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2001 VDC/SC One of a Kind
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I just downloaded the two files. Renamed them by removing just the .txt at the end. That leaves the .csv at the end, and they convert to spreadsheets that seem to display as expected.
Not working for me. When I download it, no matter how I do it, there is no ".txt" at the end of the file name to delete. It only shows the ".csv" and saves it as a txt document.
 

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2005 Legacy Wagon Limited 4EAT
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I added the .txt extension because the site wouldn't allow me to attach a .csv file. No worries. Here's the google drive links:
Highway:
Idle:

Short term fuel trim values are in there. ECT isn't. I didn't think to add that one.

I wasn't able to log knock correction because I'm using OBDWiz for logging and for some reason that parameter isn't in there. I'm not using Romraider because it doesn't have parameters for the 3 rear o2 sensors. It only shows one "rear o2 sensor". What's curious is at row # 1429 you can see when B2S2 goes lean, and it happens instantly. It goes from .7v to .1 in about 50ms. Even if it was a bad cat I would think a switch from rich to lean would happen more gradually no?
 

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Not working for me. When I download it, no matter how I do it, there is no ".txt" at the end of the file name to delete. It only shows the ".csv" and saves it as a txt document.
That's strange. Using Windows?

I just left-clicked on the first of the two files in the earlier post. That led to it being downloaded to my desktop. Here's what it looks like:

download first.jpg

A single click on the icon expands the file name:


downloaded file, to desktop.jpg

Then I right-clicked on it, selected "Rename", deleted just the .txt and then "Enter" to save it. A Windows pop-up asks if I really want to change the name, and I confirm. The desktop file icon changes from the text type to the standard spreadsheet form:

downloaded file, to desktop after rename.jpg

And this opens in Excel, as expected.
 

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I'm not using Romraider because it doesn't have parameters for the 3 rear o2 sensors. It only shows one "rear o2 sensor".
Wish I knew what car this is about (hint -- fill in the information in your Account Details under your avatar, so it shows up in each post).

If the car has "3 rear o2 sensors" and two pre-cat sensors (5 in all), Romraider will normally display them all. However, terminology becomes the factor. The pre-cat sensors are identified as "A/F Sensor #" where the # corresponds to the "bank", so A/F Sensor #1 is the pre-cat sensor on Bank 1 (RHS).

The sensors immediately after the two main cat converters are "Front O2 Sensor #" and the rearmost sensor at the outlet of the third converter is the "Rear O2 Sensor".

I wasn't able to log knock correction because I'm using OBDWiz for logging and for some reason that parameter isn't in there.
Because it uses the OBD data stream from the ECU whereas Romraider accesses Subaru's proprietary ssm data stream. The OBD data is basically that which the car maker is required to make available to anyone, e.g., non-Subaru service shops and personnel. The ssm stream is more comprehensive. Moreover, depending on the year, engine etc, there might be enhanced parameters that the Romraider developers have added, based on individual "definitions" of the particular ECUs.
 

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2001 VDC/SC One of a Kind
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@anarchyx34

I think your rearmost O2 sensor has a bad heater in it or it's worn out. That would be sensor 1/3 that is after the last cat. That is the one that leans out. The front cats look like they're working and change with fuel trims.

You have the P0420 because that cat is considered bank 1 even though it is at the rear of the Y-pipe. Unfortunately, if that cat turns out to be bad, unless you know of a shop that will weld one in, you'd have to replace the left pipe assembly. But right now, I think it's the sensor.
 

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2005 Legacy Wagon Limited 4EAT
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Wish I knew what car this is about (hint -- fill in the information in your Account Details under your avatar, so it shows up in each post).

If the car has "3 rear o2 sensors" and two pre-cat sensors (5 in all), Romraider will normally display them all. However, terminology becomes the factor. The pre-cat sensors are identified as "A/F Sensor #" where the # corresponds to the "bank", so A/F Sensor #1 is the pre-cat sensor on Bank 1 (RHS).

The sensors immediately after the two main cat converters are "Front O2 Sensor #" and the rearmost sensor at the outlet of the third converter is the "Rear O2 Sensor".
:geek: Yeah that was it. I see them now. New logs pasted below.


@anarchyx34

I think your rearmost O2 sensor has a bad heater in it or it's worn out. That would be sensor 1/3 that is after the last cat. That is the one that leans out. The front cats look like they're working and change with fuel trims.

You have the P0420 because that cat is considered bank 1 even though it is at the rear of the Y-pipe. Unfortunately, if that cat turns out to be bad, unless you know of a shop that will weld one in, you'd have to replace the left pipe assembly. But right now, I think it's the sensor.
Thanks for replying Cardoc.

I took two more logs today with Romraider this time. Mind taking a look?

This one I ran into some traffic unfortunately so it wasn't as steady as I'd like.


This one was going up a grade where I often see the CEL come on.
 

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The knock correction to 6.5 is not a good thing. What octane fuel are you using? Have you run a cleaner through the fuel or intake?
87 Octane. I haven't run any cleaners and have only cleaned the throttle body. I've only owned the car for about 2 months. I bought it with a bad engine (timing belt tensioner failure) and swapped in a used engine. The backstory for this car is..umm.. complicated. I made a separate thread about it:

 

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87 Octane. I haven't run any cleaners and have only cleaned the throttle body. I've only owned the car for about 2 months. I bought it with a bad engine (timing belt tensioner failure) and swapped in a used engine. The backstory for this car is..umm.. complicated. I made a separate thread about it:

So, with the knock up high at times as seen in your hill run, I am inclined to believe that the engine is carboned up. Did you take the replacement engine apart? As in removed the heads? With a cracked PCV hose for who knows how long, or with unknown gas running in it, carbon build up is high on the list. I would suggest you first try running a cleaner in the gas tank as well as a cleaner through the intake to burn the carbon out.

Did you install a new timing kit on the 2.5?
 

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So, with the knock up high at times as seen in your hill run, I am inclined to believe that the engine is carboned up. Did you take the replacement engine apart? As in removed the heads? With a cracked PCV hose for who knows how long, or with unknown gas running in it, carbon build up is high on the list. I would suggest you first try running a cleaner in the gas tank as well as a cleaner through the intake to burn the carbon out.

Did you install a new timing kit on the 2.5?
Yeah I had the heads off. Everything was fairly clean actually. There was literally no carbon in the intake ports as well.


The EJ20 that came out did have a lot of carbon buildup on the pistons however.

I'll try running some cleaners though it and see what happens. No harm in trying. I may also fill up next time with 93 octane to see what affect it has.

Oh and yes it has all new timing components. Mitsuboshi belt and all.

Plugs and wires are also brand new.
 

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The knock correction to 6.5 is not a good thing.
87 Octane. I haven't run any cleaners and have only cleaned the throttle body.
Knock Correction Advance (KCA) can be positive or negative. In my view, it doesn't necessarily indicate knock activity. That's because KCA is a derived (calculated) parameter based on several knock-related functions, some of which (e.g., Timing Advance Maximum) can be "good" adjustments.

To get a better idea of what's happening at any particular time I believe you would have to log Feedback Knock Correction, which is the short-term negative adjustment to timing advance (reduces timing advance) that is being applied at the time knock is being detected.

There's an explanation of the knock control strategy, and what KCA is based on, in the first post of http://www.romraider.com/forum/topic1840.html
 

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@cardoc

In both logs, the Front O2 Sensor voltages are oscillating, sometimes quite widely. These are fairly short logs, with fairly steady throttle, so the variations aren't explained by throttle changes. I wonder if this is showing cats that are borderline.
 

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@cardoc

In both logs, the Front O2 Sensor voltages are oscillating, sometimes quite widely. These are fairly short logs, with fairly steady throttle, so the variations aren't explained by throttle changes. I wonder if this is showing cats that are borderline.
I’ll try and take some longer logs when I get back from vacation in a few weeks.
 

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I had this PO420 code come up on three separate cars over the years, all higher mileage cars, but the PO 420 code never was a real issue. Drove two of the cars over 80,000 more miles after that code and when I got rid of the cars the code was not the reason....so perhaps it is the cat converter for some cars, but not all.
 

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2005 Impreza Outback Sport 2.5L, na, MT5, "Sue Bee"
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Hi @cardoc. Great info from you on this thread. I have my first Subie (05 Impreza Outback Sport 2.5-L naturally aspirated MT5) and I’m learning a lot from it.
Its history is unknown except it passed Vermont inspection a year ago. I’m now in NJ and emissions testing is the big thing here. I drove this car from Burlington VT to central NJ without it throwing a code. Does not overheat. On the way back from Burlington it ran like a champ. Gassed it up several times. Then I put injector cleaner in the tank with regular unleaded gas. Soon after it started throwing the P0420. I’ve done a lot of roadworthiness-related work to it like all 4 brakes and tires — also completed the 105,000-mi maintenance (it has 107.7k mi on it).
No other codes at all on the OBDII Reader. There is a problem with the interior fuel door release latch being rusted in place so the actual fuel door doesn’t close fully (I haven’t gotten around to fixing that). The fuel cap itself seems fine and I’ve adjusted it a couple of times — it seems to seal well but I really can’t tell.
I suspect the injector cleaner may be a culprit: perhaps it has dislodged crud in the injectors or in the engine, or by itself triggered the 0420 code. The 0420 is persistent and reappears (after being cleared) at about 60 miles. I’ve not driven the car enough to completely empty the tank yet and am about to put in another half tank of premium at Shell.
I just replaced the air filter, and the spark plugs/boots/wires, and they looked fine. Plugs were not burnt, nor over-gapped nor wet. At this point should I look at refilling the fuel, replacing the fuel cap and/or fuel filter as possible culprits to stop the 0420? I have about a month before I must get the car inspected and pass inspection.
 

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What brand of injector cleaner did you use? If you look through this thread or search on 'Seafoam', you will see several times where Cardoc has recommended it. It can be added to the gas tank (one can per tank full) and/or drip fed into the intake manifold using one of the vacuum fittings. I had the P0420 coming up persistently (even after new plugs, wires and new fuel injectors, etc.). I was beginning to think it was finally time to replace the cat but tried the Seafoam in the tank and the light has stayed off for around 1,000 miles now. If you have a laptop computer you can also do some in-depth diagnosis using the free Romraider software. You can log all of the engine sensors while driving and then open the saved file in Excel and plot various parameters (many examples in this thread) that can take much of the guesswork out of diagnosing this code.
 
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