Obdii "live data" ???

DC1263 · #1 03-25-2009, 07:30 AM

Recently lost some fuel mileage, not sure why?

Gone from 28 mpg's to 25 mpg's

Maybe just the colder weather?

No CEL, 3130 Scanner, Green Light, No codes...

Lots of "LIVE DATA" though,,, What does it all mean ???

I imagine these parameters must fall within a particular range ?

Not much good if I can't interpret the data.

The definitions are all out there...

STFT = Short Term Fuel Trim

B1 = Bank 1

S1 = Sensor 1

IAT, ECT, O2, MAF, MAP, HDORWM... And so on...

Again...Lots of "LIVE DATA",,, What does it all mean ???

Where can I find info to help me understand this data ?

Also pushin' 110,000 mi

I've read around where the Oxygen sensors should be replaced @ anywhere from 60 -100,000 mi ???

richtazz · #2 03-25-2009, 07:42 AM

A factory repair manual would have the acceptable ranges for all the data you're seeing. I don't know of a free website that offers that information.

DC1263 · #3 03-25-2009, 08:22 AM

Thanks Richdude,

Figured that!

With as much info that is available for free, not everything is free !!!

Guess I'll save up the Buck50 for the FSM. Be good to have.

Whats your take on replacing the O2 Sensors ???

I've read where even thought they function within specs, they do become dirty, so there would be benefit from replacement ???

Thanks Again...

richtazz · #4 03-25-2009, 08:56 AM

Oxygen sensor replacement is a dicey issue. I believe that the factory replacement interval is rediculously low mileage. Oxygen sensors will last a lot longer in a car with mostly highway miles versus one used for short trips. A sudden drop in mileage like you're experiencing with no CEL may be caused by a carboned up O2, but it will normally show up as short and long term fuel trim readings being off.

DC1263 · #5 03-25-2009, 09:13 AM

90% Highway, 10% 'Roundtown

My drive to work is 110 miles round trip daily 5 days a week, mileage does add up quickly.

Car runs / drives "GREAT" otherwise.

Thanks Again For Your Input

NOVAZ27 · #6 03-25-2009, 02:56 PM

Fuel mileage usually goes down in the winter time since the Big Oil folks make a winter blend that is Lighter in nature. This helps the gas to atomize/vaporize easier on cold winter days. Being lighter usually means a drop in mileage.

HOPE THIS HELPS

doctorhrdware · #7 03-26-2009, 12:35 AM

My winter mileage drops from about 30MPG down to around 26MPG.

DC1263 · #8 03-26-2009, 09:43 AM

Now you'all got me thinkin', maybe it is the "Fuel Blend", Up until recently I would use Shell Gasoline almost exclusively, only because it was convenient on my drive to work route, but a while back they opened a new stretch of highway that takes me out a different way, So lately I've been mixing it up with Shell, BP, Murphy's USA and Exxon, Maybe I'll go back to one blend and see if my mileage comes back... before I make any other changes

BNaylor · #9 03-26-2009, 09:59 AM

Post the short and long term fuel trim values and we can explain it to you or it might indicate why your fuel economy has dropped.

When a 02 sensor gets really bad or lazy it normally sets a code DTC(s) in the form of lean to rich or rich to lean.

Try staying with one brand of gasoline and do not blend them. What grade or octane are you using?

DC1263 · #10 03-26-2009, 10:17 AM

I'll take it for a ride later and post the STFT / LTFT later on this afternoon, but from memory they fluctuate anywhere from + - 7 or so, I don't recall anything higher or lower than that but I haven't had the scanner very long and I will need to give it back to its owner soon, So I'm going invest in my own in the near future, definitely a good tool to have handy.

02 S1 : bounces around between 0v and .950v
02 S2 : stays around + - .600v or so

Bought it with 28,000 and I've always used "87"

BNaylor · #11 03-26-2009, 10:34 AM

Quote:

Originally Posted by DC1263

02 S1 : bounces around between 0v and .950v

Bought it with 28,000 and I've always used "87"

OK so this is a base model with the NA SIII 3800 engine. The pre CAT 02 sensor appears to be working properly or not dead based on your data. Typical readings will be in a range of 0-999 mV (millivolts) and it should fluctuate.

DC1263 · #12 03-26-2009, 07:23 PM

6 frames of live data I captured earlier, Nothing stands out as obvious to me, the software that comes with the 3130 is kind of lame though can't do anything with it, graphing is sort of lame too, but anyway,Anyting jump out at you ???

I appreciate your input... Thanks Again !

troy1 · #13 03-26-2009, 08:47 PM

Hey DC1263 do you have Microsoft office? I've got a wonderful list all data and definitions and "generic" parameters for most GM cars and trucks

doctorhrdware · #14 03-26-2009, 09:57 PM

He could use open office which is freeware and a Microsoft office compatible.

DC1263 · #15 03-27-2009, 07:21 AM

Troy,

Yes, I do have MS Office, anything you could send my way would be greatly appreciated, It would be real nice if I could dump this data into an excel spreadsheet, but as I said earlier, the scanner software is really kind of lame, I think they could have done better with it, anyway, I could load it all in manually though, no big deal, sometimes it's easier to visualize whats happening when this kind of data graphed rather than trying to follow a bunch of fluctuating numbers

Thanks, you guys are a great help !!!

POST REPLY TO THIS THREAD