can I manually change fuel trim rich/lean ?
06-24-2015, 09:58 PM
#1
Member
Thread Starter
Join Date: Nov 2007
Location: ontario, Canada
Posts: 171
Likes: 0
Received 1 Like
on
1 Post
C230 COUPE 2003 M271
can I manually change fuel trim rich/lean ?
got a check engine light and hooked up my scan tool. it says p0170 fuel trim out of spec. I see the long term fuel trim is showing +10% or so. I am also getting terrible fuel economy so it makes me think it thinks it needs to add more fuel but it is actually dumping fuel right through to the tail pipe. Is there a way to manually change the trim and see if the economy gets better? until I find what is causing the problem in the first place.
06-25-2015, 11:42 AM
#3
MBWorld Fanatic!
Large deviations in fuel trim values are likely due to a problem. Finding and correcting the culprit is the way to go rather than messing with fuel trim values manually, even if you find a way to do it.
06-25-2015, 11:53 AM
#4
MBWorld Fanatic!
Positive fuel trims are usually an air leak or low fuel pressure, get the car checked. Fuel trims are there to keep the engine running right for emissions reasons, not to adjust so you don't have to fix your car.
