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Why am I so lean?


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Car was tuned for everything I have on it in the fall. Was running great. Every week or so I go and let it run for 20 min just to keep the battery charged and get condensation out. But now my af learning and correction are all wacky. I tested for leaks with pressure and smoke. Changed my maf and my front o2 sensor is new. Idk what else to do. I keep pressure testing and find nothing. e795f0b323919fdddc9d76f327a69dbb.jpg

 

It’s adding a ton of fuel and idk why it would be if there aren’t any leaks

 

 

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I just put my old maf back in and now this fbaf1112a599944c680208d42548257c.jpg

 

So it went from adding a lot of fuel to pulling a little bit of fuel. Does this mean I was tuned in a bad maf probably? I believe I changed it because it was going -12 but with the new one it’s +25

 

 

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My car was tuned on a bad MAF and sent CELs off with no rhyme or reason, however my car would stall a lot. Put a new MAF in and go for a tune, perhaps? When I put the new MAF in I ran pretty lean until tuned on the new one.

 

 

 

Yeah it’s gotta be the maf. When I switched from the one I tuned on to the new one the numbers changed drastically. But if it’s set up for the bad maf I would assume a new one would send the numbers the other way like it did.

 

 

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Did you reset the ecu after the maf swap? If not you should so it can begin a relearn. Check with your tuner he’ll probably just need a couple of datalogs to make the necessary adjustments to the tune.

 

 

 

I actually did not. I’ll reset it when I get home and let it idle and see what has changed.

 

 

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Well just reset it with the new maf. Went to +12 this time instead of +25. I guess I’ll just have to put the bad maf back in for the time being and get the car retuned. Kind of annoying. Maybe the maf scaling is off or something. At least my wide band is still sitting on low 15s and my accessport is 14.7. I guess as long as it makes the corrections for now I should be fine

 

 

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Since WOT is open loop and isn’t using sensors (maf & o2) I’d wonder if maybe you have a bad injector. How’s your oil smell?

 

 

 

Just went out and smelled it. I guess I smells a little like fuel. That oil is only about 500 miles old too

 

 

Right before I got the rich wot I should add that I did a free air calibration on my wideband. Before that it was always mid 10’s wot. So maybe I was getting Incorrect WB readings during the tune and now that I calibrated it. It is showing 8 and 9. Maybe too much fuel was added initially but wasn’t realized because the wideband was reading wrong?

 

Idk maybe I’ll just buy some 1050x injectors and get a dyno tune. I have a vf52 so maybe I could benefit from the injectors even if the stock ones I have are actually fine. I’d hate to get tuned and them say the injector is bad and I lose my deposit and have to come back anyway.

 

 

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Edited by Ares3985
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Looking back at earlier posts I see it’s been adding fuel not pulling it so if was a sticky injector I’d think it would pull fuel to compensate when in closed loop. Was it etuned? Reason I ask is the afr is based on existing sensors with etune whereas dyno tune would have a probe in the tailpipe for afr and I think the tuner would’ve noticed a discrepancy. How’s your wideband compared to the afr1 reading on the AP? I know the AP won’t go less than 11.1 or so at WOT but at other times is it pretty close?
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Looking back at earlier posts I see it’s been adding fuel not pulling it so if was a sticky injector I’d think it would pull fuel to compensate when in closed loop. Was it etuned? Reason I ask is the afr is based on existing sensors with etune whereas dyno tune would have a probe in the tailpipe for afr and I think the tuner would’ve noticed a discrepancy. How’s your wideband compared to the afr1 reading on the AP? I know the AP won’t go less than 11.1 or so at WOT but at other times is it pretty close?

 

 

It is adding fuel now but it was pulling fuel when I had the old maf in. It was at about -12 learning at idle or cruise. That’s why I changed it but it sent the readings the complete other direction

Yes it was etuned. The wideband at idle settles at 15.8 while the accessport holds 14.7. It was tuned at idle and cruise using the accessport datalogs. Wot was tuned using the datalogs and wideband.

 

 

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I guess your O2 sensor needed calibration when you went for the tune, and your MAF was going bad. The tuner was just going off your logs, so it's not his fault, but you should really have calibrated the O2 before the tune. I would get in touch with the tuner and ask for a retune given the recalibrated O2 sensor, and new MAF, he would probably give you a break on the price. But it sounds like your wideband is still off if there's a full point difference at idle compared to your upstream O2 readings. I'd double check your free-air calibration before getting in touch with the tuner.
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I guess your O2 sensor needed calibration when you went for the tune' date=' and your MAF was going bad. The tuner was just going off your logs, so it's not his fault, but you should really have calibrated the O2 before the tune. I would get in touch with the tuner and ask for a retune given the recalibrated O2 sensor, and new MAF, he would probably give you a break on the price. But it sounds like your wideband is still off if there's a full point difference at idle compared to your upstream O2 readings. I'd double check your free-air calibration before getting in touch with the tuner.[/quote']

 

 

 

I actually replaced the o2 during the tune. I had a failure part of the way into the tune. I’m going to a better place next month for an actual dyno tune. The etune scene is not for me. Takes too long and results were not optimal.

 

 

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Post a current log at idle and cruise with the parameters that you used for the etune.

 

Here is a short idle log but the learning was positive during it. I havent changed my logging parameters since the tune. I havent been able to go for a cruise yet as i am doing some other work on the suspension. Maybe you will see something in this log.

 

 

added a cruise log. 50ish mph very light throttle and the correction is all over. during the cruise i saw the af correction go from -25 to +25. now i am getting slight knock too. i never had these issues before the tune and now they are all just popping up at once. Th ecar has not been modified since. it has been sitting in the garage the majority of the time

Idle.csv

cruise.csv

Edited by Ares3985
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I’m not seeing anything out of the ordinary on that log other than the water temp was a little low. Might just be you took the log after a bit of warm up idle but I’d keep an eye on that to make sure that you’re in the ~190* range after driving a bit since the ecm monitors water temp as well. Others may chime in if they see something I didn’t. The fuel adding may be due to added air. Have you smoke tested or boost leak tested? I’d recommend having a new o2 and maf on hand for the tune day. Buy them somewhere like amazon where you can return if you don’t need. I’d also do or have the tuning shop do a smoke test prior to the tune. I’ve noticed my learning 1 to be adding or pulling more than +/-8 on occasion and was told by the shop that changes in weather, iat and other variables can cause that and not to worry. (I’m tuned for speed density though. Not sure if that matters) Most of the time I’m between 0 and +/- 5 or 6. Someone on here referred to the Cobb AP as “Cobb Anxiety Port” which I find fitting as I tend to watch it too much. It sounds to me like you haven’t been driving the car much (correct me if I’m wrong) and if so since the reset it will take some time to learn trims. If you’re not having significant knock events and your DAM is staying at 1 then the ecm is doing what it’s supposed to in making corrections.

 

Not sure why the wideband is off by that much though unless the sensor is on its way out. Is the sensor in the bellmouth of the downpipe? That’s where mine is and I get a reading very close to my AFR1 on the AP. Don’t replace the wideband sensor until after the tune. The tuner will tell you if its off compared to the dyno.

Edited by DaveWaters
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Post a current log at idle and cruise with the parameters that you used for the etune.

 

I’m not seeing anything out of the ordinary on that log other than the water temp was a little low. Might just be you took the log after a bit of warm up idle but I’d keep an eye on that to make sure that you’re in the ~190* range after driving a bit since the ecm monitors water temp as well. Others may chime in if they see something I didn’t. The fuel adding may be due to added air. Have you smoke tested or boost leak tested? I’d recommend having a new o2 and maf on hand for the tune day. Buy them somewhere like amazon where you can return if you don’t need. I’d also do or have the tuning shop do a smoke test prior to the tune. I’ve noticed my learning 1 to be adding or pulling more than +/-8 on occasion and was told by the shop that changes in weather, iat and other variables can cause that and not to worry. (I’m tuned for speed density though. Not sure if that matters) Most of the time I’m between 0 and +/- 5 or 6. Someone on here referred to the Cobb AP as “Cobb Anxiety Port” which I find fitting as I tend to watch it too much. It sounds to me like you haven’t been driving the car much (correct me if I’m wrong) and if so since the reset it will take some time to learn trims. If you’re not having significant knock events and your DAM is staying at 1 then the ecm is doing what it’s supposed to in making corrections.

 

Not sure why the wideband is off by that much though unless the sensor is on its way out. Is the sensor in the bellmouth of the downpipe? That’s where mine is and I get a reading very close to my AFR1 on the AP. Don’t replace the wideband sensor until after the tune. The tuner will tell you if its off compared to the dyno.

 

 

 

i added a cruise log to the last post dave. so yes it just wasnt fully warmed up. i have boost leak and smoke tested so many times i cant even count and found nothing. wideband is in the bellmouth. i just drove the car now and i had a few knock events. something which i have not had before now. dam stayed at 1 tho and there was no knock learn. i changed the o2 during the tune and just changed the maf a few weeks ago thinking these were both issues. im seriously stumped here. sometimes i drive and have crazy negative correction and at the same throttle i can have crazy postive correction. there just isnt anything consistent.

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Found a small exhaust leak on my downpipe to turbo. Nothing significant. Fixed it and same results. Also found a leak on the wastegate arm. I don’t think this can be fixed short of pulling the turbo and rebuilding it. This was also a small leak. I’m not sure if this would give me any of the issues I’m having though. 59a14e3c7b06fc6acafa41127b0681f2.jpg

 

 

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I think it’s in the tune. I went through an etune where I was getting I want to say big positive corrections at cruise (I cant quite recall for sure) and the tuner was telling me its has to be a leak but I could never find one.

 

BTW I only say pick up the maf and o2 just in case. Last thing you want is the tuner saying there’s a problem with one or the other. When is your tune scheduled? I’m looking forward to the outcome.

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I think it’s in the tune. I went through an etune where I was getting I want to say big positive corrections at cruise (I cant quite recall for sure) and the tuner was telling me its has to be a leak but I could never find one.

 

BTW I only say pick up the maf and o2 just in case. Last thing you want is the tuner saying there’s a problem with one or the other. When is your tune scheduled? I’m looking forward to the outcome.

 

 

 

I recall my etuner saying the same thing. He first told me o2. Then it was a leak and then he told me it was fuel pressure. Then all of a sudden none of it was an issue after I tested everything and it came back good. I just don’t understand why it’s all coming back now all of a sudden. Hopefully the new tuner can do better. They are a reputable shop here in jersey so.

 

 

Yeah I think I’m gonna buy another maf and o2. I’ll have 3 mafs and 2 o2. Lol. I might get some injectors too so my duty cycle isn’t so high. As long as they will send me a base map of course.

 

Tune is on the 20th but I’m going to have a pretune inspection done by them on the 14th. I smoked it again today so I know it’s gonna be fine. Just a little more peace of mind.

 

 

 

 

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