P0171 p0174 p2196 p2198
#19
Lexus Test Driver
^^^
Thank you for this info.
In all honesty, your trims are almost perfect at idle.
MAF readings are also good.
O2 sensor fluctuations are sound.
Only thing im not seeing here iare the AF voltages.
I see a O2S1 and O2S5 both at 1.0v.
Those could be AF FT voltage. (1.0v is actually good)
Im looking for AFS voltage.
Value of around 3.30v at idle at each bank.
See if you have this data.
One more thing, when you get these LEAN codes, can your scanner see the freeze frame?
That would be helpful as well.
Thank you for this info.
In all honesty, your trims are almost perfect at idle.
MAF readings are also good.
O2 sensor fluctuations are sound.
Only thing im not seeing here iare the AF voltages.
I see a O2S1 and O2S5 both at 1.0v.
Those could be AF FT voltage. (1.0v is actually good)
Im looking for AFS voltage.
Value of around 3.30v at idle at each bank.
See if you have this data.
One more thing, when you get these LEAN codes, can your scanner see the freeze frame?
That would be helpful as well.
#20
Intermediate
The MAF is reading roughly double correct Air Flow Rate the voltage swings are too exaggerated. Your Sensor codes are set and you’ve cleaned these codes before with CRC on the MAF. You’ve got an oiled Intake Air Filter (booo...) coating the entire Air Intake System; Air Box, MAF, Air Tubes and the Throttle Body coated in this stuff. These components are designed to be operated bone dry and clean. Clean them and remove the Throttle Body and clean it in hand. Not hard. The back side of the butterfly gets absolutely filthy.
Your O2 Sensors aren’t broken and they’re trying to keep up, but they’re doomed to fail or go “suspect” soon because of fake readings.
While you’re doing some low cost maintenance, change your PCV valve. Since this component is on most every list of items to check in P0171 code readings and is one of the items that often gets neglected, spending $10 on a new one isn’t throwing parts. IMO, everything is pointing towards the common point of the Air/Fuel Intake System.
When you’ve got it cleaned up and back to a dry air filter, clear your codes and take a ride. Your Fuel Trim levels will relearn themselves as you drive and hopefully your lights will stay off.
Last edited by Richardsr; 01-17-19 at 07:59 PM.
#21
Lexus Test Driver
My apologies if i missed it.
All i see is the fluctuation of flow read by the MAF.
High -- 2.92g/sec.
Low -- 2.87g/sec.
Thats just a 0.05 g/sec. difference.
#22
Intermediate
Data values for 2002 (1MZ-FE, engine at proper operating temp)
Note: this may be comparing apples and oranges due to 2005 was 3MZ-FE
CALC LOAD Idling: 13.1 − 18.7 %, Racing without load(2,500 rpm): 11.7 − 17.3 %
MAF Idling: 3.3 − 4.7 gm/sec. Racing without load (2,500 rpm):10.4 − 15.4 gm/sec
ENG SPD Idling: 650 − 750 rpm
The first photo looks like freeze frame trigger event
Eng Load 49%
2615 RPM
54 Km/h (33mph)
LTFT Bank 1 39.84% with STFT -4.69%
LTFT Bank 2 41.41% with STFT -2.34%
Take a snapshot of this data at 2500 RPM, vehicle in park, no load
Also did you look at the TSB that was noted above? And does your vehicle fall into the criteria listed ( ES 330 vehicles produced BEFORE the Production Change*Effective VIN shown)?
Note: this may be comparing apples and oranges due to 2005 was 3MZ-FE
CALC LOAD Idling: 13.1 − 18.7 %, Racing without load(2,500 rpm): 11.7 − 17.3 %
MAF Idling: 3.3 − 4.7 gm/sec. Racing without load (2,500 rpm):10.4 − 15.4 gm/sec
ENG SPD Idling: 650 − 750 rpm
The first photo looks like freeze frame trigger event
Eng Load 49%
2615 RPM
54 Km/h (33mph)
LTFT Bank 1 39.84% with STFT -4.69%
LTFT Bank 2 41.41% with STFT -2.34%
Take a snapshot of this data at 2500 RPM, vehicle in park, no load
Also did you look at the TSB that was noted above? And does your vehicle fall into the criteria listed ( ES 330 vehicles produced BEFORE the Production Change*Effective VIN shown)?
#23
Intermediate
My bad. Long day, late hours and my old ECM was suffering from too much TMI. I did respond last night, but never hit the “Submit” button and when I hit it this morning, my internet posting session had timed out, so here I am for a bit.
Basically, the MAF g/sec rate goes from OK at Idle to double the engineered rate at 2500 rpms. 2 - 7 g/sec is good at Idle (600 rpms), but at 2500 rpms it should be between 15 - 25 g/sec. See Fortitude’s Post #22.
The Short Term Trim Rates for both banks by the O2s indicates more gas is being injected to “fix” the lean condition. In positive corrections, fuel is added to adjust for a lean condition, while negative corrections respond to a rich react very quickly to O2 sensor input.
The Long Term Trim Rates are roughly twice the normal and high Positive Trims/positive fuel corrections can be traced to MAF and O2 sensor faults, vacuum leaks from intake gaskets/hoses, unmetered air (intake snorkel leak), clogged or dirty fuel injectors, fuel delivery issues and even a clogged catalytic converter.
In positive corrections, fuel is added to adjust for a lean condition, while negative corrections respond to a rich condition. STFT corrections represent and react very quickly to O2 sensor input. If you were to create a large vacuum leak and disconnect the PCV hose, the computer would immediately add positive fuel trim to balance the mixture. Short Term Fuel Trim is not stored in Keep Alive Memory (KAM) in the ECM after shut down and automatically resets to 0 for the next start/run cycle.
I agree with your question as to why AF Sensors aren’t considered more than they are in these articles. And given this car has 178K on it, it’s a valid concern. Maybe because the Air Intake System doesn’t get enough “user maintenance” and they tend to go bad first(?). Take the car in question here... It has a K&N oiled Air Filter and they’re getting a baaad name for funking up not only MAFs everywhere, but now it’s from the Air Box all the way to the injectors with their goo. The car here has no mention of maintenance history other than cleaning the MAF to clear out a P0171 code a time or two and a P0174 code following along soon(?).
Your recommendation in Post #5 is where we’re at... Time to get our hands dirty and this is cheap and easy stuff.
1. Get rid of K&N Air Filter and replace with Genuine OEM.
2. Clean the Air Box and Air tube with Ammonia-free Windex.
3. Remove MAF and clean with CRC.
4. Clean inside the MAF mounting area.
5. Remove Throttle Body and clean with Carb Cleaner and thoroughly rinse after with CRC.
6. Spend $10 and change out often neglected PCV valve with Genuine OEM.
7. Spend $15 more and change out neglected Fuel Filler Cap with Genuine OEM, be sure to silicon spray the rubber sealer gasket first.
Do these things and get back with us, please.
Thanks to mirekti for the pictures and thanks to Fortitude for the read out.
Cheers
Last edited by Richardsr; 01-18-19 at 08:08 PM. Reason: Info
#24
Pit Crew
Thread Starter
Update
Guys, first of all all thanks goes to you. I really appreciate all the effort.
I am not sure what to say right now. It’s been three days since I haven’t received any codes, and they’ve been coming within hours after clearing them in the last two weeks.
So far I have only replaced the tank cap. MAF sensor arrived few days bac, but I still havent replaced it as I was waiting for the OEM air filter. PCV is supposed to be delivered today.
I will certainly replace PCV, but not sure about the MAF and K&N filter anymore. It’s been rather cold last two days here. This makes me think one of my hoses might leak and now, because it is cold, they shrinked and the codes don’t show up (just the flow of my thoughts, not that I am certain this is happening).
Oh, there’s one more thing. My wife had been driving the car last three weeks too, and it happened that she had ended up at a gas station each time the car needed gas. For some reason she was not pouring Premium gas, but Regular and the one in between. Could that have been the cause for lean codes? I only found this out two days ago by chance, and aprat from the colder weather the car runs on Premium since Friday, and no error codes.
I will keep you posted.
I am not sure what to say right now. It’s been three days since I haven’t received any codes, and they’ve been coming within hours after clearing them in the last two weeks.
So far I have only replaced the tank cap. MAF sensor arrived few days bac, but I still havent replaced it as I was waiting for the OEM air filter. PCV is supposed to be delivered today.
I will certainly replace PCV, but not sure about the MAF and K&N filter anymore. It’s been rather cold last two days here. This makes me think one of my hoses might leak and now, because it is cold, they shrinked and the codes don’t show up (just the flow of my thoughts, not that I am certain this is happening).
Oh, there’s one more thing. My wife had been driving the car last three weeks too, and it happened that she had ended up at a gas station each time the car needed gas. For some reason she was not pouring Premium gas, but Regular and the one in between. Could that have been the cause for lean codes? I only found this out two days ago by chance, and aprat from the colder weather the car runs on Premium since Friday, and no error codes.
I will keep you posted.
UPDATE: P0171 and P0174 came back this morning. It seems the show goes on
Last edited by mirekti; 01-21-19 at 10:02 AM.
#25
Lexus Test Driver
Hey, no worries man.
I actually had to squint down the data to check it myself. Lol.
You're absolutely right, TMI is better than no information.
#26
Lexus Test Driver
Guys, first of all all thanks goes to you. I really appreciate all the effort.
I am not sure what to say right now. It’s been three days since I haven’t received any codes, and they’ve been coming within hours after clearing them in the last two weeks.
So far I have only replaced the tank cap. MAF sensor arrived few days bac, but I still havent replaced it as I was waiting for the OEM air filter. PCV is supposed to be delivered today.
I will certainly replace PCV, but not sure about the MAF and K&N filter anymore. It’s been rather cold last two days here. This makes me think one of my hoses might leak and now, because it is cold, they shrinked and the codes don’t show up (just the flow of my thoughts, not that I am certain this is happening).
Oh, there’s one more thing. My wife had been driving the car last three weeks too, and it happened that she had ended up at a gas station each time the car needed gas. For some reason she was not pouring Premium gas, but Regular and the one in between. Could that have been the cause for lean codes? I only found this out two days ago by chance, and aprat from the colder weather the car runs on Premium since Friday, and no error codes.
I will keep you posted.
I am not sure what to say right now. It’s been three days since I haven’t received any codes, and they’ve been coming within hours after clearing them in the last two weeks.
So far I have only replaced the tank cap. MAF sensor arrived few days bac, but I still havent replaced it as I was waiting for the OEM air filter. PCV is supposed to be delivered today.
I will certainly replace PCV, but not sure about the MAF and K&N filter anymore. It’s been rather cold last two days here. This makes me think one of my hoses might leak and now, because it is cold, they shrinked and the codes don’t show up (just the flow of my thoughts, not that I am certain this is happening).
Oh, there’s one more thing. My wife had been driving the car last three weeks too, and it happened that she had ended up at a gas station each time the car needed gas. For some reason she was not pouring Premium gas, but Regular and the one in between. Could that have been the cause for lean codes? I only found this out two days ago by chance, and aprat from the colder weather the car runs on Premium since Friday, and no error codes.
I will keep you posted.
UPDATE: P0171 and P0174 came back this morning. It seems the show goes on
Thats awesome.
Yea, looking at the data you sent didnt indicate any abnormalities to me.
It wouldve been nice to see the AF voltages at idle.
Anyways, i actually got data on my own vehicle with has a 1MZ just to compare.
If your issue does come back, hopefully not, everyone here will be able to help.
#27
Intermediate
Guys, first of all all thanks goes to you. I really appreciate all the effort.
I am not sure what to say right now. It’s been three days since I haven’t received any codes, and they’ve been coming within hours after clearing them in the last two weeks.
So far I have only replaced the tank cap. MAF sensor arrived few days bac, but I still havent replaced it as I was waiting for the OEM air filter. PCV is supposed to be delivered today.
I will certainly replace PCV, but not sure about the MAF and K&N filter anymore. It’s been rather cold last two days here. This makes me think one of my hoses might leak and now, because it is cold, they shrinked and the codes don’t show up (just the flow of my thoughts, not that I am certain this is happening).
Oh, there’s one more thing. My wife had been driving the car last three weeks too, and it happened that she had ended up at a gas station each time the car needed gas. For some reason she was not pouring Premium gas, but Regular and the one in between. Could that have been the cause for lean codes? I only found this out two days ago by chance, and aprat from the colder weather the car runs on Premium since Friday, and no error codes.
I will keep you posted.
I am not sure what to say right now. It’s been three days since I haven’t received any codes, and they’ve been coming within hours after clearing them in the last two weeks.
So far I have only replaced the tank cap. MAF sensor arrived few days bac, but I still havent replaced it as I was waiting for the OEM air filter. PCV is supposed to be delivered today.
I will certainly replace PCV, but not sure about the MAF and K&N filter anymore. It’s been rather cold last two days here. This makes me think one of my hoses might leak and now, because it is cold, they shrinked and the codes don’t show up (just the flow of my thoughts, not that I am certain this is happening).
Oh, there’s one more thing. My wife had been driving the car last three weeks too, and it happened that she had ended up at a gas station each time the car needed gas. For some reason she was not pouring Premium gas, but Regular and the one in between. Could that have been the cause for lean codes? I only found this out two days ago by chance, and aprat from the colder weather the car runs on Premium since Friday, and no error codes.
I will keep you posted.
UPDATE: P0171 and P0174 came back this morning. It seems the show goes on
Glad you replaced the Gas Cap and hope it was a Genuine OEM part? Spray some silicon spray on the cap’s rubber washers.
I run premium gas gas because my car runs better, has more pep when I want it and premium gas generally contains more cleaning additives than regular. Here’s a tip: Get a 6oz bottle of Gumout® Regane® High Mileage Fuel System Cleaner and add it to your gas every 3 - 5,000 miles. Good stuff.
Keep us posted.
#28
Driver School Candidate
You need to diagnose the lean codes first.
Lets back up here.
Your previous post, you had just the P0174 once a year. Bank 2
Im assuming you didnt fix this and kept blowing the code.
Then it got more frequent.
Then you now have both P0174 and P0171.(both banks)
So those 2 codes didnt just pop up at the same time., per OP.
If you didnt solve your original 174, I suggest grab a OBD scanner and see what your fuel trims and AF voltages before you replace parts that you might not need.
If your cranking 180k miles and your A/F sensors are original, thats where i would look.
I vaguely remember there was a TSB for these codes and they point to failed A/F sensors.
Found it:
http://media.fixed-ops.com/Lex_Servi...s/eg019l05.pdf
Hope this will get you in the right direction.
Lets back up here.
Your previous post, you had just the P0174 once a year. Bank 2
Im assuming you didnt fix this and kept blowing the code.
Then it got more frequent.
Then you now have both P0174 and P0171.(both banks)
So those 2 codes didnt just pop up at the same time., per OP.
If you didnt solve your original 174, I suggest grab a OBD scanner and see what your fuel trims and AF voltages before you replace parts that you might not need.
If your cranking 180k miles and your A/F sensors are original, thats where i would look.
I vaguely remember there was a TSB for these codes and they point to failed A/F sensors.
Found it:
http://media.fixed-ops.com/Lex_Servi...s/eg019l05.pdf
Hope this will get you in the right direction.
#30
Lead Lap
iTrader: (1)
Get an OBD2 scanner that can read live data for your A/F sensors. I recommend BlueDriver on Amazon or Techstream software.
If your car is California spec, you’ll have A/F sensors that go between 0-5volts. 3.3volts is ideal. If it’s Federal spec, you’ll have regular O2 sensors that are between 0.1 and 0.9 volts, middle point is normal. Get the engine coolant up to 180F. Observe your voltage readings.
For A/F sensors, low voltage is rich.
For O2 sensors, high voltage is rich.
Now unplug a vacuum line to create a lean condition and watch the voltage. If the sensors don’t react, there is your problem. If they respond properly, then you actually have a Rich condition that you need to fix.
If your car is California spec, you’ll have A/F sensors that go between 0-5volts. 3.3volts is ideal. If it’s Federal spec, you’ll have regular O2 sensors that are between 0.1 and 0.9 volts, middle point is normal. Get the engine coolant up to 180F. Observe your voltage readings.
For A/F sensors, low voltage is rich.
For O2 sensors, high voltage is rich.
Now unplug a vacuum line to create a lean condition and watch the voltage. If the sensors don’t react, there is your problem. If they respond properly, then you actually have a Rich condition that you need to fix.
Last edited by Hayk; 04-07-21 at 07:04 PM.