weird MPG gauge issue (post S52 swap)

[snuggz]

So,

When I did my swap, I printed out the guide to get the MPG gauge working (yes, I know it's worthless -- just bear with me here), and to my surprise, Pin 24 was already filled and had continuity with X16 up by the cluster. "Cool", I thought, one less thing to do.

But after finishing, I realized something was amiss -- at stoplights and such, the gauge shows 0mpg (correctly) but as soon as I start moving, it just swings right past 40mpg (burying the needle) and stays there. Obviously, it's getting more/less voltage than it should be... anyone ever experience this? I just left it alone for the last year, as I had a bunch of other stuff to sort out, but it's really starting to bug me, and I'm not exactly where to turn next...

Oh yeah, anyone know if it's possible to get the OBC to read this stuff correctly? Maybe a 323Ti OBC swap?

[campaiar]

Snuggz that's exactly what my mpg gauge did post my S52 install. Once I hooked up the wire per the instructions it started to function properly.

The wire is for fuel usage. Without it, its just measuring speed against zero fuel usage.

You might need to take another look at it.

No OBC on mine so I can't help you there.

[snuggz]

...buuut there appears to be continuity between Pin24 under the hood and P21 on the X16 behind the cluster already. What did you change (if this is the case anyway)? I was under the impression it's only the one wire... but there's a large possibility that I'm just a dumbass...

[campaiar]

Hahaha.. Well I'll let that go.

I know on my 1998, I had to add the wire and I did exactly as shown in the write up and it works fine. Not sure why you would have the wire already installed when the rest of us don't.

Just retrace your steps again and see if you missed anything.

Electronic gremlins suck.

[Bluebimma]

Originally Posted by snuggz

So,

When I did my swap, I printed out the guide to get the MPG gauge working (yes, I know it's worthless -- just bear with me here), and to my surprise, Pin 24 was already filled and had continuity with X16 up by the cluster. "Cool", I thought, one less thing to do.

But after finishing, I realized something was amiss -- at stoplights and such, the gauge shows 0mpg (correctly) but as soon as I start moving, it just swings right past 40mpg (burying the needle) and stays there. Obviously, it's getting more/less voltage than it should be... anyone ever experience this? I just left it alone for the last year, as I had a bunch of other stuff to sort out, but it's really starting to bug me, and I'm not exactly where to turn next...

Oh yeah, anyone know if it's possible to get the OBC to read this stuff correctly? Maybe a 323Ti OBC swap?

Ive actually been working on getting the stock 2-button OBC to read the info for MPG and Miles til Empty but im not sure if the OBC can read the info and display it on the screen or if only the cluster can read the info and move the needle accordingly. Im trying to figure out what the non-ti OBC uses to display its MPG and Miles til Empty, im pretty sure our obc would be able to display the correct miles and such. My current obc reads 6mpg no matter what and the miles til empty, even on a full tank, reads about 125 or so miles.

[snuggz]

Originally Posted by Bluebimma

Ive actually been working on getting the stock 2-button OBC to read the info for MPG and Miles til Empty but im not sure if the OBC can read the info and display it on the screen or if only the cluster can read the info and move the needle accordingly. Im trying to figure out what the non-ti OBC uses to display its MPG and Miles til Empty, im pretty sure our obc would be able to display the correct miles and such. My current obc reads 6mpg no matter what and the miles til empty, even on a full tank, reads about 125 or so miles.

Wow... that is like the opposite of what mine shows. Mine reads really high for MPG's (around 45mpg all the time) and calculates the range on that, so it's always much more optimistic than real life... (I really wish it was actually getting 45mpg ... that would be sweet...)

I guess I'll just rip the cluster out again and re-check everything... I need to re-laminate the tach anyway.

Are you still OBD-II?

[campaiar]

My OBC did the same thing after the 325 swap. The Miles Till Empty read high as well, but zero still meant zero which was nice.

[Bluebimma]

Originally Posted by snuggz

Wow... that is like the opposite of what mine shows. Mine reads really high for MPG's (around 45mpg all the time) and calculates the range on that, so it's always much more optimistic than real life... (I really wish it was actually getting 45mpg ... that would be sweet...)

I guess I'll just rip the cluster out again and re-check everything... I need to re-laminate the tach anyway.

Are you still OBD-II?

Nope, im OBDI now.