Lgt005 Posted August 30, 2017 Share Posted August 30, 2017 So I have a 2005 legacy gt with the 2.5 turbo engine. Only engine mods are turbo back exhaust, catless uppipe and a Cobb turbo inlet running stage 2 OTS MAP. Anyways I have been dealing with this very frustrating issue of my air fuel learning one being very high at 14.84 while idling and off throttle. Highway cruising it's about 6. I have replaced the turbo inlet, maf sensor, air fuel sensor and had a smoke test done. New sensors did not remedy the problem or the new turbo inlet. Shop performed a boost leak test and didn't find any. So now I'm not sure where to go from here. I'm tired of dumping money and not solving my issue. Where should I go from here? Is it possible the tune I am running is bad? It's a Cobb OTS stage 2 map. I have a couple datalogs I can send. Turner input is greatly appreciated! This is my DD and I am worried about driving anywhere with these out of whack reading. Please pm me if you can help me solve this issue! Thanks again Austin B Link to comment Share on other sites More sharing options...
Volta55 Posted October 3, 2017 Share Posted October 3, 2017 I am in the same boat... A/F #1 gets pinned at 14.99 after numerous ECU resets with replacements of turbo inlet, catless up-pipe with proper gaskets and sealing, stock panel filter, and no tune. I want to get this issue fixed before getting a tune; but i can not figure it out. Link to comment Share on other sites More sharing options...
robburns201 Posted October 3, 2017 Share Posted October 3, 2017 OK guys im in same boat also...But i have a tune coming up and Know that with my A/F learning @(A=7.14 B=12.0 C=14.0 D=13) That i must have a Boost/Vacuum leak some place....BUT my question is can i please have a General idea of where to look with someone evaluating my A/F learning numbers? I read someplace what a,b,c,d, meant but i cant find it again...Any help would be appreciated... Link to comment Share on other sites More sharing options...
solidxsnake Posted October 3, 2017 Share Posted October 3, 2017 Almost always if your A/F Learning A is pegged at +15%, you've got a vacuum leak somewhere. robburns201: the A/B/C/D refer to different airflow ranges. On a stock tune, A is 0-5.6 g/s, B is 5.6-10 g/s, C is 10-40 g/s and D is 40-80 g/s (I believe these are correct, though I think the 40 might be something else). Roughly, A corresponds to idle, B to very light throttle, and C/D to cruising. Anything above 30-40% accelerator input generally pushes the car into open-loop, where real-time A/F correction is disabled entirely. Here, the "Learning D" value is still used and applied to fueling, however. Link to comment Share on other sites More sharing options...
Volta55 Posted October 3, 2017 Share Posted October 3, 2017 here is a sample of an LV as of right now, for me, there are 0 timing corrections, and the A/F #1 (first vertical column of MAF g/s 0.0) is 14.99% and the other 3 columns are holding good at +/- 3% I have no idea where else to look for a vacuum leak lol. Ive smoked it plenty times too Link to comment Share on other sites More sharing options...
solidxsnake Posted October 3, 2017 Share Posted October 3, 2017 Might also be worth looking at what your A/F Correction looks like while you're idling (while your MAF is under 5.6g/s). If your A/F learning is pegged at +15% and your A/F correction is not pegged, then you're fine. If the correction is pegged at +25%, then you've definitely got some issues. Link to comment Share on other sites More sharing options...
Volta55 Posted October 3, 2017 Share Posted October 3, 2017 Might also be worth looking at what your A/F Correction looks like while you're idling (while your MAF is under 5.6g/s). If your A/F learning is pegged at +15% and your A/F correction is not pegged, then you're fine. If the correction is pegged at +25%, then you've definitely got some issues.Sorry for the reflection, but fuel correct is swinging around 7-9% while at stop light Sent from my SM-J700P using Tapatalk Link to comment Share on other sites More sharing options...
solidxsnake Posted October 3, 2017 Share Posted October 3, 2017 Sorry for the reflection, but fuel correct is swinging around 7-9% while at stop light Sent from my SM-J700P using Tapatalk Have you cleaned your MAF sensor at all? Also try wiggling the cables running to the MAF sensor. Could be contact issues or just a dirty MAF sensor (which can screw with fueling/metering at low flow rates but has less impact on higher flow rates). Link to comment Share on other sites More sharing options...
Volta55 Posted October 3, 2017 Share Posted October 3, 2017 Have you cleaned your MAF sensor at all? Also try wiggling the cables running to the MAF sensor. Could be contact issues or just a dirty MAF sensor (which can screw with fueling/metering at low flow rates but has less impact on higher flow rates). Very interesting.. I sprayed the IAT and and MAF a couple months ago but i will certainly do it again. I have always thought about this, but all the times I have smoked my motor I have done this http://cdn2.bigcommerce.com/server6100/2bdlcnn/product_images/uploaded_images/subaru-sti-wrx-ej-boost-leak-test.jpg?t=1422675329 which excludes the MAF. so possibly MAF gasket as well? has anyone had a bad MAF? any certain voltage I should be looking for? Link to comment Share on other sites More sharing options...
Perscitus Posted October 3, 2017 Share Posted October 3, 2017 Sorry for the reflection, but fuel correct is swinging around 7-9% while at stop light I would be more concerned with that AF Learn value and AF Learn swing range. Have you cleaned your MAF sensor at all? Also try wiggling the cables running to the MAF sensor. Could be contact issues or just a dirty MAF sensor (which can screw with fueling/metering at low flow rates but has less impact on higher flow rates).This too Link to comment Share on other sites More sharing options...
Volta55 Posted October 3, 2017 Share Posted October 3, 2017 I would be more concerned with that AF Learn value and AF Learn swing range. This too AF Learn swing range? yeah the -16 to +12.9 concerned me:spin: Link to comment Share on other sites More sharing options...
robburns201 Posted October 4, 2017 Share Posted October 4, 2017 Here is my AP on a cool morning today...At idle Link to comment Share on other sites More sharing options...
solidxsnake Posted October 4, 2017 Share Posted October 4, 2017 Here is my AP on a cool morning today...At idle That looks okay. Your B/C/D ranges will only potentially change when you're in them (i.e. when you're lightly accelerating, cruising, etc.). To really get a good picture you need to be logging your A/F Learning and A/F Correction while you're driving, while making sure you have very smooth throttle inputs. Link to comment Share on other sites More sharing options...
robburns201 Posted October 4, 2017 Share Posted October 4, 2017 They don't move much while driving...I will keep an eye on correction while driving next time and report back...thanks solidxsnake Link to comment Share on other sites More sharing options...
solidxsnake Posted October 4, 2017 Share Posted October 4, 2017 They don't move much while driving...I will keep an eye on correction while driving next time and report back...thanks solidxsnake It takes a sustained period of time for them to move, along with sufficient correction. For instance, if I'm cruising on the highway at around 20 g/s MAF, my AF Learning C (which covers the 10-40 g/s range) is at +10%, and my AF Correction is hovering around -12%, then if I stay in that range (and don't drop below 10 g/s or above 40 g/s), then after some time the ECU will start subtracting from the AF Learning C value. Assuming ideal conditions and the numbers I just gave, eventually AF Learning C should settle around -2%, at which point AF Correction should hover around 0%. In a perfect world (with perfect environmental conditions, and perfect sensor calibrations, etc.), the sum of AF Learning and AF Correction would always be 0%. If you want to see the ECU learning without moving, reset the ECU and then monitor AF Learning A and AF Correction while the engine is idling. You should see what I'm talking about. The key point is that there's a delay before the ECU starts modifying its learned values, and that delay resets every time you change AF Learning ranges. Also, if AF Correction is low (I'd say less than ±5%), then the ECU won't really play with the AF Learning values, at least in the B-D ranges. I'm not entirely certain all of the conditions, but that's what I've observed. Link to comment Share on other sites More sharing options...
robburns201 Posted October 4, 2017 Share Posted October 4, 2017 Will do...Thanks for the Help and i will report (post) my logs... Link to comment Share on other sites More sharing options...
Volta55 Posted October 4, 2017 Share Posted October 4, 2017 Just did a quick log, pull and cruise around the work neighborhood Idle.csvPull.csv Link to comment Share on other sites More sharing options...
solidxsnake Posted October 4, 2017 Share Posted October 4, 2017 Just did a quick log, pull and cruise around the work neighborhood Is the picture above of your car (with the STi intake manifold)? If you have modifications like that and haven't gotten a tune, that's definitely a problem. You're getting quite a bit of knock in that partial pull log. If you're stock besides the catless up-pipe, you shouldn't need a tune. If you've done more mods, though, that's definitely something we'll need to know. Link to comment Share on other sites More sharing options...
Volta55 Posted October 4, 2017 Share Posted October 4, 2017 Is the picture above of your car (with the STi intake manifold)? If you have modifications like that and haven't gotten a tune, that's definitely a problem. You're getting quite a bit of knock in that partial pull log. If you're stock besides the catless up-pipe, you shouldn't need a tune. If you've done more mods, though, that's definitely something we'll need to know. No STI intake manifold... everything stock except catless up. trying to fix these levels so i can get an e-tune lol edit: this is with a 5EAT in sport mode.. data zap looks sweet https://datazap.me/u/volta55/log-1507132629?log=0&data=2-4-5-6-7-10-11-12 Link to comment Share on other sites More sharing options...
Volta55 Posted October 4, 2017 Share Posted October 4, 2017 The only thing I can think of is that I remove the silencer/milkjug... but that is pre-MAF Link to comment Share on other sites More sharing options...
solidxsnake Posted October 4, 2017 Share Posted October 4, 2017 The only thing I can think of is that I remove the silencer/milkjug... but that is pre-MAF That's not stock then, and that will throw off your MAF scaling. Link to comment Share on other sites More sharing options...
MilesA Posted October 4, 2017 Share Posted October 4, 2017 The intake milk jug is a Helmholtz resonator. This is not just (or primarily) a silencer. It is intended to dampen air pulsations in the intake. Would be interesting to put it back and see what effect that has. Link to comment Share on other sites More sharing options...
solidxsnake Posted October 4, 2017 Share Posted October 4, 2017 The intake milk jug is a Helmholtz resonator. This is not just (or primarily) a silencer. It is intended to dampen air pulsations in the intake. Would be interesting to put it back and see what effect that has. Correct. For the same reason even using a different panel filter will cause the car to incorrectly meter fueling, removing the silencer can also cause issues. The MAF sensor is extremely sensitive to the quality of the air flowing through it (with regards to how turbulent it is), and changing anything upstream of it will perturb how it operates compared to how the engineers at Subaru designed it. Unless one knows what they're doing (i.e. have run simulations and/or have re-calibrated the MAF sensor for different conditions, both of which GrimmSpeed did for their intake), they're best off leaving things stock. Link to comment Share on other sites More sharing options...
Volta55 Posted October 5, 2017 Share Posted October 5, 2017 Thanks for all this help, solidsnake Can I make a home-made one? or are the internal dimensions of the silencer super critical? for what its worth, my A/F #1 Learn % was pegged at 14.99 before the silencer removal. to be honest, once I removed it, i did not notice any noise difference until a heavy downshift on the highway ( an annoying loud drone sound ) so i'm kinda looking forward to putting some kind of silencer back on. Link to comment Share on other sites More sharing options...
solidxsnake Posted October 5, 2017 Share Posted October 5, 2017 The dimensions are critical, I'd just drop the stock one back in. Link to comment Share on other sites More sharing options...
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