Negative LTFT
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Member
Joined: May 2016
Posts: 130
Likes: 37
From: Oxford, UK
GLC63S, A35 AMG
Negative LTFT
Any clues as to what would be causing the long term fuel trims on both banks to be running at between -6 and -9 most of the time? the short term trims fluctuate between +1.8 and -2. This is with the car idling, and readings through torque.
No apparent performance issues. No fault codes. It's a 2012 C63.
Thoughts? Or just one of those things?
No apparent performance issues. No fault codes. It's a 2012 C63.
Thoughts? Or just one of those things?
Last edited by Wiggis; Jun 7, 2017 at 04:46 PM.
MBWorld Fanatic!
Joined: Feb 2011
Posts: 1,752
Likes: 175
From: London, UK
W212 - E63 AMG
I want to say perhaps give your maf a clean with carb cleaner and check over your air filters to ensure they're not badly clogged, but then your car isn't exactly old either. Could even be the sensors themselves. I'm not sure, so hopefully somebody will be along shortly. I am pretty sure though that a dirty or tired maf can cause a negative fuel trim.
MBWorld Fanatic!
Joined: Sep 2016
Posts: 1,175
Likes: 130
From: NY
2010 C63 2019 GLA45
These are not very bad numbers. Drive it and see what the numbers do. They may change from cold to warmed up.
With my car, they were smallest when cold and by the time I got to work, they increased by 4-5 points.
With my car, they were smallest when cold and by the time I got to work, they increased by 4-5 points.
