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Bank 2 lean condition? Need some insight please!!!
What's up guys so I have had this concern for 2 years since I bought the car... I kinda just avoid this rpm so I dont run into this problem... the issue I have is around 2200 rpm car has a "misfire hiccup" any other rpm range car is fine does it sometimes around 1500 rpm too only those 2 set rpms... car is a ls1 with a mp112 blower lingenfelter custom cam 9.5 compression pistons, long tube headers had 42 lb injectors "same issue before now has 80lb injectors same issue..." since then I have put a 50/50 meth kit and nitrous so if I rev engine to 2200 rpm bank 1 stft stays good at -1.4 with 02 sensor voltage at .9 bank 2 how ever will go to .2 volts and stft will be +30 afr on bank 2 will go up to 22 afr vac is at 15 to 20 have done smoke test with no found leaks only real issue is when I fill up the tank to full I can smell the fumes when the car is parked... that's it... I even double gasket the headers on the head... here is the video link of my issue
https://youtu.be/1lJftiwsDiw
I just watched your video and noticed your bank 2 sensor 1 is reporting WAY rich...it looks like it’s pegged out at 960-970 MV at idle....do you have post cat O2 sensors ??...I look at LTFT (because the purpose of long term is to keep the short term near “stoic”) in this case but in your case I’m sure your LTFT on bank 2 would be -20 to -30 (BUT IN YOUR CASE THE STFL IS +26 AT HIGHER RPM) ...pull your brake booster hose at idle and see if the millivoltage signal decreases bank 2 sensor 1...if it doesn’t that O2 sensor is bad !!...if it does decrease you really do have a rich condition !!...can you do a video with your 02 sensors and fuel trims at idle and at 2500 rpm...would just like to look at it !!...that bank 2 sensor 1 should be switching between 200-800 millivolts !!... this is what mine look look at on idle !!
I just watched your video and noticed your bank 2 sensor 1 is reporting WAY rich...it looks like it’s pegged out at 960-970 MV at idle....do you have post cat O2 sensors ??...I look at LTFT (because the purpose of long term is to keep the short term near “stoic”) in this case but in your case I’m sure your LTFT on bank 2 would be -20 to -30 (BUT IN YOUR CASE THE STFL IS +26 AT HIGHER RPM) ...pull your brake booster hose at idle and see if the millivoltage signal decreases bank 2 sensor 1...if it doesn’t that O2 sensor is bad !!...if it does decrease you really do have a rich condition !!...can you do a video with your 02 sensors and fuel trims at idle and at 2500 rpm...would just like to look at it !!...that bank 2 sensor 1 should be switching between 200-800 millivolts !!... this is what mine look look at on idle !!
hey the sensors are new sensors... and the voltage at any other rpm would read fine and ltft have been disabled dont have 02 sensors in the rear I'll try that vac test leak to verify
Did you buy OEM O2 sensors ??... if not it’s most likely a bad sensor...try that test and create a vacuum leak...if that sensor still remains high (900 Mv) the sensor is not responding to a lean condition...with your scan tool connected do you read anywhere from 350-550 millivolts..(engine cold) on the O2 sensors ??...GM have a bias voltage and the PCM sends out about 450 MV to monitor the sensor circuit but the FSM says from 350-550 is good. Let’s do the “O2 response test” and we will go from there
Did you buy OEM O2 sensors ??... if not it’s most likely a bad sensor...try that test and create a vacuum leak...if that sensor still remains high (900 Mv) the sensor is not responding to a lean condition...with your scan tool connected do you read anywhere from 350-550 millivolts..(engine cold) on the O2 sensors ??...GM have a bias voltage and the PCM sends out about 450 MV to monitor the sensor circuit but the FSM says from 350-550 is good. Let’s do the “O2 response test” and we will go from there
I want to thank you again for helping me out... so on a cold start the sensors are reading .005 I believe. I have the video and when revved on a cold start go to 1.0xx .9 is the highest it should be if I can remember right, here is the video after reaching operating temp.
https://youtu.be/FFZAnJooCrc
Did you buy OEM O2 sensors ??... if not it’s most likely a bad sensor...try that test and create a vacuum leak...if that sensor still remains high (900 Mv) the sensor is not responding to a lean condition...with your scan tool connected do you read anywhere from 350-550 millivolts..(engine cold) on the O2 sensors ??...GM have a bias voltage and the PCM sends out about 450 MV to monitor the sensor circuit but the FSM says from 350-550 is good. Let’s do the “O2 response test” and we will go from there
[QUOTE=Felix Olivera;1597601122]I want to thank you again for helping me out... so on a cold start the sensors are reading .005 I believe. I have the video and when revved on a cold start go to 1.0xx .9 is the highest it should be if I can remember right, here is the video after reaching operating temp.
By looking at this video BOTH banks are running RICH !!...I don’t work on many cars that don’t have post cat O2 sensors like yours...I need to look at LTFT to diagnose these problems...I read your initial thread and you said you have a strong smell of gas after you fill up... you could have a stuck open EVAP purge valve/solenoid...this will give you a rich condition...all that fuel vapors are going into the intake manifold...is the car hard to start with that rich initial condition after fill up ???....you said you have a smoke machine ??...he’ll, I don’t even have one but I have everything else...don’t know if I want to shell out a few grand for one !!...so look at that evap purge valve... it might be stuck open !....pic enclosed...left hand fuel rail area...can't miss it !!...under the hood all the lines are hard so you can't pinch it off....probably somewhere near the fuel tank...or remove the valve and see if you can blow through it or use your smoke machine !!...good luck !!
Is this just KOEO ??...key on engine off ??...looks like you have 30 and 25 millivolts there !!...should be higher but I don't know how accurate your scan tool is !!
I want to thank you again for helping me out... so on a cold start the sensors are reading .005 I believe. I have the video and when revved on a cold start go to 1.0xx .9 is the highest it should be if I can remember right, here is the video after reaching operating temp. https://youtu.be/FFZAnJooCrc
By looking at this video BOTH banks are running RICH !!...I don’t work on many cars that don’t have post cat O2 sensors like yours...I need to look at LTFT to diagnose these problems...I read your initial thread and you said you have a strong smell of gas after you fill up... you could have a stuck open EVAP purge valve...this will give you a rich condition...all that fuel vapors are going into the intake manifold...is the car hard to start with that rich initial condition ???....you said you have a smoke machine ??...he’ll, I don’t even have one but I have everything else...don’t know if I want to shell out a few grand for one !!...so look at that evap purge valve... it might be stuck open !....pic enclosed...left hand fuel rail area...can't miss it !!...under the hood all the lines are hard so you can't pinch it off....probably somewhere near the fuel tank !!
Is this just KOEO ??...key on engine off ??...looks like you have 30 and 25 millivolts there !!...should be higher but I don't know how accurate your scan tool is !!
I tested on right before on an oldsmobile and read .450 engine cold key on engine off
I want to thank you again for helping me out... so on a cold start the sensors are reading .005 I believe. I have the video and when revved on a cold start go to 1.0xx .9 is the highest it should be if I can remember right, here is the video after reaching operating temp. https://youtu.be/FFZAnJooCrc
By looking at this video BOTH banks are running RICH !!...I don’t work on many cars that don’t have post cat O2 sensors like yours...I need to look at LTFT to diagnose these problems...I read your initial thread and you said you have a strong smell of gas after you fill up... you could have a stuck open EVAP purge valve/solenoid...this will give you a rich condition...all that fuel vapors are going into the intake manifold...is the car hard to start with that rich initial condition after fill up ???....you said you have a smoke machine ??...he’ll, I don’t even have one but I have everything else...don’t know if I want to shell out a few grand for one !!...so look at that evap purge valve... it might be stuck open !....pic enclosed...left hand fuel rail area...can't miss it !!...under the hood all the lines are hard so you can't pinch it off....probably somewhere near the fuel tank...or remove the valve and see if you can blow through it or use your smoke machine !!...good luck !!
my engine is modified with an mp112 blower I'd have to see where the purge solenoid is located... and after complete full up the car starts right up... I know the condition you speak of cars that come in to the dealer with a purge stuck open have a hard time starting after fill up
my engine is modified with an mp112 blower I'd have to see where the purge solenoid is located... and after complete full up the car starts right up... I know the condition you speak of cars that come in to the dealer with a purge stuck open have a hard time starting after fill up
THAT'S RIGHT...you said you had a blower !!...well, now we know the car is actually running rich it's time to start diagnosing and getting data...could be: bad ECT sensor (car thinks the coolant temp is still low and it richens the mixture), fuel pump, MAP/MAF, leaking Injector, plugged exhaust. Just trying to figure out why you have that strong fuel smell after fill up...did you look around the fuel tank ??
THAT'S RIGHT...you said you had a blower !!...well, now we know the car is actually running rich it's time to start diagnosing and getting data...could be: bad ECT sensor (car thinks the coolant temp is still low and it richens the mixture), fuel pump, MAP/MAF, leaking Injector, plugged exhaust. Just trying to figure out why you have that strong fuel smell after fill up...did you look around the fuel tank ??
have not seen any fuel leaks just checked car it does have the purge valve on there and it is not stuck open cannot blow air through it or suck from it "kinda like my ex, hence why she is my ex.." lol jokes aside also observed something else.. hooked up the scanner found both sensor voltage when first turnig key on car off, .200 volts and slowly drop to .015 and .020 they are losing voltage!?!? What could cause that? And the scanner is reading correctly doing the test on another vehicle voltage stays at .450 also it's a 4 wire sensor on my vette thanks again!
THAT'S RIGHT...you said you had a blower !!...well, now we know the car is actually running rich it's time to start diagnosing and getting data...could be: bad ECT sensor (car thinks the coolant temp is still low and it richens the mixture), fuel pump, MAP/MAF, leaking Injector, plugged exhaust. Just trying to figure out why you have that strong fuel smell after fill up...did you look around the fuel tank ??
have not seen any fuel leaks just checked car it does have the purge valve on there and it is not stuck open cannot blow air through it or suck from it "kinda like my ex, hence why she is my ex.." lol jokes aside also observed something else.. hooked up the scanner found both sensor voltage when first turnig key on car off, .200 volts and slowly drop to .015 and .020 they are losing voltage!?!? What could cause that? And the scanner is reading correctly doing the test on another vehicle voltage stays at .450 also it's a 4 wire sensor on my vette thanks again!
Try disconnecting the O2 sensor harness both sides and read the bias voltage again from the scan tool !!
Try disconnecting the O2 sensor harness both sides and read the bias voltage again from the scan tool !!
quick update I monitored the 02 sensors voltage while driving the car normal, and voltages on both sensors do fluctuate from .2 to .8 still haven't had the chance to disconnect sensors and see results
If the O2 switches between between .200-.800 Mv that’s perfect !!..,no need to disconnect the harness !!
so I went ahead and disconnected the 02 sensor passanger side anyways and when I did the voltage went up to .450 soon as I connect it starts slowly dropping back down to .005 even .000
Can you try it with a multimeter instead of your scan tool ??...how long does it take to drop down ??. When I checked mine I checked the voltage got my reading and removed the test leads. Like I said if your driving and the O2 are switching between .200-.800 Mv that's normal operation !!...the only reason I can see it dropping is because you are measuring such LOW voltages that the normally high impedance of the meters drag the voltage down. The perfect mutimeter would have 0 impedance meaning it will draw no current from the circuit that is being tested. The more current a voltmeter draws from a circuit under load the more the measured voltage will decrease. That is the only thing I can think of !!...Maybe someone can chime in !!
07-14-2018, 03:33 PM
Bank 2 lean condition? Need some insight please!!!
