2013 WRX AF Learning 1 at +25% at idle

[muertos]

Originally Posted by enduroxt

OK. mmmh. This is strange. How long has the car been showing +25% ? Oh, what mods do you have on this car? Stock tune? Stock air intake?

about a week and a half or so. I'll ensure the MAF sensor is working like it's supposed to.

Mods:

• Cobb SF intake
• NVIDIA 3in turbo back exhaust
• Built stock motor with forged internals, STI crank

All Aspects tuned it and built the motor. I've definitely considered having them look at it. Admittedly I'm inexperienced, but it is fun to try to figure out what's wrong with it myself. When I first started troubleshooting this, the car would lose some power around 5,6k RPM as initially described, but overall felt driveable around town. I took the MAF sensor out first and hit it with isopropyl, which I later found you should use MAF cleaner. I used a q-tip liberally all around the sensor part of it too, which I understand you should not touch. It did not really appear dirty, but perhaps I messed it up. And then I moved on to the upstream/downstream O2 sensors and replaced those. Ever since those changes the car has ran considerably worse, like I don't even like driving it around the block, just runs very rough all around. I'm fairly sure I messed up the MAF. I'll definitely dig deeper. Appreciate the insight and help so far!

* Registered users of the site do not see these ads.

[muertos]

Also, my bad, I think I mislead with the title of this post. Pretty sure it's the AF Correction 1 (real time trims) that's been stuck at 25% at idle and that ain't good

[muertos]

Still seems like there's a vacuum leak, somewhere, just because real time fuel trim (AF Correction 1) is maxed out at +25% at idle at running temps

[muertos]

I just performed the simple vacuum leak test and recorded it. I blew into the vacuum hose that connects the intake manifold to the BPV. In the video, I blew into the hose twice. Each time I held the pressure in for about 5 seconds or so and the pressure seems to hold and I hear no leaks. Video: https://photos.app.goo.gl/ZrsxbFPBgW5ZeM8B8

[enduroxt]

Are you sure the 02 sensor is seating right and no leak around it?
Suppose your idle learned fuel trim is zero. If the idle AF correct stays at +25%, it will eventually affect the AF learn idle fuel trim where the latter will slowly creep to +25%. On my car, +15% (or -15%) is the max (min) it can reach.

[enduroxt]

Are you sure the 02 sensor is seating right and no leak around it?
Suppose your idle learned fuel trim is zero. If the idle AF correct stays at +25%, it will eventually affect the AF learn idle fuel trim where the latter will slowly creep to +25%. On my car, +15% (or -15%) is the max (min) it can reach.

[subaru_gc8]

would have to say you hav a massive leak in the intake tack. get a smoke leak detector it is the easiest way,

[blue sedan]

Originally Posted by muertos

Still seems like there's a vacuum leak, somewhere, just because real time fuel trim (AF Correction 1) is maxed out at +25% at idle at running temps

Check the EVAP solenoids .there are 2 of them in front/under intake manifold .2 hoses go to each solenoid .if the solenoid is stuck open you'll get that AF correction at idle ...
While the car is idling disconnect one hose and put finger over it and watch the AP AF correction to see if it goes down to normal .try each hose .
It happened to me ,the same issue .Good luck !
Any questions ask

[tmullins]

Hello, I have a 2011 with the exact same issue and have been chasing it for months now, still no resolution.

Current Mods:
- GrimSpeed intake
- Perrin TMIC
- Cobb turbo back catted exhaust
- AEM 340lph pump
- 6 speed swap
- Custom e-tune from Cryotune Performance

I have been running the same configuration and tune (minus the 6 speed swap and fuel pump) for years now with no issues. I did the 6 speed swap a couple months ago and on the first test drive I started getting some backfire on high rpm 1-2 and 2-3 shifts, so I logged some 3rd gear pulls and sent them to the tuner. I'm reaching 18psi boost, but fuel is sitting at 13.x until I get near readline when A/F finally catches up to 11.x. Needless to say, I stopped getting into boost when I saw that.

When I reset learning through the AP, it runs great for the first 15-30 minutes of normal driving then A/F Learning 1 sits at 0 for a while, then creeps back up to +25%

I have:
1. Verified the battery is good and alternator is putting out 14.7v under load
2. Smoke tested it for vacuum leaks 5x, found two small leaks at the TGV dust covers and fixed those. No change in readings.
4. Replaced the MAF sensor, A/F sensor, and O2 sensor with new OEM sensors.
5. Replaced the fuel pump with AEM 340lph pump and new OEM regulator
6. Bypassed the EVAP solenoids and vented cannister to atmosphere to test, and getting same same readings.

The only thing I haven't replaced at this point is the fuel rail and injectors or the TGVs. I'd rather not do that since I'm not expecting to add any more power.

Getting quite frustrated and tired of throwing money at it, but can't have it run lean like it is.

[enduroxt]

What did Cryo suggest after all the parts you replaced?

[muertos]

I ordered a smoke machine. Thanks for the additional information guys! Will report back.

[tmullins]

He's suggesting I still have a mechanical problem somewhere in the system causing the lean condition. I'm planning to replace the PCV valve tonight even though I have no confidence it will help the situation. My next step is to check my ego and take it to someone who's smarter than me.

[enduroxt]

Clearly frustrating. Is the MAF wiring harness still original? I had to get new MAF pigtail wires from iwire as the connection at the MAF was getting worse overtime (i.e. poor ground). But this resulted in a rich condition, not lean. It happened on both cars we own (05 and 06 OBXT). Now back to +/-2%.

[enduroxt]

Also, I should mention that when I troubleshoot this stuff, I like to keep the car idling, take my phone with me running the BtSsm app, and poke around hoses, wires and stuff and see what the A/F correction does when I touch something. That's how I identified the issue with the MAF connection. This is in addition to doing the basics as you guys have done (i.e checking for vac leaks)

[tmullins]

Originally Posted by enduroxt

Also, I should mention that when I troubleshoot this stuff, I like to keep the car idling, take my phone with me running the BtSsm app, and poke around hoses, wires and stuff and see what the A/F correction does when I touch something. That's how I identified the issue with the MAF connection. This is in addition to doing the basics as you guys have done (i.e checking for vac leaks)

That’s a good idea. Wiring harness is original and last I checked, sensor voltage was in range. Under load and out of boost, AF learning sits at 0 and the car seems happy. It’s only when not under load that it creeps up to +25%.

[thewraith420]

Originally Posted by enduroxt

When the A/F corrections are positive, that means the engine is running lean, so the ECU compensates by sending more fuel (here >25%). You must have some major vacuum leak somewhere between the MAF and the turbo. Carefully check for this first and don't push the car.

blow some smoke into a vacuum line I used the line for the bypass valve and also cover up your intake filter make sure nothing comes out of it

[muertos]

Originally Posted by thewraith420

blow some smoke into a vacuum line I used the line for the bypass valve and also cover up your intake filter make sure nothing comes out of it

Just performed a quick test with the smoke machine. I blew it into the bypass valve vacuum line. Blew smoke for about 2,3 minutes. Did not see any obvious smoke coming out of anywhere (prolly gonna test at night too). The pressure gauge reads 0 psi the whole time, so the system is not holding pressure still.. which seems like I have a huge leak somewhere if that's the case. I'm just afraid to push the smoke machine too far with pressure

[muertos]

duplicate post

[muertos]

Did another smoke test, this time pushed the pressure a bit more, and now I see an area where smoke is coming out: https://imgur.com/gallery/6ktCiFh

Smokes comes from the passenger side TGV / Intake Manifold <--> head mounting area. Taking the intake manifold off seems fun

[enduroxt]

Upper intake manifold gaskets leaking? I can't see smoke on our pics though.

[enduroxt]

You could also have the engine running, and spray some carb (or MAF?) cleaner around these areas and see if the idle changes. I think cold idle would be better than warm since the rpm would be higher, and therefore the intake would suck more air.

[Router Rob]

I just fixed a leak on a wrx with the smoke coming from the same area. It was the fitting on the block vent got brittle and cracked. Just had to pull the intercooler to get to it.

[muertos]

I grabbed a new perrin turbo inlet and swapped it with the old stock one. There was a decent crack where the stock turbo inlet pipe mates with the turbo, so I figured that may be the culprit. Smoke tested again after everything has been reinstalled and I still have smoke coming out of the same area. It appears smoke was coming right out of the passenger side TGV out of some little metal plate with a couple screws on it. I think I'd like to be super definitive about where that smoke is coming from, so will take time to set up for filming, then probably rip the intake manifold off.

[enduroxt]

Originally Posted by muertos

I grabbed a new perrin turbo inlet and swapped it with the old stock one. There was a decent crack where the stock turbo inlet pipe mates with the turbo, so I figured that may be the culprit. Smoke tested again after everything has been reinstalled and I still have smoke coming out of the same area. It appears smoke was coming right out of the passenger side TGV out of some little metal plate with a couple screws on it. I think I'd like to be super definitive about where that smoke is coming from, so will take time to set up for filming, then probably rip the intake manifold off.

keep us posted. I am curious.

[enduroxt]

Originally Posted by Router Rob

I just fixed a leak on a wrx with the smoke coming from the same area. It was the fitting on the block vent got brittle and cracked. Just had to pull the intercooler to get to it.

Do you have a pic for it?