MAF problem

Hi guys, I need help on my car Toyota Avensis Verso 2002 2.0L engine European market.
I am having rich condition and I believe it’s destroying my CAT even though I already have it replaced and I’m getting P0420 and P0430.
I am suspecting my MAF sensor because when I look on the Toyota techstream data list, the MAF reads correct at idle base on factory service manual information, but when I step on the gas pedal without load and increase my RPM to 2500, my MAF sensor g/sec reading does not change at all until after 5 seconds or so then it jumps to 7.5g/sec but not progressively.
I saw some YouTube videos and just tapping on the gas pedal the MAF reading changes accordingly and progressively just like a TPS would do.
Is my MAF gutted or am I having a dirty MAF. After I bought this car I have cleaned the MAF like 3 times and that brought down my STFT from -21.09 to around 3, but I am still experiencing loss of power and hesitation when I try to move from dead stop.
My second question is when I did a health check using the techstream, I saw calibration ID but the last column after the calibration column which is suppose to be the “update” column is missing. I am attaching important screenshots for your kind help. No point going to any mechanic here again because I have been to like 4 mechanics even Toyota dealership where I bought brand new upstream A/F sensors hooked up their computer and said nothing wrong with my car when I know 100% for sure the car is faulty, at least from the drivers point of view I can tell a good running car with my 19years behind the wheels. No other DTC apart from the CAT DTC’s
Before I move further in diagnosis how do I update this car’s software and get it properly calibrated, so I can stop changing parts if the real problem is just a simple software update. Second pix is a sample from google, but on mine that last update column is missing. By the way my MAF is integrated with IAT (5 wires in all).
Also if this means anything my Evap VSV is off from my data list but Toyota service manual says it should be on, I’m so confused because other ones on YouTube are off.

Have you think that maybe your scanner is a bit slow on update data about the MAF ??


To be more sure about the P420 dtc you have to check stft and ltft at idle and at 3k rpm
keep in mind frond and rear O2 readings also, to see your cat condition fully warm

I was thinking in that direction also, but all other components respond rapidly using this techstream, only way to find out is to hook up a different WiFi OBD2 reader that I have which luckily for me also has MAF readings.

One of my mechanics during idling listened to the exhaust at the tail pipe and said it sounds like a bad muffler, I just don’t want to change any parts at this point without 100% certainty.
My downstream sensors readings show a bad CAT, even if I am going to change my CAT again I want to be 100% sure something else is not destroying it.
My question is which do I consider first priority in this diagnosis.
1. Dealing with the upstream sensors readings first or
2. Dealing with the downstream sensors readings.
From the pix attached you can see clearly the voltage drop in the graphs of my upstream sensors which I believe signifies a rich condition.
What could be the cause of my rich fuel mixture and low exhaust oxygen content.
Also there was a time I was driving and I had the techstream hooked up and at a time even when under load my MAF reading was static and not moving, and when I parked without load at 2500RPM it picked up again.
Can a bad CAT or clogged exhaust system affect MAF and fuel trims?

Yes, a clogged exhaust can and will affect maf readings and fuel trims. This because of restricted aspiration....

Check your intake pressure (engine vacuum) at idle with a vacuum gauge and then at 2500 rpm/no load. Make sure the reading does not drop after a couple of minutes.

I'm unfamiliar with the Tech stream tool, but if it was me, I would want to select only the MAF voltage data pid and graph it. This would help speed up the data rate like Scanner Danner teaches us. Slow data could cause sensor inputs to appear erratic on your scanner.
I would then ideally want to scope the MAF signal and compare that to what the scan tool shows.
If then the MAF is still not reacting to changes in throttle position, check the power and ground at the sensor.
If power and ground are good, and the sensor doesn't recognize changes in air flow, it would be time to change the sensor.

I would think that if the readings your scan tool is showing were correct, there would likey be a MAF performance code, or MAF & TPS correlation code, but that may not be the case.

I have tested the MAF sensor with a WiFi OBD2 and it responded swiftly as it should.
When I rev my engine at the car park to 6500RPM, my MAF and TPS don’t go past the figures below. See attached images also
MAF: 48.17grams/sec
TPS: 32.94%
IAT: 20.00 degrees Celsius
With Ignition on and engine off, if I floor my gas pedal my TPS reads 80%.
This techstream software does not have any graphing / pid for MAF

See attached pixs

I always look at OBD2 data before manufacturer mode it tends to be more trustworthy. You can actually check MAF output with a volt meter it is easy to pick ou the MAF signal wire from the 5 wires as it is the only voltage from the 5 wires that changes when you rev the engine.
It certainly sounds like the Cat might be melted so you need to check for blocked exhaust.
Be aware that a lot of the MAF sensors being sold as replacements for some models are either not of the right calibration for a particular engine or are of poor quality and only last a short length of time.

Since you talked about calibration of MAF, I think the first step in solving this problem is to update my car’s calibration ID. Because with improper calibration in the car engine ECU then I can’t really do much or move further in this diagnosis.
I am attaching an image of freeze frame data when the CAT DTC’s set, guys please kindly interpret this data for me, I am suspecting the intake air is weird and this may have been caused by my MAF giving wrong reading as a result of bad calibration. Note I have never changed my MAF sensor, it’s still the same factory MAF that came with the car, except one of the previous owners changed it that I’m not aware of.

I am not an expert and also I don’t have a scan tool with scope or graphing. The only graphs this techstream gives me are all the sensors, fuel trims.

You need to look at the pre-cat (upstream) sensor output not sure what type of upstream sensor if the 2002 European Avensis had buta snap throttle test that will tell you if the sensor is working also a propane test. Normally Toyota keep very tight control of the fueling. Also are you 100% sure it isn't just a failed downstream O2 sensor the only job of the downstream sensor is (on 99.9%) of engines to flag up a P0420 code.