Stuck in Open Loop
Ok so Open loop is basically when the PCM is not adjusting fuel trims based on inputs.
Closed loop operation is when the PCM is adjusting fuel trims based on it's inputs, which are numerous I might add.
The O2's are heavily relied upon for closed loop operation, since they are, in effect the PCM's way to monitor the combustion process, a/f mixture and so on.
P0125, is, a coolant temp code, perhaps you meant to write p0135? The 135 is an O2 heater ckt code. Either way the vehicle is going to stay in open loop.
Being in open loop isn't necessarily going to make the engine go into some sort of "default full rich or full lean condition". Your PCM just isn't going to be able to address any other problems related to fuel delivery as efficiently if at all. Honest truth, I've never monitored a vehicle after, not fixing, an issue like this. Curious to see what the fuel trims will do if another fuel control issue were to arise.
Hope this helps...
Closed loop operation is when the PCM is adjusting fuel trims based on it's inputs, which are numerous I might add.
The O2's are heavily relied upon for closed loop operation, since they are, in effect the PCM's way to monitor the combustion process, a/f mixture and so on.
P0125, is, a coolant temp code, perhaps you meant to write p0135? The 135 is an O2 heater ckt code. Either way the vehicle is going to stay in open loop.
Being in open loop isn't necessarily going to make the engine go into some sort of "default full rich or full lean condition". Your PCM just isn't going to be able to address any other problems related to fuel delivery as efficiently if at all. Honest truth, I've never monitored a vehicle after, not fixing, an issue like this. Curious to see what the fuel trims will do if another fuel control issue were to arise.
Hope this helps...
Are all of your O2 sensors bad? Technically the car only needs one working O2 sensor to operate the engine. It will throw all kinds of codes but the car will still run. Toyota built so many damn failsafes intho the ECU that it can run with many malfunctioning sensors. It's actually a very smart system, so smart in fact that it fights many people who try to turbo their cars 
Unless you know how to tune around it that is 
Unless you know how to tune around it that is 
no just one...ish lol Its kind of a weird problem...but i didnt know just one would still run the car...I guess thats why it was going into closed loop yesterday..lol I talked to my instructor and he basically said running in open loop was fine because 02's are mainly an emissions related thing, and the car will run fine off the fuel maps just as long as all my other sensors are working.
I don;t want to get into a war over this but please know what you are talking about and not guess.
So here we go again ,o2's are used by the ecu to determine fuel maps .
Once the specified temp in the mapping is reached it will then start to monitor the o2's which have been artificially heated by the heater circuit to provide a correct reading.
I know this because i am a trained technician not from a high school course. 2ND because i own all of my cars factory manuals and third because i have a live data feed through obd2 running in my car 100% of the time so it shows me all the o2 ,temp and trim values all day.
Stop with the guessing an confusing people who don't know.
If this is the kind of info you are being given find a new source . That is a 1980's mechanics response who thinks they are magical. Not a a technicians response to the question by far ,sorry.
I don;t want to get into a war over this but please know what you are talking about and not guess.
So here we go again ,o2's are used by the ecu to determine fuel maps .
Once the specified temp in the mapping is reached it will then start to monitor the o2's which have been artificially heated by the heater circuit to provide a correct reading.
I know this because i am a trained technician not from a high school course. 2ND because i own all of my cars factory manuals and third because i have a live data feed through obd2 running in my car 100% of the time so it shows me all the o2 ,temp and trim values all day.
Stop with the guessing an confusing people who don't know.
I don;t want to get into a war over this but please know what you are talking about and not guess.
So here we go again ,o2's are used by the ecu to determine fuel maps .
Once the specified temp in the mapping is reached it will then start to monitor the o2's which have been artificially heated by the heater circuit to provide a correct reading.
I know this because i am a trained technician not from a high school course. 2ND because i own all of my cars factory manuals and third because i have a live data feed through obd2 running in my car 100% of the time so it shows me all the o2 ,temp and trim values all day.
Stop with the guessing an confusing people who don't know.
If this is the kind of info you are being given find a new source . That is a 1980's mechanics response who thinks they are magical. Not a a technicians response to the question by far ,sorry.
I don;t want to get into a war over this but please know what you are talking about and not guess.
So here we go again ,o2's are used by the ecu to determine fuel maps .
Once the specified temp in the mapping is reached it will then start to monitor the o2's which have been artificially heated by the heater circuit to provide a correct reading.
I know this because i am a trained technician not from a high school course. 2ND because i own all of my cars factory manuals and third because i have a live data feed through obd2 running in my car 100% of the time so it shows me all the o2 ,temp and trim values all day.
Stop with the guessing an confusing people who don't know.
I don;t want to get into a war over this but please know what you are talking about and not guess.
So here we go again ,o2's are used by the ecu to determine fuel maps .
Once the specified temp in the mapping is reached it will then start to monitor the o2's which have been artificially heated by the heater circuit to provide a correct reading.
I know this because i am a trained technician not from a high school course. 2ND because i own all of my cars factory manuals and third because i have a live data feed through obd2 running in my car 100% of the time so it shows me all the o2 ,temp and trim values all day.
Stop with the guessing an confusing people who don't know.
A. I'm in my third year of college at an automotive technical university
B. I have all the factory manuals for my car, and obd2 running 24/7 in my car as well.
C. The instructor I was referring to was the one who teaches the electrical and modern automotive concepts part of our course, so if any of my teachers knew what they were talking about, it would be him.
D. He was NOT condoning me wanting to run in open loop, he just said that "if" I did, I wasn't going to "blow up" my car, or ruin the engine, or anything except the cats for that matter; like ppl on here have suggested.
E. I agree with what you said 02's do...but I think a more accurate way of explaining it is... The ECM has a base (rich) map for running cold/if anything went bad it would have something to refer to, in order to keep the car running, but I think everyone on here knows that. The oxygen sensors "determine" or "alter" the base (rich) factory fuel map to run around or at 14.7 AFR which is NOT some "magical engines running perfect number" (a fact to back that up is that when you floor it, you go into open loop which runs it just a tad richer for BETTER PERFORMANCE), it IS however an environmental standard, and anyone that knows cars knows that a car will run a little better a tad richer, but the government doesn't care about that, they care about the gas mileage/emission..etc.
So my point is...yes 02's are important, but they are mainly emissions related, and yes the car will run fine without them, just a tad rich.
So please don't say I'm just "guessing", I do know what I'm talking about.
Oh, and I'm not in the least suggesting that anyone run in open loop all the time if given the choice, but to fix my car back to perfect closed loop working order, I would have to spend hundreds that I don't have...that's the only reason I'm doing it.
Last edited by fordsvtmfl; Jul 16, 2009 at 02:50 PM.
ford seriously then , with all the info of you not being a tech but at an auto college ( if i read between the lines of what you are not saying ) why do you need a free forum ,should you not already know how to fix it especially if you are running a data logger to know where your problem is that will not take $1000's to fix .
Sorry your answers and your knowledge don't jive.
Sorry your answers and your knowledge don't jive.
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