop either erroring out if everything is setup properly, or causing issues if not. In either case 99.9% of the population, if they're properly tuned, would have better results over time with closed loop disabled... Save the ones that travel into drastically different climates or elevations than they were originally tuned in... the previously stated .1%.

 

The way I learned to tune, which seems to make the best sense is

get the car running "that day" "that elevation" "that temperature" that "humidity level" all peachy and making great power, then enable closed loop.

Sure you *might have to fiddle with compensation values but perhaps not.. from what knowledge I have gained over the last 2 years doing this and talking to people about it the goal is the same thing, power and reliability.

I think in HRtunings response I have asked him about compensation values a year or 2 ago when I tuned my H22A but for the most part what compensation values are left there are generally pretty good "unless its been modified in the last 2 years"

By the way Digging the RD-1

--Aaron

 

The stock settings pretty well cover the spectrum. Of course certain setups may need some tweaking. There's no rule of time, if you modify the setup you may need to modify the compensations and the tune altogether, depending on what you modified. Of course closed loop will correct that for you in some cases, at lower loads anyway.

Thanks.

 

lol yea. Given how many wideband sensors and units i have been through i can believe that without missing a beat.

 

That .1% would just so happen to include where I live on the East coast of Canada. Where you can see all 4 seasons in one day. For instance, In the summer I can travel 100km and go from 30°C with a humidity in the 60s, to 20°C and dense pea soup fog then into 40°C and a humidity in the 90-100 range. Gotta love living near the Bay of Fundy.

 

No doubt, you're part of the .1%

 

Quick question, When I place a s300 in closed loop is there anywhere where i can view the actual numbers that r being used in a fuel table or can all i c is whats going on with the injectors right now like duty cycle and pulse width? I know I can c % of autotune base but thats just a estimate and not whats going on when in closed loop mode

I use my closed loop at first because I didnt have anyone to really drive me around while I tune. Iv been so unscientific lately and have had it in open loop, datalogging small drives, coming back to the house and adjusting it. haha It kinda ruins the whole tune on the fly deal that makes these ems's so great.

I agree that leaving it in open loop is completely fine. Most damage is gonna happen at wot where the stock o2 (will it still throw a cel if it reads stoich or leaner at wot? if so will placing it in open loop affect that feature? like on a chipped ecu or even hondata) isnt even utilized and most set the wideband to stop feeding back at a few pounds before atmospheric as far as closed loop. They may still run some sorta lean protection (i just found that it doesnt work when using full thorttle shifting, any input on that?) and of course a boost protection.

 

any inputs?/bump

 

Lol, that guy is an ***. In one part of that thread he said he was a honda master tech. Than he was PMing me later trying to be my butt buddie. I was ragging hard on him for being a honda tech than he said he never said he was that. He actually went back and edited out his posting.

He was an ***, and if anyone is the hack, it was that guy.

 

ok......bump for tech input

 

i left my car in open loop. running closed loop is possible but required lots of actual street tuning. driving around in a lot of different conditions and temperatures to get it to run correctly. the larger the fuel injector the harder and longer it will take to properly tune.

if your air/fuel is correct you don't really need to run in closed loop.