Funky fuel trims? - Tuning Forum

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Funky fuel trims?
Wednesday, September 19, 2012 5:01 PM
Ok so im not much into tuning, don't have alotta knowledge on the efi side of things but im tryin to learn... I have been monitoring my car with the Torque app for a while now, its useful for checking codes and monitoring the motor and etc..

Vehicle info: 99 cavy z24, stock internal LD9, intake/exhaust, stock gm flash, 5 speed trans

I started looking at fuel trims, bank 1 sensor 1, constant back and forth -9 to +9 ish while driving around, seems normal enough for me? then bank 1 sensor 2 is pinned at like +99.2 at all times and I don't get why? is it something with torque not reading right or something on my car side?

My car does act weird sometimes, normal driving is always about the same, but then accelerating and 4th/5th gear highway pulls sometimes feel sluggish, and other times it just goes. As far as modifications its pretty stock on the fuel side, and intake/exhaust is just an ebay intake with k&n filter, pacesetter header and 2.5 exhaust.. oh and an adjustable fpr.. not that thats doing much.

And another thing, I am no longer getting codes for cat inefficency like I used to, I have one code for O2 heater circuit, but I used to get the cat code and a evap small leak code.. now they are just gone?

Any advice would help me out, i'm pretty busy right now since its harvest time here.. my nights and weekends are limited for the time being, so i want to try to gather as much info as i can now so I can hit it hard when I have time after harvest and fix anything I find.

Re: Funky fuel trims?
Friday, September 21, 2012 12:23 AM
You need a tune to get the ltft's back in line and replace your o2sensor other wise it will keep that code. I bet if you just just ltft histogram you might be out of an hr time wise and it would run alot better. or better yet a wideband you would be done real quick the first time.

see ya!

Re: Funky fuel trims?
Friday, September 21, 2012 5:56 AM
Actually, sounds like the sensor is not the problem, I would get a real scanner on it, this would typically sound like a leak in the exhaust around the converter.

On the upstream and downstream +/- 10% is normal, however something between there and the downstream is occuring unless its adaptive fuel control taking over (not likely on a stock tune)

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