Help! Very high a/f learning

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

It sounds like you check about everything, your next step is to data log and have a tuner look at.

It is rare to not find ANY boost leaks.. I had a similar issue recently, turned out to be the plenum gaskets. Egr is working correctly?

I also thought it was weird not to find any vacuum leak on a 12 year old car. But the shop did call me while it was hooked up and said they couldn't find any and offered to let me come and see for myself but unfortanatly I was at work and could not make it over to the shop at that time. I have not checked the egr yet but I will do that soon.

 

Unfortanatly I don't have a tuner to send my data logs to because I have never been pro/Dyno or e tuned before. I wanted to get this issue fixed so I could get someone to tune it. I don't know any tuner that would want to mess with the car now having high a/f learning.( probly tell me to fix that issue first then they will tune it) But if there are any tuners that would take a look at my data logs and stuff I'd be happy to send them to you! Is it possible for someone to check the map and make sure there's nothing weird in there?

Check fuel pressure - see the procedure in the vacay pics

 

Use BTSSM to monitor for sub-threshold misfires at various RPM levels

 

Consider a smoke test of the exhaust system. Do you get any whistling under boost? What brand up-pipe do you have?

I can't hear any whistling but my exhaust is pretty loud. Grimmspeed upipe. Did not do an exhaust smoke test. Would that show in a vacumme smoke test? I have crawled under the car to check for any exhaust leaks around the uppipe and manifold but could feel or find any.

 

I apologize for my stupidity but where can I find that procedure for the fuel pressure? Im not sure what the vacay pics are. Thanks!

 

Is it possibly my fuel pump is going bad or I have a bad fpr? If so if there a way way to find out?

Go back to your stock map and cruise around for a while, and watch your AF learning.

 

If it's no longer a problem, then the OTS map is your issue.

Go back to your stock map and cruise around for a while, and watch your AF learning.

 

If it's no longer a problem, then the OTS map is your issue.

 

I'll give that a try and report back.

Go back to your stock map and cruise around for a while, and watch your AF learning.

 

If it's no longer a problem, then the OTS map is your issue.

 

OP: Do NOT do this! Running a stock map with a free-flowing downpipe is a clear path to #YNANSB.

I can't hear any whistling but my exhaust is pretty loud. Grimmspeed upipe. Did not do an exhaust smoke test. Would that show in a vacumme smoke test? I have crawled under the car to check for any exhaust leaks around the uppipe and manifold but could feel or find any.

 

I apologize for my stupidity but where can I find that procedure for the fuel pressure? Im not sure what the vacay pics are. Thanks!

 

Is it possibly my fuel pump is going bad or I have a bad fpr? If so if there a way way to find out?

 

The GS has a flex section, so probably not your problem. A smoke test of the intake system will not smoke test the exhaust system. Exhaust leak is not a primary suspect anyway if you're not whistling.

 

Search this site for "vacation pics", you'll find the link right quick.

 

The fuel pressure test will diagnose the pump and regulator. Easy & quick if you have a fuel pressure tester ($50 @ AutoZone; do NOT get the Harbor Freight POS).

If your learning at idle is high (but not pegged at 15%) but the rest look fine and you're not getting knock at mid-to-high throttle/loads, then you're probably fine. Just because you have high learning values doesn't mean you're running rich/lean. As long as your learning isn't pegged at its max value (I believe +/- 15%), then the ECU will hit hits fueling targets.

 

That said, a high AF learning in the lower flow ranges generally indicates a vacuum leak. It could also just be a tune that's not well suited to the car. OTS tunes can't account for everything.

OP: Do NOT do this! Running a stock map with a free-flowing downpipe is a clear path to #YNANSB.

Lmfao...

 

What a tool

I'll give that a try and report back.

Ignore the people who tell you that you're going to blow up your car.

 

Start the car and let it idle until it hits operating temp.

 

You'll know very quickly if it's the map

Ignore the people who tell you that you're going to blow up your car.

 

Start the car and let it idle until it hits operating temp.

 

You'll know very quickly if it's the map

 

Can vouch. You can even drive it around a little bit, as long as you stay out of open-loop fueling, the car will be fine. Just don't accelerate quickly or give it a lot of throttle input. If you have gauges set up with the AP, keep your Calculated Load under 1 g/rev and it should stay in closed-loop.

For mt exhaust leak I jacked up the car, soaped all the gaskets on the DP, UP, exhaust mani, and fired up the car. Started bubbling at the EM crossover. Double thick grimm gaskets and good to go.

Thanks guys! I'm going to check the fuel pressure, double check the exhaust isn't leaking and check if it's the map. I'll report back once I get a chace to do any of these or if anything else changes. Meanwhile here are my learning values as of last night on my way home. Then pulling into my parking spot (after this picture was taken ) learning A went to 15 (max) then slowly stated dropping down to 10. Idk if this means anything.

 

It may also be worthwhile keeping an eye on "AF Correction 1" while you're driving in closed-loop (cruising, low throttle, idling). If that's pegged at +/- 25%, you've definitely got a major problem. If it stays near zero for a steady-state condition, then your trims shouldn't move around. If it stays at a relatively large number (generally above 5% or so) for a long enough period of time at a steady state condition, one of your AF learning numbers should start moving.

Good info! I'll defiantly keep an eye on that. I did notice that my a/f correction 1 jumps around a lot when on steady throttle. Is that normal or should it stay prettt constant?

when you say 'turbo back exhaust' mod, what do you really mean? In other words, what kind of downpipe do you have?

 

Also, if you have really confirmed that there are no vacuum leaks, then it may be worth trying what I did before: I let the car idle, opened the hood, took my phone with the btssm app running (in your case the AP) and placed it in the engine bay, and then started to wiggle the maf wires; while I was doing this I stared at the A/F correction variable on the app. Lo and behold, I did have an issue with my maf wires! Each time I was wiggling or touching the wires, the A/F correction was going all over the place and you could also hear the engine trying to adjust to the change of conditions... Worth trying just in case.

I have a 3in catless invidia down pipe. Divorced wastegate. And then a 3in cat back that splits to two 2.5 in I think pipes to 2 mufflers one on each side. Also have the catless grimmspeed up pipe.

 

Thanks! I'll deffinatly give that a try. I never even thought about that.

Edited August 31, 2017 by Lgt005

ok. then definitely stage 2.

 

how is your IAM? Still at 1? Can you pull an 'LV' with the AP? Just want to know if you have one or more cells with recorded FLKC values.

Bringing this thread back from the dead. The OP never posted a solution and I'm having the same problem!

2005 LGT, Cobb stage 2 OTS,new MAF,new-ish O2 and air filter (4K miles)

A/F learning pegged at 15 in line A, DAM at 1, no timing corrections. AFR stays at 14.7 at idle and throughout the rev range. Idles and drives great,it's the reading that's bothering me

Oh,it's been smoked with no leaks found

Edited January 15, 2021 by zactek
Extra info

If you are sure there are no vacuum leaks, then I would adjust the MAF scaling.

If you are sure there are no vacuum leaks, then I would adjust the MAF scaling.

 

I haven't changed anything with the tune or any parts in the last 2 years,why would my maf scaling be suddenly off that much?

Would an exhaust leak affect the 02 sensor that much to read

lean and add fuel?

I haven't changed anything with the tune or any parts in the last 2 years,why would my maf scaling be suddenly off that much?

Would an exhaust leak affect the 02 sensor that much to read

lean and add fuel?

 

It wouldn't, and it's absolutely idiotic for some to suggest such.

 

Many years ago, my wife's FXT suffered from a high AF Learning A value. It was a tear in the intake boot after the MAF. You don't necessarily need to have a vac leak or an exhaust leak.

Our issue was solely because the intake boot would pull open slightly at idle, but once the engine torqued over slightly from being out in gear or driven, it would seal the leak and show no other signs of a problem.