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Sure thing. I will redo the test with those items. I DO have a propane torch. I believe I kept the MAF that I took out. (That’s what you’re asking, right?) I had JUST replaced it. I also did the catalytic converter and downstream O2 a week before that. One thing I DO notice while driving it is the takeoff from a stoplight. It wants to slightly hesitate, almost like it will stall- but only a blip, if that makes sense.
Last edited by coupdeaccord; Oct 13, 2023 at 11:41 AM.
You are right. I'm asking if you kept the MAF in case the new one was bad out of the box. It happens and can complicate a diagnosis.
great! I was JUST typing this, adding it to the previous post:
“One thing I DO notice while driving it is the takeoff from a stoplight. It wants to slightly hesitate, almost like it will stall- but only a blip, if that makes sense.”
I'll test my 05 TSX that has a similar engine to get normal map readings.
What kind of scanner do you have? Can you change the units on the MAF to g/s? The lb/s units make the output very low to see what it is reading. grams per second (g/s) give a larger number to see what the MAF is sending to the PCM.
For the O2 sensors, are you able to plot them over time? Hopefully you can get an equivalence ratio for O2 S1 1 or some conversion out of milliamps.
Below is a good video on P0420. The difference is your car has a wide-band O2 sensor as sensor 1 that works differently than old-school O2 sensors. His youtube channel has some very detailed videos on using scanners for O2 sensors that you may want to watch.
Your secondary O2 sensor is reading low and should read high values. This may be due to O2 sensor 1 reading lean values, so don't condemn the catalytic converter yet.
I have the Autel ML629. I think I should be able to change the unit type to g/s. I have been wanting also to check for any updates to its software.
Also, I DID see an “equivalence ratio” measurement in the live data. I can grab that next.
I will definitely watch the video, I need all the help I can get with the electronics end of engine management.
Last edited by coupdeaccord; Oct 18, 2023 at 07:59 AM.
I ran bluedriver on my TSX last night and put the results below. Unfortunately, MAF is not an option for my scanner.
Was any work done on the car before you originally replace the converter?
There are some differences between your numbers and mine. Your fuel trims are showing a severe lean condition.
The biggest difference is the MAP. My MAP is showing more vacuum at idle than your readings. Low intake vacuum could be caused by a number of items like timing, low engine compression, restricted exhaust/intake, faulty reference voltage. You'll have to start narrowing down potential root causes. Start simple and check your air filter to see if is severely clogged. Do you have the old catalytic converter? I'd also spray down the new exhaust manifold/catalytic converter area with soapy water to see if you have an exhaust leak. I'm not sure this would cause the map reading lower vacuum.
Your coolant temp is high enough where you cooling fans should be running, but I don't think this would cause your lean/P0420 problems. When the engine is cold, remove the radiator cap and top off the radiator. Inspect the radiator fins for damage or debris blocking air flow. With the engine running, turn on the a/c and make sure both fans are running. It is good to check your cooling system.
My O2S1 1 on equivalence ratio jumped between 0.975 and 1.025, so the value was oscillating. Plot both O2 sensors in a chart to see how each behave. The O2S2 1 should be flat lined and not oscillating.
I ran bluedriver on my TSX last night and put the results below. Unfortunately, MAF is not an option for my scanner.
Was any work done on the car before you originally replace the converter?
There are some differences between your numbers and mine. Your fuel trims are showing a severe lean condition.
The biggest difference is the MAP. My MAP is showing more vacuum at idle than your readings. Low intake vacuum could be caused by a number of items like timing, low engine compression, restricted exhaust/intake, faulty reference voltage. You'll have to start narrowing down potential root causes. Start simple and check your air filter to see if is severely clogged. Do you have the old catalytic converter? I'd also spray down the new exhaust manifold/catalytic converter area with soapy water to see if you have an exhaust leak. I'm not sure this would cause the map reading lower vacuum.
Your coolant temp is high enough where you cooling fans should be running, but I don't think this would cause your lean/P0420 problems. When the engine is cold, remove the radiator cap and top off the radiator. Inspect the radiator fins for damage or debris blocking air flow. With the engine running, turn on the a/c and make sure both fans are running. It is good to check your cooling system.
My O2S1 1 on equivalence ratio jumped between 0.975 and 1.025, so the value was oscillating. Plot both O2 sensors in a chart to see how each behave. The O2S2 1 should be flat lined and not oscillating.
IAT was similar to yours, so not an issue.
I do still have the original cat. The downstream O2 was stripped out and stuck, so I got a new one to replace it.
No other related work was done. There doesn’t appear to be any exhaust leaks.. no strange noises, smells.
I’ll check the cooling system well, but the AC doesn’t work lol.
I’ll check the air filter and plastic intake tube. What does the “faulty reference voltage” indicate?
I’m about to put a new O2 S1 in the car as well. Could the old one be wreaking havoc here?
Sensors like the MAP and MAF get a 5v voltage from the PCM. If that voltage is not 5V for some reason, the PCM will read incorrect values for the sensors.
What brand of sensors did you use for the secondary O2 sensor or the primary? I only use Denso aftermarket sensors or OEM Honda sensors. I believe Denso makes the OEM sensor. I get the sensor with the proper connector and not the kind you splice in.
You'll need to plot the primary O2 sensor equivalence ratio to see if it is oscillating between around 0.990 and 1.010. Either O2 sensor can cause this problem, but you want to do some testing before replacing a sensor.
Hey, how’s it going? Been a few. So this car is a nightmare, which I’m surprised for a Honda. New cat, both O2 sensors, MAF & MAP. Still getting an immediate CEL p0141 right after I clear it.
