E90Post
 


TireRack
 
BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Powertrain and Drivetrain Discussions > N54 Turbo Engine / Drivetrain / Exhaust Modifications - 335i > Ltft and Stft different on each bank



Reply
 
Thread Tools Search this Thread
      07-23-2016, 03:53 AM   #1
Theador
Lieutenant
30
Rep
444
Posts

Drives: BMW E91 M Sport 335i
Join Date: Nov 2013
Location: Henley on Thames

iTrader: (0)

Ltft and Stft different on each bank

I've been monitoring my fuel trims which are generally hovering around 0 now or going into negative, however my bank1 side is always 2-3% lower than bank 2. Surely they should both be the same?
__________________
e91 335i MSPort 6MT | MHD Stage (whatever it is this week) | VRSF Catless DPs | Hartge ARBs | Quaife LSD | Eibach Springs | 313 Alloys | VRSF 7" Intercooler and Ingen Intake

Appreciate 0
      07-23-2016, 06:55 PM   #2
ferocity02
Lieutenant Colonel
United_States
167
Rep
1,556
Posts

Drives: 2007 E90 335i
Join Date: May 2014
Location: USA

iTrader: (7)

Ideally they would be the same, but the injectors aren't perfect. A couple percent difference is pretty reasonable.
Appreciate 1
      07-24-2016, 05:44 AM   #3
titium
Lieutenant
35
Rep
417
Posts

Drives: 2009 BMW 135i
Join Date: Jun 2015
Location: Sydney

iTrader: (0)

all the same index? if new ones were installed were they coded?

I honestly wouldnt worry until they start getting into double digits. couple of % is pretty normal.

in an ideal world the fuel trims would be 0 all the time. fuel trims are there to compensate for non perfect parts of the system, errors in intake air quantity measurement, injectors and injector aging, unequal airflow distribution between cylinders, fuel quality ect ect. of which all of these are perfectly normal.
Appreciate 1
      07-24-2016, 11:21 AM   #4
135Pats
Major General
135Pats's Avatar
United_States
250
Rep
6,399
Posts

Drives: A few BMWs
Join Date: May 2012
Location: Maryland

iTrader: (3)

I wouldn't get too hung up over a delta like that between banks. If one was pegging STFTs and another was pulling fuel, then sure you'd have an issue to track down. This to me is more a reflection of the injectors not being literally 100% identical.

You are fine.
__________________
E88 N54 Alpinweiss/Coral Red/Motiv HTA 3586r Tial .82AR/Other stuff...652WHP

F30 N55 XDrive EBII
Appreciate 1
      07-24-2016, 12:41 PM   #5
Theador
Lieutenant
30
Rep
444
Posts

Drives: BMW E91 M Sport 335i
Join Date: Nov 2013
Location: Henley on Thames

iTrader: (0)

Thanks guys.
Appreciate 0
      07-24-2016, 01:43 PM   #6
ferocity02
Lieutenant Colonel
United_States
167
Rep
1,556
Posts

Drives: 2007 E90 335i
Join Date: May 2014
Location: USA

iTrader: (7)

Just to add more to this thread, the LTFT difference between banks can indicate a potential issue. For example, when my #6 injector was leaking, my bank 2 LTFT was typically 15-25% lower than bank 1 under idle and normal cruising conditions.

A difference of a couple percent is normal. After replacing all injectors I'm still seeing differences of 1-3%.
__________________
2007 E90 335i Pre-LCI
Appreciate 2
Reply

Bookmarks

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -4. The time now is 10:09 AM.




e90post
e90post
Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2016, Jelsoft Enterprises Ltd.
1Addicts.com, BIMMERPOST.com, E90Post.com, F30Post.com, M3Post.com, ZPost.com, 5Post.com, 6Post.com, 7Post.com, XBimmers.com logo and trademark are properties of BIMMERPOST