MPGuino reading MPG backwards? Helpsky?
 

Decided to make a new thread for easier searching and to clutter up the release one thread a little less.

Anyway, got everything hooked up, but the MID seems to be reading the MPG in an inverted way. When I'm sitting still I get 99.9 MPG and when I'm moving during DFCO (there, I said it!) I get 0.00 MPG. Just cruising gets me like 2 MPG, :)

Ideas?

Thanks

I suggest you floor it in first gear at all times for optimal efficiency. Your guage told you so. Just belive it.

I actually tried that to confirm my idea and it worked, :p

Get your mph dialed in first, the first screen, upper right should be instantaneous MPH. If that is messed, then there is little hope for the rest. If it responds to the throttle pedal and not the vehicle speed, then you have your signals crossed, etc. etc.

The wires weren't switched.

The Speed display was showing horribly wonky unconsistent numbers at the same speed and the distance we very underestimated. Should I just go for a drive and compare the distances and change a value? If so, which value? Is it linear?

Is the mph figure consistently low or high by a certain percentage? Or is it completely random? If it is off by a percentage then what would that percentage be? You should probably be using 8204 for the vsspulses per mile for an asian car. Can you share which specific vehicle this is going in? Any other helpful bits of info?

I had the same problem with the SuperMID kit, never got it ironed out.

I suspect it was because I had the vss and inj wires switched. Double-check them Ben!

Triple-check them!

Do it now!


But yeah, make sure you don't have anything too whacky for vss/mileage parameter. The 8204 is pretty much spot-on if you're running stock diameter tires.

I just test drove again. Looking at the IM/S:CM/D screen is seems that S is showing the injector pulse as speed.

However, when I switched the wires the speedo died and would only blip under heavy acceleration (heavy fuel use), so I'm kind of confused...I might have switched the wrong vss wire!!! That just occurred to me, I'm stupid...I'll switch them back and do it again...

This is a 91 crx, but with a vx engine, some random vss, and integra gauge cluster...I'll switch them again in the morning and see what I'm doing wrong...

Andrew, you're right I think, I just needed moar extra triple checking on the wirezzz, will do it in the morning when it's not dark out.

What car is it, which VSS wire on the ECU did you use and what color was it?

91 crx, b10, it's not the stock color because I repinned most of my ecu plug wires.

I'm concerned about your car speedo getting conked out, something does not sound wired right at all. It does not seem likely that a speedometer circuit should notice a 100k resistor tapped into it.

It conked out because I accidently wired the injector signal to the speedo. There are two identical looking wires from b10 to the speedo area, one to the mpguino, another to the speedo. I switched the injector signal with the speedo one, not the mpguino one. No worries.

I'm wondering if your injector circuit is high-active (not low-active like the rest of us)...