Help me read fuel trim %
TECH Fanatic
Joined: Jun 2007
Posts: 1,316
Likes: 3
From: Dolla$ , TX
No offense op but have you read through our replies and tried to understand what the graphs mean? Instead of just posting snapshots and asking for evaluation? We explained it pretty thoroughly.
Takinga snapshot doesn't really do much as the change so frequently. You need to understand what is acceptable and what's not per the posts above then interpret your results. Also the idle trims don't mean much you have to see them under load while crusing at speed
Takinga snapshot doesn't really do much as the change so frequently. You need to understand what is acceptable and what's not per the posts above then interpret your results. Also the idle trims don't mean much you have to see them under load while crusing at speed
sorry i should have been more clear. I dont normally pay all that much attention to stft's at idle because little hiccups happen and they can skew one way for a sec or two. not enough to skew the ltft's but it does happen. the way the op is taking snapshots that could easily capture bad data.
ltft's are important like you said to capture vac leaks or other things, they should be around 0 at idle
ltft's are important like you said to capture vac leaks or other things, they should be around 0 at idle
The reason I posted more readouts was because someone asked me to post what they were at idle. So I did. I'm going to replace O2's and recheck all of them after that. I think my bad mpg's was mainly because of my new job in town. I only got 110 miles out of like 14 gals of gas which equals about 8 mpg. I just didn't think that was normal or possible for a bolt on LS1. But I have been driving pretty ridiculous lately, so I guess it's possible.
LTFTs will always adjust to try and keep the STFTs near 0. The exception is if the LTFTs have maxed out at + or - 25% and that is still not enough to keep drive the STFTs to near 0 then you will see STFTs farther away from 0.
You should want to see your B1 sensor switching as good as your B2 sensor. B1 is looking a little lazy for whatever reason.
You should want to see your B1 sensor switching as good as your B2 sensor. B1 is looking a little lazy for whatever reason.
Well I figured out that it wasn't normal for my car to get to 233 degrees. The thermostat wasn't working. Now it sits at about 200 degrees at idle, so at least I got one thing figured out. Still waiting on my other O2 sensor that I ordered offline. After waiting this long to receive it I wish I would of just bought them from autozone for twice the price 
Teching In
Joined: Sep 2013
Posts: 43
Likes: 0
From: Straya
The trims look ok to me. The B1 sensor looks a little lazy at idle but comes good at higher rpm. Any chance you have an exhaust leak on that side? I don't think it's bad enough to be killing your economy though.
5 minute drives will kill your economy because engines use a lot more fuel when cold. Not sure how you drive but you'll get best economy cruising around town at 1500 rpm and shifting at ~2500 when accerating gently; people sometimes reason that higher rpm uses less fuel because there's less load on the engine but it's actually the other way around (within reason, don't lug it to the point it grumbles and struggles). Take a good highway cruise and see if your economy comes good again.
Oh to live 5 min from work - I'd be jumping on the pushbike and saving the car for the weekends!
5 minute drives will kill your economy because engines use a lot more fuel when cold. Not sure how you drive but you'll get best economy cruising around town at 1500 rpm and shifting at ~2500 when accerating gently; people sometimes reason that higher rpm uses less fuel because there's less load on the engine but it's actually the other way around (within reason, don't lug it to the point it grumbles and struggles). Take a good highway cruise and see if your economy comes good again.
Oh to live 5 min from work - I'd be jumping on the pushbike and saving the car for the weekends!
