[dan_88]

Best start looking at a upgraded LPFP 😂

[BM3Rrrr]

Originally Posted by 335e92tx

Id start with only fronts. I have not ever gotten a clear understanding of how Back o2s are involved in the Trim process for N54s. No other closed loop system uses rear O2s to influence trims that I know of. They are used to assess cat efficiency by comparing front o2s to post cat readings..

Thanks. I’ll start with the fronts then.
I assume if that doesn’t correct the issue the next thing to look at will be bank 1 injectors?

[type-dRew]

Originally Posted by 335e92tx

Id start with only fronts. I have not ever gotten a clear understanding of how Back o2s are involved in the Trim process for N54s. No other closed loop system uses rear O2s to influence trims that I know of. They are used to assess cat efficiency by comparing front o2s to post cat readings..

My last car(hyundai sonata 2.0 turbo) actively used the rear o2 for fueling adaptations with factory widebands and closed loop wot fueling.

My rear o2 code was turned off in my tune but if i unplugged or removed the sensor, I would have outrageous fuel trims. But no codes.

I have been told this is NOT how the BMW works(so much that you could just delete the rear o2s when tuning it) but it did catch me quite off guard that I picked up 7mph in the 1/4 mile by reinstalling my rear o2 after not being able to figure out where my power went from a catless midpipe swap(where I left the o2 on the old one not thinking i needed it) and should have picked up power but lost all of it(and 20+% STFT while it was trying to adjust). I drove it on the street for two weeks without just to see if it just needed to learn but no, it absolutely needs it, ran terribly rich and no power without and all was perfect(immediately) with it plugged in.

Weird setup.

[RSL]

AFAIK and in the most basic terms, rears essentially define lambda = 1.0 for the primaries. If a bad rear sensor/reading skews stoich set point from reality, fueling and trims are going to change.

With no rear O2 at all, it was likely stuck in a safety, which obviously isn't ideal lol

[type-dRew]

Originally Posted by RSL

AFAIK and in the most basic terms, rears essentially define lambda = 1.0 for the primaries. If a bad rear sensor/reading skews stoich set point from reality, fueling and trims are going to change.

With no rear O2 at all, it was likely stuck in a safety, which obviously isn't ideal lol

Would you say its the same when tuned?

Because I have a rear o2 code and plan on tuning soon, that'll kill the code but if they arent reading correctly and its affecting mixtures, id like to replace them when I do downpipes. And as it was I was only planning on putting it new primaries and just leaving the 2nd ones original.

Ill take advice on that

[RSL]

Originally Posted by type-dRew

Would you say its the same when tuned?

Because I have a rear o2 code and plan on tuning soon, that'll kill the code but if they arent reading correctly and its affecting mixtures, id like to replace them when I do downpipes. And as it was I was only planning on putting it new primaries and just leaving the 2nd ones original.

Ill take advice on that

Operation is the same, tuned or not. There are different codes for different problems. A tune likely just disables the cat efficiency codes from showing, that doesn't effect other codes for O2s or prevent them from working. The problem with the fronts and rears having a tie, is that it can make it difficult to determine which is the root cause/problem sometimes. That's assuming it's actually the O2s and not an issue elsewhere (leaky injectors, etc.).

If you have a code specific to the rear O2 sensor though (2CE something? I forget what they are), it's probably a real rear O2 problem. First thing I'd do with any O2 code/trim issue is delete the codes and reset adaptations, then monitor. If it pops up immediately, it's probably a hardware problem. If it takes some time to return, could just be having a problem over time from unconverted exhaust.

[type-dRew]

Originally Posted by RSL

Operation is the same, tuned or not. There are different codes for different problems. A tune likely just disables the cat efficiency codes from showing, that doesn't effect other codes for O2s or prevent them from working. The problem with the fronts and rears having a tie, is that it can make it difficult to determine which is the root cause/problem sometimes. That's assuming it's actually the O2s and not an issue elsewhere (leaky injectors, etc.).

If you have a code specific to the rear O2 sensor though (2CE something? I forget what they are), it's probably a real rear O2 problem. First thing I'd do with any O2 code/trim issue is delete the codes and reset adaptations, then monitor. If it pops up immediately, it's probably a hardware problem. If it takes some time to return, could just be having a problem over time from unconverted exhaust.

2CE is what mine popped, right after we installed an updated cat back on the car it popped, its been cleared and adaptation reset twice. It pops back immediately. So seemingly an o2 issue.

Guess i'll plan on getting new rear o2s to go with the downpipes along with primaries.

[RSL]

I'm not sure how a catback could effect the rear O2 in the DPs honestly. Still on stock DPs with a catback only?

Usually, if an O2 code comes up right after R&R and doesn't go away with a reset, the O2 was damaged in the process or potentially the harnesses were switched when plugged back in (car usually runs like crap). I would assume none of the O2s were even touched yet then if it was just a catback install?

Did they beat the hell out of the exhaust at any point to get it off? Maybe just a shock on the attached pipes injured it in some way. It's either that or something completely different is causing it, but not sure what. Ground? Is there a ground strap on the stock exhaust that was removed possibly?

[type-dRew]

Originally Posted by RSL

I'm not sure how a catback could effect the rear O2 in the DPs honestly. Still on stock DPs with a catback only?

Usually, if an O2 code comes up right after R&R and doesn't go away with a reset, the O2 was damaged in the process or potentially the harnesses were switched when plugged back in (car usually runs like crap). I would assume none of the O2s were even touched yet then if it was just a catback install?

Did they beat the hell out of the exhaust at any point to get it off? Maybe just a shock on the attached pipes injured it in some way. It's either that or something completely different is causing it, but not sure what. Ground? Is there a ground strap on the stock exhaust that was removed possibly?

Just swapped to another factory catback with less miles and different configuration. N55 rwd e92(no secondaries, no resonator and we did pe mod on driver side). Exhaust came off with little fuss, we had to use some heat on the nuts at the downpipes from mild rust. I assumed that just pissed off the harness or it was just enough to make the sensor upset. None of the o2 were touched.

I had the same assumptions as you, not sure why but figured it was install related. Since I had planned on tuning and downpipes soon anyway, didnt consider it a big deal. But now.

[RSL]

OK, if the DPs came off for the install, it's more likely one was damaged. I was having a hard time figuring how they might've been if the stock DPs never came out of the car.

If AFRs are OK and trims are just skewed, it should be fine. There are safeties in place for failures, but I'd resolve any maintenance issues before adding a tune no matter what.

[type-dRew]

Originally Posted by RSL

OK, if the DPs came off for the install, it's more likely one was damaged. I was having a hard time figuring how they might've been if the stock DPs never came out of the car.

If AFRs are OK and trims are just skewed, it should be fine. There are safeties in place for failures, but I'd resolve any maintenance issues before adding a tune no matter what.

I dont know why i worded it like that. I have an Xi, we did not touch the stock downpipes whatsoever. I assume I was trying to type, the stock catback came off the downpipes with little issue, just needed some heat.

I logged my car, and aside from the codes being present, nothing looks different from the log I took before we did the install. So i'm not sure what if any impact the code or rear o2s themselves are having on the DME.

[RSL]

Originally Posted by type-dRew

I dont know why i worded it like that. I have an Xi, we did not touch the stock downpipes whatsoever. I assume I was trying to type, the stock catback came off the downpipes with little issue, just needed some heat.

I logged my car, and aside from the codes being present, nothing looks different from the log I took before we did the install. So i'm not sure what if any impact the code or rear o2s themselves are having on the DME.

I dont think the adaptations they do on the primaries is frequent at all. Might even be fixed mileage or run time intervals. It might not even perform them if there's a code set on a rear.

Definitely weird catback install triggered it or that it might've been damaged without directly touching it. I'd dig out INPA or something and see what the output voltage on that O2 is.

[spk]

e92 335xi stage 1+ vrsf 7 dci 102 Octan

Why so little boost ?

https://datazap.me/u/spk/log-1554225836?log=0&data=22
https://datazap.me/u/spk/log-1554225836?log=1&data=22
https://datazap.me/u/spk/log-1554225836?log=2

[335e92tx]

Originally Posted by spk

e92 335xi stage 1+ vrsf 7 dci 102 Octan

Why so little boost ?

https://datazap.me/u/spk/log-1554225836?log=0&data=22
https://datazap.me/u/spk/log-1554225836?log=1&data=22
https://datazap.me/u/spk/log-1554225836?log=2

its in bar bro.. thats a little hard for us .us to grasp. So, is this 14.7+ baro?

Im thinking you are pulling about ten percent more boost than ambient air... so 14.5x1.1 = ~ 15.8-16peak and about 15 tapered (above 5500). Looks good for the most part.

Try to normalize to psi for next log.. It will help my brain.. ;-)

[HeyTeeee]

https://datazap.me/u/heyteeee91/log-...og=0&data=4-19

Got a couple comments on a fb post hoping to dig deeper, thoughts? All stock no tune has vrsf charge pipe. One person said change gas which Ive been using costco. I read afr reading should jump to 234 which it doesn’t...maybe I didnt log correctly. What do you see?

[Shane303]

Can my log be reviewed please?

https://datazap.me/u/skampstra/mhd-e...24-25-26-27-28

[type-dRew]

Originally Posted by Shane303

Can my log be reviewed please?

https://datazap.me/u/skampstra/mhd-e...24-25-26-27-28

You should be logging timing corrections as well.

What's the setup? Any specific issues your having or chasing?

That's kind of an old map, i've heard the v5 maps were a bit 'hot'. Might want to consider stepping to a v7 or 8.

[Shane303]

Originally Posted by type-dRew

You should be logging timing corrections as well.

What's the setup? Any specific issues your having or chasing?

That's kind of an old map, i've heard the v5 maps were a bit 'hot'. Might want to consider stepping to a v7 or 8.

Timing on all cylinders is logged, "Raw timing".

[N54rsenal]

What are all the things we must be logging?

I reset my data logging options to default and added "oil temp/speed" looks like no one cares for LTFT1/2.

Just need to eliminate downshifting and do a couple 3rd gear pulls from 2000-7000rpm with TC off on a good road.

[Cm452]

I did not look at your logs, but, look at fueling and fuel trim. If it is lean and the ecu is trying to correct it with trims then I might suspect that the fuel pump is tired. Likewise if the mixture is lean you'll get knock and corresponding timing correction. And yes, if it maladapts it will run slower. If your boost can't be met because of hardware you'll see it in the wgdc. If your iats are over 40c/100f you'll apparently get boost reduction. You might get more help in the correct sub forum; this is for n54, not n55. Good luck!

[Cm452]

I took a clean 3rd gear pull to redline. Nothing stands out, but the car is slow. Why? I wanna tune it, but the thing is such a dog I'm concerned. It's textbook from what I can tell from my pi tuning days. Only thing weird is the throttle pull. Thanks!
https://datazap.me/u/cm452/3rd-gear-...=0&data=3-4-20

[type-dRew]

Opinions on this log?

Just tuned the car yesterday with mhd and xhp and it's been running great. Just like a second opinion,

https://datazap.me/u/typedrew/log-15...&data=3-21