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2007 Outback 2.5L 4AT Limited
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(1) I improved my smoke machine, hooked it up, and saw smoke coming out of the front air intake (see photo). Thinking this could mean the PCV valve was stuck open, I installed a new PCV valve (the check valve in the old one did move back and forth, but with some exertion I could blow a slight amount of air through it even when it was closed).
With the new PCV valve installed, smoke still came out of the front air intake. I disconnected the valve cover vent hoses and saw that the smoke is coming from the air box, and not the hoses (i.e., the smoke does not seem to be coming from the crankcase-see photo). Is this normal? If not, what does it mean?
(2) I've noticed the cycling/fluctuating TPS before. It's not my foot on the peddle, and I don't think it's the AC. I couldn't get it to happen today, but I didn't test it until after I'd changed the PCV valve--could that have made a difference? I'll see if it comes back as time goes on.
(3) In response to PlainOM's question about whether my scanner has A/F Correction #3, I'm not sure. There are PIDs titled STFT Bank 3 and LTFT Bank 3. Are either of these the same as A/F Correction #3? If not, I've provided screenshots of all the available PIDs. If any would be helpful to add, please let me know--I'll do so, and then post another log.
Many thanks to you both!
1.jpeg 2.jpeg IMG_3109 2.jpeg IMG_3110 2.jpeg IMG_3111 2.jpeg IMG_3112 2.jpeg IMG_3113 2.jpeg
 

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2001 VDC/SC One of a Kind
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Discussion Starter #2,322
When you introduce any smoke with pressure above atmosphere it is going to get by the throttle plate. It's normal. The thing to do is keep everything hooked up as normal but disconnect the intake hose after the MAF and seal it off. Keep the PCV hoses connected. This way the smoke remains in the intake, tubing and crankcase until it finds a way out. If it comes out of the exhaust you have a valve problem or partially open EGR because the valves in the heads, no matter where #1 is in the rotation, there will be no time when intake and exhaust valves are open at the same time.

Since you had the intake tube connected and not sealed. And the PCV hose was disconnected, you allowed for an easy outlet.
 

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Yes, 1 and 2 are to be expected.

. . . whether my scanner has A/F Correction #3, I'm not sure. There are PIDs titled STFT Bank 3 and LTFT Bank 3. Are either of these the same as A/F Correction #3? . . .
On my 07, which also has only two sensors, there's fuel "Corrections" and "Learning" PIDs with #1 and #3; none with #2. This is consistent with the FSM table of PIDs. Consequently, I suspect that your STFT #3 and LTFT #3 are the fuel trims based on the rear O2 sensor (the #1s are based on the front A/F Sensor). Guess we'll know with the log.
 

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Much appreciated. I'll add those two PIDs and post logs of the same test drive route. It looks like I need to re-epoxy one part of the smoke machine, so re-doing that test might take a few days. Thank you again.
 

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I added the STFT bank 3 and LTFT bank 3 PIDs.
Here is a link to the highway drive: July 6, Highway
Here is a link to the highway followed by street drive: July 6, Highway then street
I'm working on redoing the smoke test and purchasing a new front cat. I was thinking of purchasing an OEM unit from a dealership, but if you have advice on this purchase, or other parts that should go along with it, I'd appreciate it.
Thank you!
 

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Thank you. I'm thinking those new PIDs don't work--if I'm reading it right, they're all zeros.
 

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I added the STFT bank 3 and LTFT bank 3 PIDs.
Turns out I had that wrong. Neither is showing any activity. The Short Term Fuel Trim Bank 1 Sensor 2 is probably the one corresponding to the rear O2 sensor. (Confusing because different scanners use different names for individual PIDs, that don't necessarily agree with the names used by Subaru.)
 

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@cardoc
The price for that cat is amazing. (Too good to be true?) I saw your posts that they fit well. Any other thoughts about them? Are they designed so all the shielding can be bolted back on? I'm assuming yes, but with that price, I thought I'd ask. Thanks again for the link.
@plain OM
I get it--thank you. I will add STFT Bank 1 Sensor 2 and see what happens.
 

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I have put them on a few cars and they mount in like OEM. No finagling needed. Slides right up and lines up with the intermediate pipe.

I never tried to install the heat shields on them. Usually about the time the cat goes south the heat shields are rusted in too many places to bother. The absence of shielding doesn't effect the cat function.
 

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Just to add to the plethora of possibilities for a P0420 code to pop up, I had an 01 Outback H4 today that had the code. Right out the gate, bad ground cable from the battery to the bracket at the starter bolt. Subaru didn't have a cable set available today so I went another route with a 4 gauge cable, 3' long, with an eyelet on one end, clamp on the other and made a 4 gauge cable and spliced it in for the ground from the post to fender. Cleaned up the other grounds and problem solved.

Cat is good. Engine is running great.

Car has 168k miles.
 

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I'm about to take my 08 MT Outback for its 250,000km service - cam belt, etc. I was asked about any issues to investigate and I explained about the P0420 only happening at highway speeds and the tech immediately said "that's in lean cruise mode". I've searched this site for "lean cruise" and nothing. Searching more broadly, i.e. google, and "lean cruise" is a fuel map only used in Australia, and was chosen to improve highway fuel economy at the expense of possibly higher NOx emissions. This is a subaru specialist service centre, so I'm hoping they have some experience with this. I'll find out tomorrow!
 

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@dwywit The car runs lean with light throttle application, about 16-18:1 AFR, but it's not sustained there for long periods since combustion and engine temps will rise. When the car runs lean fueling it doesn't effect a P0420 because the ECM knows the rear O2 will also lean out. The ECM sets a P0420 when there's a waveform from the rear O2 that matches, or closely matches the STFT waveform in sustained throttle application regardless of city or highway driving.

Your "tech" is misinformed concerning the P0420. I'm not saying he's wrong about a lean map, just the results.
 

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@cardoc @plain OM
I wanted to say thanks again for all the help before. I finally got around to changing the CAT after your diagnosis sometime last week or the week before that. The CEL went off on its own but there was one still stored in the computer. I used my scanner after 3 days to remove that code and it hasn't returned.
I didn't bother with trying a warranty and I'm still not 100% convinced the cat I put in from eastern was bad. The bolts that hold it to the front section of pipe came off pretty easy but the gasket wasn't black. I'm beginning to wonder if there was actually an exhaust leak prior to the AF sensor this whole time. Just can't be sure so the new one went in and all seems good now.
 

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@dwywit The car runs lean with light throttle application, about 16-18:1 AFR, but it's not sustained there for long periods since combustion and engine temps will rise. When the car runs lean fueling it doesn't effect a P0420 because the ECM knows the rear O2 will also lean out. The ECM sets a P0420 when there's a waveform from the rear O2 that matches, or closely matches the STFT waveform in sustained throttle application regardless of city or highway driving.

Your "tech" is misinformed concerning the P0420. I'm not saying he's wrong about a lean map, just the results.
Thanks - he didn't actually say the P0420 was caused by the lean cruise mode, only that lean cruise will happen after a sustained period above ~90km/h, and that's the only time I get a P0420. I've just got the car back, they said they couldn't find an actual fault in the emissions system, but the air filter was quite dirty. He suggested that I try the spacer trick on the rear sensor - he would have done it but didn't have any in stock.

Driving home on the highway, no P0420 until about 30 minutes at 110km/h. I was getting quite excited - usually the fault will appear after about 5-10 minutes. Oh well, off to ebay for a spacer. Any recommendations?
 

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@dwywit
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Record engine data and post it so we can see what the engine is doing. Since you want to put a spacer in you'll not be doing any more damage by logging data to find the problem. The tech missed the problem maybe because he doesn't know yet what to look for, or, he didn't get the car to operate in the same way that sets the code. Since it comes on while you're driving, your foot input is a factor.
 

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@dwywit
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Record engine data and post it so we can see what the engine is doing. Since you want to put a spacer in you'll not be doing any more damage by logging data to find the problem. The tech missed the problem maybe because he doesn't know yet what to look for, or, he didn't get the car to operate in the same way that sets the code. Since it comes on while you're driving, your foot input is a factor.
Thanks - I've got the BFAX dongle and TorquePro. I'll set it up to log some data. It'll be next week before I hit the highway again.
 

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Following up on post nos. 2321 and 2326, I sealed the intake after the MAF and re-did the smoke test. The only place I saw smoke come out was the EGR valve (see photo). I saw no smoke at the tailpipes. From other posts, it seems this may be normal. [Question 1] Does that seem right, or should I replace the EGR valve gasket? (And the EGR valve itself?)

I also replaced the front cat. I went with a Walker, p/n 16564. The fit was fine. I reinstalled the middle sections of exhaust shielding, but the other sections had a totally different contour and couldn't go back on. Here's a log showing a post-cat replacement highway drive: Aug. 2, 2020 Highway. [Question 2] Does this log look normal? Does it look like the new cat is working? Are there any other PIDs that would be helpful for analysis?

I've only driven the car a few times since I replaced the cat. My scan tool still shows the P0420 code, but now it also shows P0108 (MAP high input). I don't know when this code popped up, but around 2 months ago I removed the MAP sensor and sprayed it and its bore with carb cleaner (see post no. 2196). [Question 3] Does this mean I should replace the MAP sensor?

[Qustion 4] Should I reset the MIL using my scan tool, or is it better to wait and see if it goes out on its own after more driving?

I never conclusively figured out why the stock cat failed. The car has ~115k miles. So far, I have changed the plugs and air filter and checked for exhaust and vacuum leaks. If there are other steps I should take, I'd appreciate the info.

Thank you once again!
IMG_3273 2.jpeg
 

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Hi,

I have an intermittent P0420 I thought I would share to get some ideas on what might be the problem.

Vehicle is a 2005 Outback 2.5L (Australian). Odometer is on 160,000km. No other fault codes or problems I am aware of. It had a P0420 about 6 months ago which was cleared during the regular service (the tech didn't investigate it). The fault code came back last week. So, that is two times I've got the P0420 so far.

I have used a scan tool to record some data. The scan tool is an Autel AL519. It doesn't state the timestep for each recorded 'frame', but it seems like about 30 seconds. The data is in the table. This was recorded while stationary, in neutral, and pushing the throttle to get about 1500 rpm or 2000 rpm. Ambient was about 20 degC.

I'm new to this, but from what I have read in this thread (thanks Cardoc) and others, the O2 sensor values seem about right (2.7V for the upstream sensor and between 0 and 1V for the downstream sensor). I can graph live data on the tool (can't download it sadly), and the downstream sensor seems to oscillate between 0 and 1V quite quickly, and the upstream sensor moves around 2.7V more slowly.

Does anything look like a problem to more experienced eyes than mine? I don't want to keep clearing the code if there is some underlying problem that should be fixed.

Thanks!

enComplete Data Set
Number of DTCs stored in this ECU 0
Fuel system 1 statusCL
Frame Number
1​
2​
3​
4​
5​
6​
7​
8​
Calculated Load Value(%)
2.7​
4.7​
5.1​
5.1​
5.1​
3.9​
4.3​
4.3​
Engine Coolant Temperature(degC)
91​
92​
94​
95​
97​
97​
96​
95​
Short Term Fuel Trim -Bank 1(%)
-0.8​
0​
-3.1​
7.8​
3.1​
0​
0​
0​
Long Term Fuel Trim - Bank 1(%)
-1.6​
-1.6​
-1.6​
-1.6​
-1.6​
0​
-1.6​
-1.6​
Intake Manifold Absolute Pressure(kPa)
32​
23​
24​
24​
25​
26​
23​
23​
Engine RPM(rpm)
1449​
1702​
1893​
1928​
1932​
1480​
1602​
1587​
Vehicle Speed Sensor(km/h)
0​
0​
0​
0​
0​
0​
0​
0​
Ignition Timing Advance for #1 Cylinder(deg)
24.5​
24.5​
28​
28.5​
27.5​
25.5​
22​
22.5​
Intake Air Temperature(degC)
59​
59​
60​
60​
60​
61​
61​
61​
Air Flow Rate from Mass Air Flow Sensor(g/s)
5.25​
5.84​
5.9​
6.04​
5.9​
5.05​
5.12​
4.99​
Absolute Throttle Position(%)
17.6​
17.3​
17.3​
17.3​
17.6​
16.9​
16.9​
16.5​
Location of Oxygen SensorsB1S12--B2S----
0​
0​
0​
0​
0​
0​
0​
0​
Oxygen Sensor Output Voltage Bank 1-Sensor 2(V)
0.555​
0.145​
0.11​
0.84​
0.44​
0.065​
0.075​
0.125​
Short Term Fuel Trim Bank 1-Sensor 2(%)
0.8​
-0.8​
-0.8​
0.8​
0​
0​
0​
0​
OBD requirements to which vehicle is designedEOBD
0​
0​
0​
0​
0​
0​
0​
0​
Distance Travelled While MIL is Activated(Km)
0​
0​
0​
0​
0​
0​
0​
0​
Equivalence Ratio (lambda)(Bank 1-Sensor 1)
0.945​
0.976​
0.987​
0.997​
0.994​
1.012​
1.002​
0.986​
Oxygen Sensor Voltage (Bank 1-Sensor 1)(V)
2.419​
2.648​
2.721​
2.785​
2.76​
2.858​
2.809​
2.711​
Equivalence Ratio (lambda)(Bank 1-Sensor 1)
0.945​
0.976​
0.987​
0.997​
0.994​
1.012​
1.002​
0.986​
Oxygen Sensor Current(Bank 1-Sensor 1)(mA)
-0.234​
-0.094​
-0.059​
-0.016​
-0.02​
0.031​
0.008​
-0.051​
 
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