Z06Samuel

Hello, I was wondering if any of the auto code scanners pick up the fuel trim? I stumbled over the subject of fuel trim and thought it would be a great way to check on the car for any intake leaks that don't register codes.
Thank you,
Sam

tennblkc6

don't think a code reader will have this function. you can put a under the hood vacuum gauge on it to achieve your goal.

C6z06man

Yeah you will need a scanner with live data. A code reader only reads stored codes. Do you think you have vacuum leaks?

tblu92

There are several things that can cause either negative or positive fuel trims---The short term fuel trims as a tuner are of no concern---It's the long term ones that can indicate some issues--but they can vary---
A vacuum leak would cause both sides to go way positive
as long as it is POST MAF---a pre MAF air intake leak would simply just let un filtered air into your engine
If you have a medium difference between left and right sides that can simply indicate a small exhaust leak--
A major split between right and left can be a big exhaust leak or a failing front 02---
A dirty or clogged air filter would make the LTFT's go way negative on both sides
A fouled or oil saturated MAF from an oiled CAI could cause the LTFT's simply to go crazy and go either way
Normally to get a rich/lean code means that the LTFT's have gone beyond apprx 20% which is HUGE---
Most handheld scanners will read live 02 voltages and live LTFT's

muncie21

My Aeroforce scan gauge provides both LTFTs and STFTs. Fits in a pillar mounted gauge pod

Twistedpixels

if you dont want to buy a tuning device then grab a Datalogic device and you can configure it to read fuel trims along with any other PID you want. Plus you do not have to install a gauge in the car it reads out on the HUD.

Dan_the_C5_Man

This is the answer..