02 Subaru Forester Catalytic Converter Issues?

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#1
MAKE: Subaru
MODEL: Forester
YEAR: 2002
MILES: 160,000
ENGINE: 4-cyl 2.2

Trouble Code: P0420

Losing approximately 1 quart of oil/month (every 2k miles)
No driveway stains - confident we're not leaking much if any

Some dark exhaust staining on the tailpipe exit

KICKER: When I drive the car up to about 3,000 feet elevation, the trouble code goes away and the car maybe even seems less sluggish (could be my imagination on the performance)

I don't know where to go with this other than a CC problem. Any ideas?

MikeD
 
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#2
sure its a 2.2L? maybe a 2.5L?

ANYWAY that's a lot of oil consumption.....you might look at that- 2002 I think is before the problematic ring issue.
ideas
If applicable the turbo when the seals go they consume big time- How do plugs look? do not use a K&N type filter. Use correct T'stat. Check PVC.
you would want to use scanner and check FT's, MAP and ECT - ALSO LOOK AT THE ACTUAL O2 VOLTAGES...
maybe do an exhaust system back pressure test- would look at that sluggish issue...
 
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#3
No turbo on this one.
Plugs are clean.
I'll put the scanner on it and report back.
Thanks!
MikeD
 

nickb2

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#4
Sadly, with a high oil consumption like this you may have clogged the cat. But, black smoke usually means the car is leaning out due to a possible exhaust leak and the ECM is enriching, hence the black smoke.

I see only a 2.5l non turbo. No 2.2l available for this car. Turbo for this model started in 2004 and still in 2.5l.

Are you having any idle issues or stalling?

Do you have any exhaust leaks?

Do you know how to do a back pressure test as Kev2 suggested to confirm cat blockage?

Are there any other code present?

When you clear code/s, is it only the P0420 that comes back?

I do not see any TSB's of note for this code on this model.

Check, as said before, for any leaks in exhaust system.

Do you know what fuel trims are? And if so, do you have a way to check them?

regards,

Nickb2
 

jd

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#5
Yep. 2.5 and non-turbo. There was a TSB about heads, head gaskets, if I remember. Repair was done by a dealer just before the time or miles ran out, around 80,000-Miles again if I remember. Just seems to me that things like the Valve Guide Seals should be "low mileage" at least thinking they were changed on the TSB repair.
Have any Sensors been replaced? Knock Sensor, O2 Sensor(s)? Others? I remember a misfire on one cylinder, burned coil terminal and associated cable terminal. Changed Coil and Ignition Cables. And Plugs... All looked alike and none oily.
What was the Ring Issue about?
 
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#6
check the PCV and hose for evidence of excess oil.
As for the ring issue -Try google "Subaru ring problem" that will get you some info and years affected.
for back pressure - there is a gauge that is swapped into an o2 sensor for testing OR a vacuum gauge can be used- maybe available as rentals or loaners at parts storws.
 

jd

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#7
Doesn't seem it's new enough for the ring problems described in the gOOgle search, Lawsuit, TSB's etc. The oil consumption's a relatively recent development with this 2002 Forester. Seems to me that the "boxer" style engine layout makes it easier for crankcase oil to get to the pistons. Anyhow, can it burn that much oil and not have it show on the plugs? I can see how the converter could burn the oil so completely that the exhaust didn't smoke, but the burning oil not show on the plugs???
 

billr

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#8
Yes, an engine can gobble oil and not have it show on the plugs or affect emissions. The S-series Saturns that I love so much are notorious for using lots of oil, but there are no problems from that unless you don't check the oil level regularly and run the engine without lube.. Subaru is not the only flat-opposed engine, don't blame high oil use on that. Ha, at one time there was even BS about pistons wearing rapidly with anything other than vertical cylinders!
 
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#9
Yes it is the 2.5L sorry for the typo.

I put the scanner on looking for the O2 sensor data etc. and could only get one sensor to report. I have Bluetooth OBDII with Torque lite. Anyone know if the full version of Torque will let me see data on all sensors or is this an issue with the car?
Also, a particularly strange phenomenon is that after I clear the code, the car usually stalls on the next startup, but at no other time.
I think I could perform the back pressure test but I don't have the vacuum gage. I'll see if the local parts place lends them out.
We have replaced O2 sensors at various points to get it to pass emissions but not the knock sensor.

Thanks all,
MikeD
 
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#10
stall after clearing code- I would not worry if it corrects on second start- erasing a code dumps the code and much data including - so called adaptive's, learned settings, monitors etc...
You mention 3000 feet that's rare - Colorado? You are not using that 83 octane -
do not give up on her without testing at least the fast inexpensive testing.
look at the PCV system....noticeable wet with oil in tubing?
Again I ask is it reaching temp what is ECT?
which sensor reported and what was voltage?
why are you now questioning KS knock sensor?

you need to talk with scanner manufacturer tech support - what each brand will do is always different- one question you should ask will this scanner read ALL codes the manufacturer specific?
 

nickb2

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#11
If you have the OBD2 bluetooth dongle, scrap that torque lite app, the torque pro is no really any better a thing for your I phone app.

Go for something like proscan or something similar. What is your OS? Windows version #???

Is your dongle a canadian based ELM device? It was originally a canadian based company but was soon copied by the chinese which swamped the market. So if buying those inferior elm's, highly suggest to buy a few. A 10-20$ a pop, not a huge loss if one does not work out of the box. Also, make sure you have the 5.5 proscan version and elm 1.4 dongle version. From what I gather, the 2.2 version is for the android app shyte and I have no use for that. I use strictly laptop or PC based.



You probably own a laptop, right?

Try this link for free software. Many of them work great with a proper setup. A phone is still just a phone and cannot have the processing power of a good laptop and high baud rates needed to see live data switching.

http://elmelectronics.com/obdsoftware.html

You need something that will read PID data. Torque lite and the pro versions are still just glorified code readers and a app gadget to see what fuel mileage you are getting and some fake dyno results etc. Don't get me wrong, for a free app, it can help. But not for in depth diagnostics.

I am not allowed to give cracked software links here, so check out on your own. They are readily available and will work with a good interface. Some of the software state they will only work in older versions of windows. They can be run in compatibility mode.

Linux is more stable across the board, but restricted in software abundance compared to windows OS's.
 
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nickb2

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#13
Especially check step # 2 of the above flow chart. I have seen a lot of guy's just say, ahh, it can't just be that!!

YES IT CAN!

That black smoke is TELLING you something!! That is why I asked for fuel trims, which a torque app will not give you.

Raw fuel is being dumped in there for a reason and the cat could be cooked already. Most likely already a done deal. The coating of the honeycombs could be already beyond its capability to perform. I check this out often when I get a dreaded P0420 code with a laser temp gauge.

How is acceleration and engine performance? Is it sluggish. If so, does it improve with the pre o2 sensors removed? It may sound like a nascar, but subbie's are loud off the lot anyway. That's why I don't like them. Those cars sound like a sick cow farting when they drive away. But they do make for fun driving. :p
 

jd

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#15
Hmm.... Fuel... Doesn't run all that badly, right? But poor gas mileage for a car that size, way lower than three other 2.5L Subies that've been in the family. Fuel trim isn't a term I understand, but... Raw gas washing oil off the cylinder walls and out the exhaust?