MPGuino 1991 AUTOMATIC

[robertwb70]

I can't find anything about hooking this to an Auto trans car (1991 geo metro 1.0), I'm quite sure I have the pos, grnd and injector connections correct but the VSS is different than the manual cars. My car has a separate VSS in the transmission with 2 wires going to it I tried both of them and the first one didn't seem to do anything and the second one did once the speed was brought up (on jack stands for testing).

I know my speedometer is off due to the 13" tire/wheel upgrade (I calculated 8.3333% difference). I adjusted the VSS pulses per mile to 7524 from 8208 but now that I think about it this probably isn't right but I didn't want to start with a value that I know is wrong.

How much of an adjustment does this parameter take for a change like I have?

I didn't see (on the wiki or here) a way to get the MPGuino to display the VSS pulse count either or I could use that? if this is possible how is it done?

I get no instantaneous MPG reading until I get up to about 40MPH and then if I accelerate long enough the reading drops until it gets all the way down to zero and stays there until I lift completely off the accelerator-then it pops back up to 999- any ideas why it would do this? (I know 999 means coasting in gear already)

[dcb]

Dunno if this thread will help or not with the vss. But you want the one in the speedo, not the one from the trans I think (different signal strengths).
http://ecomodder.com/forum/showthrea...tml#post108671

^89 metro w/auto

[robertwb70]

OK I found the yellow/green wire under the dash on the drivers side above the fuse block ( the ECU is right there too). That made everything work much better and I was able to get a rough speed calibration for my car of 8100 pulses ( I went 50 MPH on the speedo and tried to get MPGuino to indicate 54.16 for the 8.333% difference) close enough for now.

It did freeze up on me once and there is one part on the back that I noticed gets a little warm is this normal or might I still have some connection problem?

So, from here, if I understand this right, once I get actual mileage from the next tank I start adjusting the injector input until I can get actual and MPGuino mileage to match right?

[dcb]

Here is the calibration page, it should spell it out, might want to be sure all connections are solid first and I would just leave it on the custom screen while driving to reduce the possibility of freeze in mid calibration.

Mpguino calibration - EcoModder

[robertwb70]

Thanks, don't know how I missed that page with all the time I've been looking at stuff for this- that's just what I was looking for.

[dcb]

good deal

[robertwb70]

The unit was working good today but it froze about 5 miles from home.

What causes it to freeze and is there a way to stop it from happening?

What is the best course of action to get it working again without wiping out the memory?

There is a part (op-amp I think?) in the picture below that gets too hot to touch for more than 1 second- is this normal or a sign of a problem?

[dcb]

that is the voltage regulator, it can get warm. I don't have a pat answer on the freezing, can you describe the conditions when it happened?

I would turn the brightness down (with the middle button) to like 1, and that should keep the regulator happier anyway.

[robertwb70]

I keep the brightness set at one already.

Today it happened (I think) right after I hit a good size bump in the road in a construction zone (the 40 psi in the tires makes bumps feel a little worse than they really are).

So disconnect/ reconnect the power the only way to get it going again?

[robertwb70]

I finally got around to the last resort yesterday - hooking the unit directly to the battery, and it looks like that has solved all the issues I was having. It has worked 2 days now and about 65 miles which is a new record for me.

It was so bad last week I just unplugged it for about 4 days because it would freeze and/or reset itself almost continuously...I was starting to think something was wrong with it.