Subaru Outback Forums banner

1761 - 1780 of 1819 Posts

·
Premium Member
Joined
·
11,878 Posts
Discussion Starter #1,761
@car doc
this is what the graph looks like
What you are looking for is a drop in correction value. Usually when you have a vacuum leak and you hit the spot where it allows the accelerant you are spraying to enter the intake the AF Correction will drop to a negative value since the accelerant makes the air flow rich in fuel. If the ECM is adding more than 10% during correction, then the trim may only drop to near 0 (zero).

Is the graph jumping around between 0 and 5% at idle? If so, that's normal. Even if it goes to a negative value, as long as it's not over 7-10%, it is normal. The way the fueling works is the ECM constantly switches rich to lean to control the catalytic converter temperature and operation. When an engine is running good and the management is all operational as intended, you will see fuel trim fluctuation at idle in a graph. The LTFT is the average correction made over time. This number will also change when the car is driven since under load the fuel map changes.

In old cars that used carburetors the fueling was constant based on the engine vacuum. With throttle body injection that came around with CARB requirements and catalytic converters, the fueling was still constant but the injector(s) made it easier to manage fuel volume and consistency based on an oxygen sensor feedback. The systems didn't switch back an forth to control the cat temps as much as to maintain a 14.5-14.9:1 ratio to manage hydrocarbons. Delphi came up with the system that is used now to manage the catalytic converter and help it last longer than the old styles. The old styles would overheat and melt causing blockage and they wouldn't last very long, where catalytic converters made in the last 20 years and managed under the present fueling system last for an unknown time frame when the engine performance is kept up to par.
 

·
Registered
Joined
·
31 Posts
@tmcquinn

I don't mind if you post up questions about a WRX, Forester, Impreza, what ever. It's all Subaru.

This thread also applies to other makes and models when it comes to diagnosing a P0420 and the root cause for the lack of efficiency on the cat's part so the info here can be used with other vehicles, even German cars.

There should only be piping between the cylinder heads and the turbo. If you have a CAT prior to the turbo, something isn't right. You don't want any restrictions prior to the turbo and a catalytic converter is a restriction. The exhaust manifolds feed to the turbo, then you have a CAT in the downpipe coming out of the turbo followed by another pipe with either a second cat and/or a resonator.

All you need is the downpipe cat. After that, you can put in whatever you like for sound, or no sound.

As far as what killed it, I'd say it was damaged by the engine failure or it started before the engine failed and it's digressed to it's current state. Rich fueling doesn't help any either.

When you get the CAT installed, clear/reset the ECM and drive it for a couple days so it will relearn the fuel trim, then you can log data from the car and post it up here in a zip folder.

Rom Raider is relatively easy to use. Once you choose the parameters to log, you can save the profile and every time you connect to the car it will automatically load that profile.

To Log:
AF Sensor (either voltage or Lambda/Stoich)
O2 Sensor (voltage - don't need the heater circuit or resistance)
ECT
TPS (Voltage and %)
MAF
MAP
Wastegate
STFT
LTFT
Fine Knock Correction
Ignition timing
Injector pulse
RPM
Battery Voltage (at least for the first few logs)

You may also want to think about getting it tuned proper, either for performance or economy. Plenty of tuners work via email. A few are on this forum.
So I have the new cat and the new A/F sensor installed and we have Romraider going. I'm ready to log and try to convince myself that the cat killing issue is no longer with me. The battery was disconnected while I worked on the car.
Do I start logging now or wait until the ECU gets out of 'learning mode'? (Not too familiar with learning mode...)
 

·
Registered
Joined
·
31 Posts
@tmcquinn

I don't mind if you post up questions about a WRX, Forester, Impreza, what ever. It's all Subaru.

This thread also applies to other makes and models when it comes to diagnosing a P0420 and the root cause for the lack of efficiency on the cat's part so the info here can be used with other vehicles, even German cars.

There should only be piping between the cylinder heads and the turbo. If you have a CAT prior to the turbo, something isn't right. You don't want any restrictions prior to the turbo and a catalytic converter is a restriction. The exhaust manifolds feed to the turbo, then you have a CAT in the downpipe coming out of the turbo followed by another pipe with either a second cat and/or a resonator.

All you need is the downpipe cat. After that, you can put in whatever you like for sound, or no sound.

As far as what killed it, I'd say it was damaged by the engine failure or it started before the engine failed and it's digressed to it's current state. Rich fueling doesn't help any either.

When you get the CAT installed, clear/reset the ECM and drive it for a couple days so it will relearn the fuel trim, then you can log data from the car and post it up here in a zip folder.

Rom Raider is relatively easy to use. Once you choose the parameters to log, you can save the profile and every time you connect to the car it will automatically load that profile.

To Log:
AF Sensor (either voltage or Lambda/Stoich)
O2 Sensor (voltage - don't need the heater circuit or resistance)
ECT
TPS (Voltage and %)
MAF
MAP
Wastegate
STFT
LTFT
Fine Knock Correction
Ignition timing
Injector pulse
RPM
Battery Voltage (at least for the first few logs)

You may also want to think about getting it tuned proper, either for performance or economy. Plenty of tuners work via email. A few are on this forum.
It took me a while but I'm back!

2003 WRX, 5 speed, stock

New cat, new A/F sensor(Denso), 2,400 miles on new MAF (Denso), 4,000 miles on rear O2(Denso). 17,000 miles since we built the engine.

I think I got most of the PIDs. I'm not too sure about the A/F Sensor, Wastegate, and Fine Knock Correction. I was guessing. I appreciate what you're doing and I'm more than willing to do this however many times it takes for me to get it right.

My steady 45mph file wasn't as steady as I wanted. There were some hills and a lot of traffic.

Since we were looking at the wastegate, I tried to open it up a bit on the 55-70mph file.

Something went wrong with my first attempt at logging the cold start. I let the engine cool until the turbocharger was no longer hot and captured a couple of minutes at idle after the other 2 logs.

Anything I can learn to lessen the odds of ruining the new cat will be worth however much work the logging and analysis takes. I have 4 Subarus and I really want to learn this. I fell asleep a couple of times reading this thread but I made it through the whole thing.

I've changed a few O2 sensors but the A/F sensor was a bear. I had help from a machine shop that specializes on bolt extraction and even the machinist had quite a time with it.
 

Attachments

·
Registered
Joined
·
611 Posts
Hi Cardoc,
I hope you had a good July 4th weekend. I'm still wrestling with the P0420. I pulled out the injectors and cleaned them as best I could with lacquer thinner. I have an extra set I'm sending out to get ultrasonically cleaned. I also checked the alternator output with AC on (cycling), head lights, brake lights on. It comes pretty close to the 13 volt limit. I did clean the the intake manifold grounds too. The test runs seem to show a little less knock correction but you can see that the rear O2 sensor is fluctuating a lot at idle and low load. I would much appreciate your opinion on where to go next. I also check fuel pressure and got 36 at idle with regulator and 46 with vacuum pulled off regulator. Also checked PCV valve which I had replaced not too long ago and it still rattles.
 

Attachments

·
Premium Member
Joined
·
11,878 Posts
Discussion Starter #1,766
@MikeC5
Here's what it looks like to me.
The ECM may be correcting fuel to manage the catalytic converter and in doing so the knock is active. With everything you've checked ad corrected I can't think of anything that would cause the knock unless you are running with low octane fuel. The catalytic converter is not going to work right so it needs to be replaced.

This one is Evan-Fisher and has a 5/50 warranty: https://www.ebay.com/itm/Evan-Fischer-Catalytic-Converter-Subaru-99-05-Forester-00-05-Outback-Legacy-/371257286213?vxp=mtr&hash=item5670a89e45

After you get a replacement, run a log warmed up so we can see what it's doing.
 

·
Registered
Joined
·
611 Posts
Thanks Cardoc. I am running 87 octane and I think I'll try a couple fill ups with hi-test and maybe another bottle of Seafoam before a new converter (unless you think it's too late). Does the alternator output concern you?
 

·
Premium Member
Joined
·
11,878 Posts
Discussion Starter #1,768
@tmcquinn

The knock correction is an issue. I'm not convinced the cat is bad yet and I don't think there is any restriction. The rear O2 sensor is responding to the throttle changes and fuel/air.

Some things that need to be checked/corrected:
One is I hope you are using high octane fuel.
Restriction in the fueling supply.
PCV system.
Combustion chamber cleaning to make sure there's no carbon build up. (Sea Foam or B12 drip while idling at 1500 rpm)
Did you say this car was tuned or it's not?

I would also like to see the wastegate and IAT sensor added to the logs.
203°F is kinda high. Is the coolant full, fans working, was the AC on, is it still really hot up there, anything restricting air flow through the radiator?

Gotta find the knock source. When it's not knocking the cat and fuel trims are decent. According to the AF sensor, the fueling is rich while it's knocking so I'm inclined to think carbon build up.
 

·
Registered
Joined
·
31 Posts
@tmcquinn

The knock correction is an issue. I'm not convinced the cat is bad yet and I don't think there is any restriction. The rear O2 sensor is responding to the throttle changes and fuel/air.

Some things that need to be checked/corrected:
One is I hope you are using high octane fuel.
Restriction in the fueling supply.
PCV system.
Combustion chamber cleaning to make sure there's no carbon build up. (Sea Foam or B12 drip while idling at 1500 rpm)
Did you say this car was tuned or it's not?

I would also like to see the wastegate and IAT sensor added to the logs.
203°F is kinda high. Is the coolant full, fans working, was the AC on, is it still really hot up there, anything restricting air flow through the radiator?

Gotta find the knock source. When it's not knocking the cat and fuel trims are decent. According to the AF sensor, the fueling is rich while it's knocking so I'm inclined to think carbon build up.
Wow, worse than I thought...

It's 93 octane Shell.

I will try another PCV valve. This one has about 15,000 miles on it.

So I guess those are the wrong wastegate parameters. I'll have another go at it. The IAT should be no problem, if memory serves.

The coolant was full and both fans work but it was really hot. Nothing is restricting the radiator. I probably did have the A/C on.

I'll read up on Sea Foam and knocking and I will be back.

No tune, 100% stock except for things like ARP studs and a Killer Bee oil pickup. The original engine had a tune but I unmarried the Cobb A/P from it and restored the factory settings before we ever started the new engine.

I'm in the middle of changing both rear wheel bearings in the 2002 so I'm underwater until that finishes. I see why a garage charges so much to do it now.

Thanks a million for your help.
 

·
Registered
Joined
·
31 Posts
Keep it on this thread. That way people can see what is transpiring to conclude the issue.
Ok, the other car is back on the road so I'm chasing the knock (car has been parked until this is solved).

I have purchased a new fuel filter, PCV valve, 4 NGK iridium plugs, and a can of B-12 Chemtool. I'll have a look into the cylinders with my inspection camera once the plugs are out.

Is my goal here to have all zeroes in the 'Knock Correction Advance degrees' column?
 

·
Registered
Joined
·
31 Posts
@cardoc

I am wondering now if I had the correct PID for knock. I read this thread - http://bit.ly/2YU3k33 - and I'm thinking that 'Fine Learning Knock Correction (degrees)' is what you wanted.

I added the PID to the right and put it into a Google Sheet to make it easy to view - Google Sheet I just used the Google Sheet to make it easy to see what I meant. If I'm right about the PID I will concentrate on finding the correct wastgate PID, log again, and upload another .zip file. Something is stopping me from uploading .zip files right now but I will figure something out.

Anyway, that PID is way lower. Maybe I don't have a problem with the engine, just my ignorance? (The new parts won't be wasted. My other son has an 02 that can use them.)
 

·
Premium Member
Joined
·
11,878 Posts
Discussion Starter #1,774
That Google Sheet works. They've changed something and now you can't upload zip folders and still can't upload csv files, so I'm gonna have to look in to it and we may have to change some stuff up so we can see people's logs.
The car looks to be running good. This is after the plugs were changed?
 

·
Registered
Joined
·
31 Posts
That Google Sheet works. They've changed something and now you can't upload zip folders and still can't upload csv files, so I'm gonna have to look in to it and we may have to change some stuff up so we can see people's logs.
The car looks to be running good. This is after the plugs were changed?
No, sir. I didn't change anything on the car yet. I just added what I was hoping is the correct PID for knock. That engine only has 17,000 miles on the plugs, PCV, and fuel filter. I have a 2002 that could use those parts if this car doesn't need them.

Now let me see if I can find the proper wastegate parameter that you requested and I'll do a proper log.

Thanks!
 

·
Registered
Joined
·
31 Posts
Yay!

So would you like to see new logs for cold start, 45 mph, and 55-70 logs again with the proper knock PID, or do you think I'm good to go?

I think that Romraider is going to be a great diagnostic tool going forward. I resisted it for far too long.
 

·
Premium Member
Joined
·
11,878 Posts
Discussion Starter #1,778
Yay!

So would you like to see new logs for cold start, 45 mph, and 55-70 logs again with the proper knock PID, or do you think I'm good to go?

I think that Romraider is going to be a great diagnostic tool going forward. I resisted it for far too long.
What you posted has the right PIDs. It all looks good. You may still want to consider getting it tuned so it will run better. There's quite a few tuners that work through e-mail transfers and you would use ECUFlash to rewrite the ROM.
 

·
Registered
Joined
·
31 Posts
What you posted has the right PIDs. It all looks good. You may still want to consider getting it tuned so it will run better. There's quite a few tuners that work through e-mail transfers and you would use ECUFlash to rewrite the ROM.
Great. Thanks for your help!

Let me read up on tuning. This is my son's car. His mother was promised it would remain stock but maybe a tune for optimal fuel mileage would pass muster.
 

·
Premium Member
Joined
·
11,878 Posts
Discussion Starter #1,780
Great. Thanks for your help!

Let me read up on tuning. This is my son's car. His mother was promised it would remain stock but maybe a tune for optimal fuel mileage would pass muster.
Tuning is not just for HP improvement and go faster. It modifies the stock ROM to improve the overall performance. Better throttle response, slight changes in ignition timing, fueling and boost control can give you a much better car over stock.
 
1761 - 1780 of 1819 Posts
About this Discussion
1.8K Replies
243 Participants
tefloff
Subaru Outback Forums
Welcome to the Subaru Outback Owners Forum, we have tons of information about your Subaru Outback, from a Subaru Outback Wiki to customer reviews.
Full Forum Listing
Top