Heyyy
I was wondering if there is a manual that says what ranges are good and bad for these scan tools. I bought one from harbor freight because I had a check engine light on and needed it for my inspection. I want to see how my car is like the scans you do, but I don't know what the numbers mean. Short term fuel long term fuel etc. I was looking to see if there's something that gives a range like if you got blood work done( vit d should be this range LdL that range hdl this range etc)
You'd be better off learning what the numbers mean than what they should be.
Take fuel trims for example. If you understand STFT and LTFT and how and why the computer adjusts those numbers, you'll see how they can be useful to help you diagnose engine problems.
Start with the basics. Here's an older video on fuel trims. You can tell because the $100 (cheap) scanners he's referring to in the video only cost about $40 today.
After you watch it, you'll not only know what those STFT and LTFT numbers should be, you'll have an idea of how the computer uses voltage values from other sensors to calculate those fuel trims. (which can help you when trying to diagnose a problem)
Here's Part 1 and Part 2
https://www.youtube.com/watch?v=5WnM_NsOtd8&t=0s
https://www.youtube.com/watch?v=cARQ0jZZ4Qc
Watched that video a few months ago VERY Enlightening
You mean like this:
Bad
-------------------
Okay
------------------
Bad
?
Scan tools in general do not give this simple of a graph. You need to know the numbers for your car because it for sure does have a range it should be between. But it's different for every car. Some might show red for bad or green for good like blue drivers. You can Google what numbers are good for your vehicle.
In general though between positive 10%, and negative 10% when the engine is running at a steady speed for short term fuel for example.
The best way to learn is from experience and playing with them. Find friends with brand new cars and ask if you can use your scan tool to see how their car is running. Then find others that are older and might be worn a bit. The LTFT should be close to zero on a well running engine, and STFT should alternate a small amount positive and negative. Positive means the mixture is lean (more air than fuel) negative means it's rich (more fuel than air). STFT alternates +/- within a couple percent to keep the catalytic converter happy, the LTFT is a running average of the adjustments the computer makes to the mixture, it should be close to 0. Analyzing this data yourself will reveal an issue. Codes are a pointer, but they're not always the problem. It takes years and years to get as good as Scotty. Newer cars have more livestream data, older have less. My '99 Ranger has around 19 pieces of live data my Innova 3100 can read, but my 2017 Mustang has over 50.
Thank you for all the advice. I do have a older vehicle its a 2004 Santa fe. Runs like a top get oil changes every 3,000- 3,500 miles. I have had it for 7 years, and put many miles on it as it is my daily driver. Is it needed that I know what the numbers mean no. But no one I know family or friends has a scan tool and it's cool to have one. I can help others out with check engine lights, battery/ alternator check etc. But if they asked me to run live data I wouldn't know what the numbers mean. The scan tool I have only has the numbers black. That's why I'm wondering if there's ranges for all the numbers not just STFT and LTFT. I do have a mechanic, that has a 5,000 dollar scan tool I could maybe ask to fully scan my car. I just wanna have confidence in what I'm reading, incase others want me to scan their car instead of going to autozone/ advanced auto.