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[quote=”ToyotaKarl” post=65358][quote=”Haloruler64″ post=65168][quote=”ToyotaKarl” post=65061]Eric, I am in complete agreement about finding the known problems, and you did find a vacuum leak indeed.
So did you seal up the leak (what someone was probably trying to do before when they glued it together) and flush, fill and bleed the cooling system?
I don’t know if you noticed but when you shot the video there were definite differences in the readings of the O2 sensors. O2S21 did not look like it was moving in a full range (as compared to O2S11). Now, I know that both upstream will never match but they should be fluctuating between .1 and .9. O2S21 did not appear to go below .295, where O2S11 went to .135. This would cause me to check the O2 sensors. Perhaps a different type (brand) of sensor was being used, or Bank 2 O2 sensor is getting lazy…. I know that not using DENSO O2 sensors on Toyotas can cause issues as well as mixing brands of O2 sensors.
I know I only saw a couple of seconds of the O2S21, so maybe it did move full range… Suppose we could get into the chicken and egg discussion that the O2 is richer because the Bank 2 LTFT was increased! :woohoo:
As always, thanks for all you do.. and disagreement isn’t disrespect!!
Karl![/quote]
O2 sensors don’t operate at full range when idling. To get an O2 sensor to switch properly, you’d need to rev the engine up to 2k RPM. That’s how I tested my O2 sensors. And even with a lazy O2 sensor, that wouldn’t cause start troubles. The O2 sensors don’t come into play until the ECU goes into closed loop, which is when the engine is warm.[/quote]
I am not talking about cold start difficulty… My point is about why one bank LTFT is at +5 and the other is at 0… The possible explanation… The video shows both O2 sensors readings and one is much more dynamic than the other….
🙂
Karl[/quote]
Oh, my apologies. I absolutely see what you mean. Yeah it could definitely be a partial issue with the O2 sensors, but a very minor one. Fuel trim of +5% is very small.
[quote=”theoldwizard1″ post=65762][quote=”EricTheCarGuy” post=65028]… Besides, the O2 is not active at cold start up anyway… [/quote]
[quote=”Haloruler64″ post=65168]…O2 sensors don’t operate at full range when idling. To get an O2 sensor to switch properly, you’d need to rev the engine up to 2k RPM.[/quote]
You guys are very “old school” with that kind of thinking !
An O2 sensor with a heater giving valid data very quickly (< 1-2 minutes) after startup, even at idle. This is the whole point of having a heater ! Even ScannerDanner commented in on of his videos how quickly this happened. The software will detect if the sensor is not properly responding and try to force it lean and then rich a couple of time before turning on the Check Engine light. If the O2 is not heated (older vehicles), then yes, a minute or so of high idle is required to get it to function. I don't understand the term "full range". EGO (O2) sensors "switches", changes from high to low or low to high voltage, when the exhaust gases pass stoichiometry. Some newer vehicles are now using heated "wide range"/analog/Universal EGO sensors that give a linear response (voltage proportional) over a range of air fuel ratios.[/quote] This is true, many O2 sensors have heaters. However, even heated, they still do not contribute to starting the car. That's the point I was trying to make. A CEL generally comes on when the fuel trim exceeds +/- 25% as far as I remember. Then it becomes a serious issue. My car had one that was +20% constantly, and it ended up being a vacuum leak. My O2 sensor was brand new, of course, so that didn't contribute. But you are very correct in what you're saying And about revving the car, that's not to warm it up. The O2 sensor is more active when the engine is under load. It's easier to see if it's "lazy" when at 2k RPM. This had nothing to do with heat. And about those wide band modern O2 sensors, I'd love one for myself 😀
[quote=”ToyotaKarl” post=65061]Eric, I am in complete agreement about finding the known problems, and you did find a vacuum leak indeed.
So did you seal up the leak (what someone was probably trying to do before when they glued it together) and flush, fill and bleed the cooling system?
I don’t know if you noticed but when you shot the video there were definite differences in the readings of the O2 sensors. O2S21 did not look like it was moving in a full range (as compared to O2S11). Now, I know that both upstream will never match but they should be fluctuating between .1 and .9. O2S21 did not appear to go below .295, where O2S11 went to .135. This would cause me to check the O2 sensors. Perhaps a different type (brand) of sensor was being used, or Bank 2 O2 sensor is getting lazy…. I know that not using DENSO O2 sensors on Toyotas can cause issues as well as mixing brands of O2 sensors.
I know I only saw a couple of seconds of the O2S21, so maybe it did move full range… Suppose we could get into the chicken and egg discussion that the O2 is richer because the Bank 2 LTFT was increased! :woohoo:
As always, thanks for all you do.. and disagreement isn’t disrespect!!
Karl![/quote]
O2 sensors don’t operate at full range when idling. To get an O2 sensor to switch properly, you’d need to rev the engine up to 2k RPM. That’s how I tested my O2 sensors. And even with a lazy O2 sensor, that wouldn’t cause start troubles. The O2 sensors don’t come into play until the ECU goes into closed loop, which is when the engine is warm.
[quote=”ToyotaKarl” post=65061]Eric, I am in complete agreement about finding the known problems, and you did find a vacuum leak indeed.
So did you seal up the leak (what someone was probably trying to do before when they glued it together) and flush, fill and bleed the cooling system?
I don’t know if you noticed but when you shot the video there were definite differences in the readings of the O2 sensors. O2S21 did not look like it was moving in a full range (as compared to O2S11). Now, I know that both upstream will never match but they should be fluctuating between .1 and .9. O2S21 did not appear to go below .295, where O2S11 went to .135. This would cause me to check the O2 sensors. Perhaps a different type (brand) of sensor was being used, or Bank 2 O2 sensor is getting lazy…. I know that not using DENSO O2 sensors on Toyotas can cause issues as well as mixing brands of O2 sensors.
I know I only saw a couple of seconds of the O2S21, so maybe it did move full range… Suppose we could get into the chicken and egg discussion that the O2 is richer because the Bank 2 LTFT was increased! :woohoo:
As always, thanks for all you do.. and disagreement isn’t disrespect!!
Karl![/quote]
O2 sensors don’t operate at full range when idling. To get an O2 sensor to switch properly, you’d need to rev the engine up to 2k RPM. That’s how I tested my O2 sensors. And even with a lazy O2 sensor, that wouldn’t cause start troubles. The O2 sensors don’t come into play until the ECU goes into closed loop, which is when the engine is warm.
[quote=”crypkilla” post=62989]hurray! and congratulations. this has been very educational. i’m now motivated to go outside and diagnose poor fuel econ on my 97 Ford Escort! maybe i’ll start a thread about it! thanks for the thorough and frequent updates![/quote]
It’s a pleasure providing these updates. Someone might find them useful. That hose below the EGR vacuum modulator valve is really inaccessible, many wouldn’t think to look there. Glad I noticed it.
And I’d suggest it! Though frustrating, it’s been a lot of fun. Plus the car will last a good while longer with new gaskets and a thorough cleaning inside the intake manifold.
[quote=”crypkilla” post=62989]hurray! and congratulations. this has been very educational. i’m now motivated to go outside and diagnose poor fuel econ on my 97 Ford Escort! maybe i’ll start a thread about it! thanks for the thorough and frequent updates![/quote]
It’s a pleasure providing these updates. Someone might find them useful. That hose below the EGR vacuum modulator valve is really inaccessible, many wouldn’t think to look there. Glad I noticed it.
And I’d suggest it! Though frustrating, it’s been a lot of fun. Plus the car will last a good while longer with new gaskets and a thorough cleaning inside the intake manifold.
I think this will be the last update. Cleaning the throttle body and fuel injectors helped the issue, but didn’t fix it. However, I decided to just drop $17 and get an intake manifold gasket kit. Replaced the intake manifold air chamber gasket, tightened it really well (it was a bit thicker than the original), and noticed that the pipe attached to the bottom of the EGR vacuum modulator valve was very loose. Replaced it with a new hose I had laying around and put tiny clamps on there to keep it firmly in place. Afterwards, I took it for two and a half hours of driving. The fuel trim stayed solid between +/-3 on the highway, occasionally going to +/-4. Rarely did it even reach +/-6.2. Even in rough uphill stop and go driving through a speed bump laden area, it did not go above 7.2%. Went really low only once, when I let go of the accelerator and braked and put it into park, spiked to -14% but didn’t go that low again (probably the IAC opening). All and all, I’m very happy. It’s not only acceptable, but very good.
Also, 26.5 MPG last fill up after a lot of idling and revving to test my various repairs. And a good amount of fuel lost to spilling (my fuel injector gasket broke and sprayed a substantial amount of fuel). I consider this a success! I wanted to thank all of you for helping and weighing in! It’s very much appreciated.
I think this will be the last update. Cleaning the throttle body and fuel injectors helped the issue, but didn’t fix it. However, I decided to just drop $17 and get an intake manifold gasket kit. Replaced the intake manifold air chamber gasket, tightened it really well (it was a bit thicker than the original), and noticed that the pipe attached to the bottom of the EGR vacuum modulator valve was very loose. Replaced it with a new hose I had laying around and put tiny clamps on there to keep it firmly in place. Afterwards, I took it for two and a half hours of driving. The fuel trim stayed solid between +/-3 on the highway, occasionally going to +/-4. Rarely did it even reach +/-6.2. Even in rough uphill stop and go driving through a speed bump laden area, it did not go above 7.2%. Went really low only once, when I let go of the accelerator and braked and put it into park, spiked to -14% but didn’t go that low again (probably the IAC opening). All and all, I’m very happy. It’s not only acceptable, but very good.
Also, 26.5 MPG last fill up after a lot of idling and revving to test my various repairs. And a good amount of fuel lost to spilling (my fuel injector gasket broke and sprayed a substantial amount of fuel). I consider this a success! I wanted to thank all of you for helping and weighing in! It’s very much appreciated.
[quote=”crypkilla” post=62316]Dude. First of all, watching STFT is stupid. Hitting 17% for a milisecond is irrelevant (and your scan tool cant even sample as fast as stft changes.)
Look at the average – aka LTFT.
Secondly. U think u have a vac leak? Do a propane enrichment test. And induce a small vac leak to see what a vac leak really does to fuel trims.
thirdly. Take advice like above comment and “mechanics” with a grain of salt. Trust hard evidence and published information.
The thing I sent u specificall says +- 20% is normal.[/quote]
Hey… you… stop being so right. Yeah I guess I’m stressing over nothing. I’ll do the propane enrichment this weekend most likely. Till then, I’ll watch long term fuel trim which is a bit wonky. Might reset the ECU and start fresh, because the first thing I taught it is revving high (checking for fuel injector leaks).
And engine is absolutely unmodified. Even has an OEM Toyota air filter in it.
[quote=”crypkilla” post=62316]Dude. First of all, watching STFT is stupid. Hitting 17% for a milisecond is irrelevant (and your scan tool cant even sample as fast as stft changes.)
Look at the average – aka LTFT.
Secondly. U think u have a vac leak? Do a propane enrichment test. And induce a small vac leak to see what a vac leak really does to fuel trims.
thirdly. Take advice like above comment and “mechanics” with a grain of salt. Trust hard evidence and published information.
The thing I sent u specificall says +- 20% is normal.[/quote]
Hey… you… stop being so right. Yeah I guess I’m stressing over nothing. I’ll do the propane enrichment this weekend most likely. Till then, I’ll watch long term fuel trim which is a bit wonky. Might reset the ECU and start fresh, because the first thing I taught it is revving high (checking for fuel injector leaks).
And engine is absolutely unmodified. Even has an OEM Toyota air filter in it.
I very much agree with the “visual learner” thing. I’ve always been great in school, but just reading instructions was difficult for me. My best classes were those with teachers that would show you how to do things instead of handing out sheets and waiting. That’s why I learned math so well: I have had a great streak of math teachers that were very involved but very tough.
My passion started the same as yours: I just wanted to take everything apart as a child. I took apart everything I could and tried to put it back together. This included the first computer I ever got. Thankfully, I put it back together right! I got into building computers, though with little money, I had to settle with upgrading instead of full on builds.
My family had two cars, one that they drove, and one that they left alone. Undriven for 5 years, no maintenance aside from tires for 8. When I got my license, I “inherited” this car. A 1996 Toyota Corolla, a rare example of a good looking Corolla of that year. The Corolla started acting up, never heated up right, and we were too poor to take it to a shop, so I took it upon myself. With no one to help, scared of taking anything apart in the engine bay for the first time, I replaced the thermostat.
Now I’ve been doing all the maintenance it needs by hand, occasionally helping out with other family cars. It’s my escape from the cruel world, when I’m upset or stuck in a bad place, I go out and work on the car. My father fixes home appliances for a living, so he knows a lot about mechanics, but he never fixed a car before. I use his set of tools and am slowly buying my own. It’s a good time.
I very much agree with the “visual learner” thing. I’ve always been great in school, but just reading instructions was difficult for me. My best classes were those with teachers that would show you how to do things instead of handing out sheets and waiting. That’s why I learned math so well: I have had a great streak of math teachers that were very involved but very tough.
My passion started the same as yours: I just wanted to take everything apart as a child. I took apart everything I could and tried to put it back together. This included the first computer I ever got. Thankfully, I put it back together right! I got into building computers, though with little money, I had to settle with upgrading instead of full on builds.
My family had two cars, one that they drove, and one that they left alone. Undriven for 5 years, no maintenance aside from tires for 8. When I got my license, I “inherited” this car. A 1996 Toyota Corolla, a rare example of a good looking Corolla of that year. The Corolla started acting up, never heated up right, and we were too poor to take it to a shop, so I took it upon myself. With no one to help, scared of taking anything apart in the engine bay for the first time, I replaced the thermostat.
Now I’ve been doing all the maintenance it needs by hand, occasionally helping out with other family cars. It’s my escape from the cruel world, when I’m upset or stuck in a bad place, I go out and work on the car. My father fixes home appliances for a living, so he knows a lot about mechanics, but he never fixed a car before. I use his set of tools and am slowly buying my own. It’s a good time.
Drove today, stopping once in a while to check on the fuel injectors not spraying. They’re dry. Stupid gaskets, returned a pack for being defective. Fuel trim wasn’t good, at one point hitting 14% in the city. After my trip, I decided to test the car how you asked me to. When fully warm and after 15 minutes of driving, I put it into park. Opened the hood, watched my phone for short term fuel trim, and saw that it was at 0-8%, mostly staying in the 4-8 range. When keeping it at 2,500 RPM, the STFT drops to +/-3, constantly switching between the two, which is normal. So it’s a vacuum leak. I can hear whistling, but I’m not sure if it’s a vacuum leak or just a squeaky belt. I can’t figured the freaking thing out.
Also, when driving and accelerating up to about 30 MPH, fuel trim does get high. When going a constant speed on the freeway, it’s fine. Sound like a vacuum leak to you? I don’t know, but I’m thoroughly frustrated.
Drove today, stopping once in a while to check on the fuel injectors not spraying. They’re dry. Stupid gaskets, returned a pack for being defective. Fuel trim wasn’t good, at one point hitting 14% in the city. After my trip, I decided to test the car how you asked me to. When fully warm and after 15 minutes of driving, I put it into park. Opened the hood, watched my phone for short term fuel trim, and saw that it was at 0-8%, mostly staying in the 4-8 range. When keeping it at 2,500 RPM, the STFT drops to +/-3, constantly switching between the two, which is normal. So it’s a vacuum leak. I can hear whistling, but I’m not sure if it’s a vacuum leak or just a squeaky belt. I can’t figured the freaking thing out.
Also, when driving and accelerating up to about 30 MPH, fuel trim does get high. When going a constant speed on the freeway, it’s fine. Sound like a vacuum leak to you? I don’t know, but I’m thoroughly frustrated.