Understanding Open loop / Closed loop Basics

In this video I give you a basic description of "open loop" VS "closed loop"
This may seem very basic however the question has been asked numerous times, whats the deference between the two, so I thought this would be a great example
With this knowledge I came to the conclusion without looking at the vehicle, how the engines low coolant temp was directly related to poor fuel mileage

[@speedchopwtf]

11 years later and this was super helpful. thank you!

[@robinsonsauto]

Great to hear!

[@hamzacar5027]

One of the best comprehensive definitions of open/close loop Thankyou Sir

[@upptowne]

I just purchased a scanner and this type of basics is exactly what want to learn. Thanks a lot

[@wedreamtogether]

I really appreciate you taking the time to make this video. In videos by "real fixes real fast" Duane often mentions open and closed loop, now I have a better understanding of what that is. Thank you!

[@nicholasvonrhine6311]

How cool the engine is constantly adjusting to be most efficient.

[@liam9613]

great that you go into so much detail in youtube video.... NO 1 mechanic on you tube

[@SuperCarfix]

I think both of you supper techs(Paul and Will)are inspiring the whole techs community. Thank you

[@ScannerDanner]

a comment on the video itself. i agree with the assessment a stuck open thermostat will cause extended open loop operation as well as a richer fuel.curve from lower coolant temp. the fluctuating O2 in open loop was weird but doesn't change the call or the theory behind the poor fuel.mileage.

[@baxrok2.]

Great job and a very thorough explanation.

[@tragichero7746]

Very helpful! So awesome how much you can learn by watching repair videos

[@medicaltechnicalathlete1359]

wow I learned all that easier than my college class haha and the best part is I didn't get bored! nice work!

[@robinsonsauto]

Two good knowledgeable assumptions, thank you for the feedback

[@Clockcash]

Great video. Thanks for the education. It was helpful.

[@robinsonsauto]

Thank you for the compliment, greatly appreciated

[@901gtsi]

Great video, cant wait till part 2.

[@robertcorriveau5889]

GREAT INFO !!!! THANK YOU its really well explain

[@AGuysGarage]

Great video. Thank you for the info. My ride is running cool right now too. "thinking the thermostat is probably toast" lower hose on the radiator is cool and upper hose is hot. but that explains my crap mpg for sure lol. i figured it was something like that. plannin on doin it when it gets a lil warmer.

[@SchneiderClassics]

nice, my prof shared this video with us, great explanation on open vs closed loop.

[@mattwolice9741]

Great explanation! Thanks!

[@arazaliguliyev]

Educational video, 👍 good job

[@robinsonsauto]

Thank you, its one of my favorable body styles as well

[@DavidKirba]

Thank you, this was very useful and informative :)

[@RZGOBLIN]

I can't wait, please Will put part 2 now!

[@robinsonsauto]

thanks for passing through

[@reweydewy]

Great work as usual! I really dig the older style Chevy/GMC trucks. Thanks for taking the time for this vid. Lets see part 2!

[@anandrattu]

Thanks it is very important information

[@spelunkerd]

Thanks for responding. On my 1998 Ram the O2 sensor page seems unsupported, even though I have the full enhanced package. I think it may be an issue with the truck. I don't see the typical O2 sensor pattern, more of a truncated one, which makes me think that it's an issue with the refresh rate sending data down the OBDII ports. I put a generic scope on one sensor, backprobed off the wires, and the typical sinusoidal swings are present there. I'll try it on some other vehicles.

[@websterchinyenze9914]

Thanks bro. Now it makes sense.

[@joshuaboyell779]

Love how the philly accent gets stronger and stronger as the video goes. Sounds like home.

[@robinsonsauto]

while in generic the only way i am aware of is on the "o2 sensor" monitor page i think its the 6th tab on the top when you select an o2 and start monitoring above the graph you will see the fuel system status, open or closed now while in enhance mode you can do the same however you also have the option to select it as one of the monitors on any of the meter, graphs and grids (this may not be an option on all makes and models) hope this helps

[@signatureimpressions6850]

Thank you sir! 👍🏽

[@robinsonsauto]

Thats a knowledgeable guess, thank you for the feed

[@ScannerDanner]

no problem, I think we are all good now. thanks

[@vincebauer4777]

great video I have my 98 town and country going in and out if closed loop seems like when I take my foot off pedal it goes into open loop tps.. seems to work ok o2.. seem to work great

[@thromboid]

Helpful explanation, thanks! Bad thermostat, maybe?

[@robinsonsauto]

Part 2 is up, great job

[@robinsonsauto]

I would look a little deeper first, even though most time it is the o2s, i would still do some basic testing to the circuit, if you would like stop by the forum @ toolsandtime. com and post the question, i can try to guide you in more detail if you would like.

[@robinsonsauto]

thank you sir, will be posting soon

[@robinsonsauto]

Thanks, stay tuned

[@robinsonsauto]

Thank you sir

[@twitchc2588]

good stuff

[@donnasturino8297]

Hi Robinsonauto thank you for this video it hit the nail on the head for me Pacific. Information it's. Very clear. And professional please have a Merry Christmas and a happy new year

[@robinsonsauto]

Yes that was autoenginuity, with the baseline model i don't believe you have any bidirectional controls, however they have enhancements you can purchases as a bundle or by make, the expansions give you bidirectional controls, all in all it seems pretty powerful, im still testing the limits and function to be honest

[@robinsonsauto]

Thank you

[@robinsonsauto]

Autoenginuity-pro line with enhancements, complete bundle cost around $1,200 however you can purchase basic and build from there, sure its not the best scan tool but works well for the most part, and fit the budget at the time lol i have others as well, was hoping to demonstrate this one for the people on a budget that cant afford a $10,000 full blown snap on

[@atamotua64]

urgent, please help... i have 2013 hyundai genesis coupe with only 15k miles... has exhaust and intake and runs perfect... NO chk engine light on... not sure if it's related to the mods, but my CAT, O2S, and HRT monitors fail the ready test for emissions... when i connect an obd2 scanner, FUELSYS1 says CL... but FUELSYS2 says "--?"... again, not sure if this is related to the above... but what would be the quickest way to pass emissions test?

[@SuperCarfix]

Thank you .Hey Will what are you using for scanner.

[@robinsonsauto]

Yup you got it

[@spelunkerd]

Will, is there a quick way with Autoenginuity to determine whether the vehicle is presently in open or closed loop?

[@MrEbanks]

Is the problem on the vehicle the thermostat?..... Thank you just wanna let you know this video helped me pass my ASE A8 test

[@wafi3187]

My one is showing fuel-sys 1 ol-fault and it’s only when I hit the gas pedal,and when car is running,I replaced my maf but it’s not fixed,so I am thinking its o2 sensor,what you think ?

[@spelunkerd]

I've been looking at autoenginuity and when I can scrounge the cash I think I'll go for it. Are you able to turn some devices on and off, for example cooling fans, etc? What are the weaknesses of that system? Were those screen shots you showed from autoenginuity?

[@dezblyan5125]

finally someone can explain to me open and closed loop in lamemens terms lol thanks

[@FarazAhmed-cb3cd]

you're truly lame!!

[@dezblyan5125]

Get a life not everyone is as smart as you😄

[@FarazAhmed-cb3cd]

hehehe

[@csn6234]

Blyan,s video corner "layman" dummy

[@mr_sowong9464]

@@csn6234 you missed the joke

[@hombresdevalor9024]

Hey! What diagnostic software you using in this video?! Thanks for the info on this subject that was getting me crazy on a p1129 i got on a 08 charger 2.7

[@Amopower]

Once in closed loop, the feedback from the O2 sensors gets used by the ECU, and then we should see the ups and downs...add fuel/take away...repeat. When in open loop, the O2 signal is not used, so we should see something steady. The text that says "open loop" in that software might be coming from the software itself and not the ECU.

[@thomasdrift7159]

L

[@abimariavargas7086]

Can u explain open loop fault . And open loop drive at idle what are the causes

[@RohanSanjith]

Don't know i think some problem with O2 sensor or maf

[@ScannerDanner]

I agree the O2 graph and loop statis do not jive. that O2 signal is showing closed loop fuel control even though the scan data showed open loop. i disagree on the 450mv constant you mention. this is only with a cold sensor i think this is a simple thing here. theory of systems do not always match reality. this system was clearly trimming the mixture regardless of that loop statis reading.

[@mikaeltulloch-reid7065]

Good!

[@VariagUral]

So it's normal that excessive idling causes 'open loop due to system failure' for non-heated O2S. Does it mean for heated sensor that I need to change it even if heated sensor monitor is ready?

[@wdwh4708]

Your explanation was fun and useful, but I have a question ????? Does the heat sensor have a primary role or does not matter

[@robinsonsauto]

Thank you, i really don't know to be honest, i would think any decent scanner should

[@SteveRobReviews]

Good stuff !! Do most generic scan tools actually say open and closed loop on the screen ?

[@angelc7984]

Hope you can help me , I’m driving my GMC Yukon on a drive cycle to complete the IM monitors for the evap blinking light it’s the last one I need to complete before I can go get my sticker. Well at the end of the drive cycle driving on the freeway on my way home, I have scan tool hooked up the whole time, I looked at the closed loop for a second and it said CL declined then it went back to CL. It was real quick I’m pretty sure that’s what it said, I couldn’t read it to well because I was driving. What does theat mean?

[@gradyhernandez5231]

it has an electronic feedback carb that I understand works in conjunction with the O-2 Sensor--so if it isnt reaching closed loop then that explains the increased gas consumption? am i correct? 1989 Dodge Ram 50 (import) 2.6 iter--5 speed. It should hav great gas mileage!!!!! Has o be 14.7:1 a/f ratio....

[@babysparrow1]

I have a code that says ( closed loop-B2). Is it running OK then? I have replaced the oxygen sensor 1 bank 2 but the code won't go away please help!

[@beastlychase]

Hello I am getting a p1129 on my Jeep Liberty closed loop will not achieve and I'm dumping a lot of gas into it where part two or what did you do to fix your problem

[@gradyhernandez5231]

ihave a 1989 dodge ram 50, and it seems to not be reaching closed loop condition,ses alot of gas for a 2.6 4 cylinder.. thermostat and/or temperature sending unit? repalce both of them..????

[@elieyounan9049]

So how does it mean when my check engine codes for "Faulty Heated Oxygen Sensor 1 Bank 1 Heated Oxygen Sensor 1 Bank 1 circuit is open or shorted Heated Oxygen Sensor 1 Bank 1 circuit electrical connection"

[@estrelladelnorte1308]

ok thanks!

[@ShamelessTR]

Curious if I can ask a question... I have a 98 Tahoe and I get a 02S heater core fault. Will replacing these 02S take care of my problem or should I look elsewhere first?

[@danielandujar5479]

I have a question. My Honda pilot 2003. 3.5 I hook up the scanner and with just the Switch on it shows a close loop Without starting the unit. Is this normal? And if not possible cause. Please thank's

[@RajuYadav-fd9wl]

what is the idol temprature for closed loop?

[@robinsonsauto]

Thank you for the feedback, sorry for dragging you into to this, to be honest i couldn't think of a more knowledgeable guy to ask, i will be the first to admit im far from perfect and your league of knowledge i make bad assumptions, i can see where the confusion came into play, showing that data was a bad decision on my part, and caused further confusion, i guess in the end we can learn from this

[@MrTwitch37]

Do you happen to know the preset coolant temperature requirement for 92-96 jeep cherokees?

[@-shortsfeed]

Are you from Delco or south jersey Mercer county area?

[@wafi3187]

My car shows OL-drive when I hit the gas ! Some people says it’s normal some people says it has a problem! Can some body tell me which one is right?

[@estrelladelnorte1308]

if you see above the two signals the fuel system status is reporting "open loop" are you saying that ECM "releases" the o2 to start reading otherwise they should read a flat steady signal? I think o2 start reading sooner but ECM ignores them till engine reaches desired temp, then it will go into closed loop. i am confused too now...

[@083rt]

Did he make a Part 2?

[@estrelladelnorte1308]

i got a question will!! if i have a bad o2 , will the engine go into closed loop?

[@stephaniebaby19]

Is there a second video? I have a dodge caravan 2000 and the reading say "insufficient coolant temperature for closed loop fuel control" not quite sure what that means and how to fix it. Now what you were explaining does sound like my car too. I will have it running for an hour and there is no heat and the fuel mileage is bad. How do i fix this? Please help! 😓🤔

[@RamchandPhagoo]

Sounds like the coolant temperature sensor might be faulty.

[@michaelpeterson4348]

1994 Dodge B-250 , 5.2 , this is a van I have completely gone through engine rebuild blue printed all new sensors OEM parts . All the sensors are working new ECM. Here is the issue. With the engine completely cold, turn the key to the on position the IAC opens way up (Setting itself up for a fast cold idle ) soon as you start the van the AIC closes to a slow idle position, and stays that way when the vehicle is fully warm, then runs great I just don’t have a cold fast idle. I believe something is happening during the cranking cycle what would cause this ? ( Engine was hooked up to a scan tool all sensors working New positive and negative battery cables all ground points cleaned off new 880 cold cranking amp Northstar battery , this is my personal vehicle it is my back up handicap van I’ve had it since brand new so it’s worth making everything work perfect , no wires have ever been cut ,11.35 cranking volts at the battery. I do have a plug in the EGR valve as I don’t like exhaust in my intake. DTCs are : 12 , 37 , 32 , 32 ( The blinking check engine light gave me a code 32 twice ) ( Engine almost acts like from key on position to actually starting engine going straight to “ Close loop mode “ ).

[@jameswalt6514]

Ok, great....so if coolant temp is 205 and scanner shows the 02 sensors are all good and hot and I'm still stuck in open loop due "defect".....what the heck could it be?

[@robinsonsauto]

It depends on the definition of bad, an open circuit, no it will stay open loop, sluggish would be hit and miss depending

[@Amopower]

That's fine, we can agree to disagree on this one. When you bench test an O2 with a torch, of course it will vary the voltage in response to you giving and taking fuel away. When the O2 is on the car, and you are in open loop, the amount of fuel it gets is constant and not being determined from the O2 signal, therefore it should be a flatline (unless you are playing with the throttle).

[@redinstrumental7535]

Thumbs up

[@cylinderTBLS]

What can cause the car to stay stuck in closed loop?

[@AamirZ]

Engines normally run rich when in open loop, when in closed loop its runs of sensors and doesn't burn as much fuel then.

[@tigeryoung3619]

👍👍👍

[@coffeefish]

Is this OBDII ?

[@jovanmrkaic9840]

What happen to part 2

[@nissanslut7870]

So if the data steam shows “open loop fault” on both banks, but also shows proper ect, why is there a fault? Is the sensor bad? I also had to replace the damned little plastic thing, maybe I switched the wires ?

[@MC-hs4mf]

Fuel system 1 CL Fuel System 2 N/A

[@buck187uga]

Would engine misfire 4 cylinder cause to stay open loop mode?

[@juketownrecords4297]

Did you get the anwser to this

[@blinkskaterkc]

I'd guess thermostat is stuck open, low coolant, or bad temp sensor

[@robinsonsauto]

cold engine = rich engine good chance your t-stat is stuck open, good assumption

[@billvillanueva6729]

question, why everytime a code sets like p0420 i am at idle and it says on my freeze frame data that I am running in open loop, even though I reach the operating temperature. I notice something too when i run and it sets a code my fuel system enters closed loop while running on my freeze frame data? does that mean that when my car is in idle my fuel system enters open loop, and when my car starts to run it enters closed loop?

[@zacharyredman8226]

bill villanueva did you ever figure out the problem. I am literally going through the same thing. Word for word.

[@083rt]

did you guys get a fix solution? Im having similar issues.

[@hookpaonline3349]

That I understand. But how to fix?

[@dblr616]

Thermostat or lying coolant temp sensor is the problem

[@jabaryad9358]

P1233 Ford

[@shirebands7169]

Only one bone to pick..... 14.7 to 1 not 14 to 7 to 1