Day Trip MPG malfunction

[Jrider]

So recently I noticed that the Trip MPG indicator is malfunctioning, it reads from 0-127 mpg up and down, all around. It never stays the way it used to. I understand that it will reach a high number and gradually go down, but this is all over the place. Has anyone else noticed this or had this problem?

The standard average MPG indicator is functioning normally.

I recently installed a Perrin CAI. Not sure if it was on the fritz prior to this.

[soulreapersteve]

Originally Posted by Jrider

So recently I noticed that the Trip MPG indicator is malfunctioning, it reads from 0-127 mpg up and down, all around. It never stays the way it used to. I understand that it will reach a high number and gradually go down, but this is all over the place. Has anyone else noticed this or had this problem?

The standard average MPG indicator is functioning normally.

I recently installed a Perrin CAI. Not sure if it was on the fritz prior to this.

Pretty sure thats normal. If its not, then mine has been malfunctioning since the day I bought it last year.

[Jrider]

I have had this car since august 2012, it would register up to high digits, but would fall off, but when it fell down the numbers would not shoot back up to 127 or anything close to that high. I wonder where it gets the info from to tell you the MPG.....

[humfrz]

Originally Posted by Jrider

So recently I noticed that the Trip MPG indicator is malfunctioning, it reads from 0-127 mpg up and down, all around. It never stays the way it used to. I understand that it will reach a high number and gradually go down, but this is all over the place. Has anyone else noticed this or had this problem?

The standard average MPG indicator is functioning normally.

I recently installed a Perrin CAI. Not sure if it was on the fritz prior to this.

Welcome to posting there, Jrider .......

Nope, haven't had that problem.

I doubt the installation of the CAI has anything to do with it.

Back in the day, I would suspect a bad connection (shorting out).

I'd suggest you start by checking the #17 fuse (under the dash - instrument panel).

Next, I'd check the #33 fuse in the fuse block under the hood.


humfrz

[swarb]

Originally Posted by Jrider

So recently I noticed that the Trip MPG indicator is malfunctioning, it reads from 0-127 mpg up and down, all around. It never stays the way it used to. I understand that it will reach a high number and gradually go down, but this is all over the place. Has anyone else noticed this or had this problem?

The standard average MPG indicator is functioning normally.

I recently installed a Perrin CAI. Not sure if it was on the fritz prior to this.

Read the manual.
There are two. One current, one average. You are probably on the current.

[Packofcrows]

^^^ LOL yeah...

[billwot]

Originally Posted by Jrider

So recently I noticed that the Trip MPG indicator is malfunctioning, it reads from 0-127 mpg up and down, all around. It never stays the way it used to. I understand that it will reach a high number and gradually go down, but this is all over the place. Has anyone else noticed this or had this problem?

The standard average MPG indicator is functioning normally.

I recently installed a Perrin CAI. Not sure if it was on the fritz prior to this.

What you're monitoring is the "real-time" MPG, so obviously it vary wildly depending on throttle position, gear, speed, etc, etc.

127 is the max of the display range. When you lift, the ECU shuts off fuel delivery, so the real-time MPG is actually infinity, but since our ECU doesn't display infinity, it defaults to max display value of 127.

[Jrider]

Thanks for the replies! I have read the manual many times. I think I will check the fuses as suggested. I mentioned that the average one is working fine. The current one I understand should move around. But even cruising at speed without letting off the gas it shifts around..... Not that it is a huge deal, just something I noticed.

[Jrider]

Originally Posted by humfrz

Welcome to posting there, Jrider .......

Nope, haven't had that problem.

I doubt the installation of the CAI has anything to do with it.

Back in the day, I would suspect a bad connection (shorting out).

I'd suggest you start by checking the #17 fuse (under the dash - instrument panel).

Next, I'd check the #33 fuse in the fuse block under the hood.


humfrz

Thank you for the welcome Humfrz. I have been checking this sight alot over the years, but just recently signed up. I always noticed that you have posted helpful information to the members here. Thank you for that.

[Tcoat]

Originally Posted by Jrider

Thanks for the replies! I have read the manual many times. I think I will check the fuses as suggested. I mentioned that the average one is working fine. The current one I understand should move around. But even cruising at speed without letting off the gas it shifts around..... Not that it is a huge deal, just something I noticed.

If the Average one is working right and not bouncing around then the Actual one is working right as well. They are simply two different readouts from the same data source and not on separate fuses or in any other way divided.
The real time actual one will move even at a constant speed unless you are on perfectly level ground. The car is always making small adjustments in fuel flow to maintain the speed you are holding. The Actual gauge will even move (sometimes by a lot) even if you are on cruise control. I have never really figured out the value of even knowing what your current use is anyway since it can change by the second.
Not sure what could possibly have changed if you think it is different now than it used to be though.

[Jrider]

You know. After further thought, I believe you are right. I think after installing the Perrin CAI my mind was assuming that something would not work right or would malfunction. I must have forgotten seeing the meter bounce all over the place. I still don't remember it going up to 127, but oh well. Thanks for setting my worried mind straight.

[billwot]

Originally Posted by Jrider

You know. After further thought, I believe you are right. I think after installing the Perrin CAI my mind was assuming that something would not work right or would malfunction. I must have forgotten seeing the meter bounce all over the place. I still don't remember it going up to 127, but oh well. Thanks for setting my worried mind straight.

I guarantee you that when you lift, the real-time fuel monitor will display 127, the max value stored in the ECU.