Sale ends todayGet 30% off any course (excluding packages)
Ends in --- --- ---
Forum Posts
Courses
Blog
Tech Articles
What exactly does trim mean
What trim are you talking about - turbo or fuel? Fuel trim is percentage of fuel injectors duty cycle ECU changes in order to inject precise mass of fuel to meet the mass of air in order to achieve target Air/Fuel ratio. It can be short term, mid term and long term fuel trim- each one has it's own algorithm of calculating by ECU. Let's say your target AFR at idle is 14.7 and actual reading is 15. In order to get to 14.7 ECU will need to inject more fuel. So 15/14.7= 1.0204. ECU will be progressively adding fuel until AFR becomes 14.7 as targeted. It will require 2.04 percent more fuel injectors duty cycle (means fuel injector will stay open 2.04 percent more time) and your fuel trim will be +2.04 percent... It works the same from the other side- when your target AFR is 14.7 but actual AFR is 14.2 ECU need to deduct duty cycle in order to reduce the mass of fuel injected. 14.2/14.7-1= -0.034 so the fuel trim will be - 3.40 percent... You can get the idea from these examples.
Turbo trim is different - it is the ratio of compressor (or turbine) wheel inducer and exducer areas.
