parad1mg Posted December 15, 2015 Share Posted December 15, 2015 Hello all, Recently my MPG needle gauge have been behaving rather erratically. It would go all the way to the minus sign while cruising at highway speeds or would bounce around from minus to middle to plus. Is there a sensor that this gauge is tied to that can be replaced? My MPG readout on the little screen remains quite consistent and reasonable (15-16 MPG, I am on a rich/safe/poop tune until I get a new turbo) but the needle goes wild sometimes. I do get the occasional P0172 Rich, Bank 1 code and a few afterfires that scares the crap out of pedestrians, but i think that's all because of the improper tune due to my bad luck with a BNR turbo. Thoughts? Thanks!!!! Link to comment Share on other sites More sharing options...
solidxsnake Posted December 15, 2015 Share Posted December 15, 2015 Have you just cleared your trip meter? The MPG gauge shows you how it's affecting your average MPG, regardless of the instantaneous. For instance, if my average is at 23MPG and my instantaneous is 23MPG, it'll be dead-center. If I'm instantaneously using 24MPG, it'll be on the (+) side. When you clear your trip meter, a couple MPG more-or-less than your average will cause a much greater change in your average versus having many miles on your trip meter. Just a thought. Link to comment Share on other sites More sharing options...
parad1mg Posted December 16, 2015 Author Share Posted December 16, 2015 Have you just cleared your trip meter? No, I did not. The MPG needle gauge is directly affected by my throttle input. It sort of acts like a vacuum gauge. To give you an idea of what my gauge does; when going downhill with no throttle input and load, the needle would sometimes go all the way to the minus sign and back to the plus side and bounce back and forth. At 3/4 to full throttle from a dead stop, the needle would sometimes stay at the high plus side. to clarify which gauge I'm talking about, it is the one right below the speedometer in this picture: http://www.cars101.com/subaru/outback/Ob08XTinst1.JPG Link to comment Share on other sites More sharing options...
Grothe08LGT Posted December 16, 2015 Share Posted December 16, 2015 First.. Why the f**k is your gas that low.. Second, I'm not sure to your mpg needle issue sorry Link to comment Share on other sites More sharing options...
solidxsnake Posted December 16, 2015 Share Posted December 16, 2015 First.. Why the f**k is your gas that low.. Second, I'm not sure to your mpg needle issue sorry Such help. Many assistance. :spin: OP, from a check in the service manual, the troubleshooting steps say it's either a cluster problem, or a communication problem... personally I think it's neither, though. I know many other cars, the MPG gauge is actually a vacuum-driven gauge... I don't think it's entirely true on the Legacy, since it keeps track of your average MPG as well (which the gauge cluster/ECU stores), but sensors related to that might be worth looking into. Could potentially be messing with your fueling as well, which could be linked to your MIL. Link to comment Share on other sites More sharing options...
Phate Posted December 16, 2015 Share Posted December 16, 2015 Pretty sure it's just a vacuum gauge. If the digital readout (both instant and average) is working fine, it sounds like an issue with the cluster. Do you have an accessport or any other means of datalogging? You could log manifold pressure, throttle position, and afr to get an idea of if things are actually happening while the gauge is freaking out, or if it's just the gauge. Link to comment Share on other sites More sharing options...
solidxsnake Posted December 16, 2015 Share Posted December 16, 2015 Pretty sure it's just a vacuum gauge. If the digital readout (both instant and average) is working fine, it sounds like an issue with the cluster. Do you have an accessport or any other means of datalogging? You could log manifold pressure, throttle position, and afr to get an idea of if things are actually happening while the gauge is freaking out, or if it's just the gauge. I would think so too, but I'm fairly certain there's nothing but electrical connections to the cluster, which I believe all run to the ECU (and not to any individual sensors). I also know that the gauge acts according to your current avg MPG as I described above, which means it can't just be a simple vacuum gauge. Link to comment Share on other sites More sharing options...
parad1mg Posted December 17, 2015 Author Share Posted December 17, 2015 First.. Why the f**k is your gas that low.. Relax kiddo, it's a just picture off of google images. Such help. Many assistance. :spin: OP, from a check in the service manual, the troubleshooting steps say it's either a cluster problem, or a communication problem... personally I think it's neither, though. I know many other cars, the MPG gauge is actually a vacuum-driven gauge... I don't think it's entirely true on the Legacy, since it keeps track of your average MPG as well (which the gauge cluster/ECU stores), but sensors related to that might be worth looking into. Could potentially be messing with your fueling as well, which could be linked to your MIL. It seems this issue has been brought up before but never resolved: http://legacygt.com/forums/showthread.php/mpg-needle-swinging-229941.html It does act like a vacuum gauge but i think it is tied with the cluster controller: http://legacygt.com/forums/showthread.php/change-mpg-gauge-into-boost-gauge-180038.html My major concern is the sensors it is reading from and not the accuracy of the MPG meter. Those same sensors might be used for other parts and may have been affecting other components on the vehicle. Link to comment Share on other sites More sharing options...
parad1mg Posted December 17, 2015 Author Share Posted December 17, 2015 I would think so too, but I'm fairly certain there's nothing but electrical connections to the cluster, which I believe all run to the ECU (and not to any individual sensors). I also know that the gauge acts according to your current avg MPG as I described above, which means it can't just be a simple vacuum gauge. I do have an V3 AP but i really can't rely on the reading since i'm on a watered down stage 3 tune. Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.