ECU doesn't match chassis

[fixkick]

First off you Odometer will not show correct miles with huge tries, IT CAN NOT.
that means MPG is impossible to do , unless donen with GPS logs. OK?
80mph in 2door is crazy Idea on this 2000 lb box kite. wildly dangerous for sure in any crosswind or worse buffeting winds, and 10x on any bridge.
80 is 84on this car wrong tires, wow.
end rant
LIMPHOME = FAILSAFE = limp mode, etc.
The engine ECU is in limphome?, is the CEL lamp glowing at key on? then turns out? running.
if stays on that is limphome and 15mpg is what it does like that.
and is not running good. sure it runs but is only burning 1/2 the fuel the rest goes to the atmosphere (smog)
with big tires, the prop drive shafts turn slower, and speedo reads slower. and that causes miles to be way shorter that REALITY. (gear ratio facts)
the error is about 5% my guess,. if I knew your tire circumference i can compute true error.
http://www.fixkick.com/part-time-test.html#SPEED

so if you drive 300 miles on 10 gallons fuel (averaged fill ups)
the the true miles is 285 miles and 28mpg.
if the odometer shows 150 miles and 10 gal, then that is 143 miles and 14mpg. Not 15 using corrected speedo or GPS total distance.
the missing CAT renders EGR dead for ever, so forget EGR it will never work lacking CAT backpressure stock ,sorry.

the CEL lamp is dead, well that is first. it needs to work , many of these cars, have it removed by nasty PO's, that hide faults. (classic)
the #18 lamp is sold in stores.
http://www.fixkick.com/CEL/CEL.html

if the cell is on, that means limphome mode, code 51 may or may not trip LIMPHOME mode.
if the good lamp is dead that mean the ECU is in BACKUP mode, and will do 10mpg easy in that mode, horrid MPG,

that B60 AT ecu will run ok, i got 28mpg with wrong ECU like this in 91 MT 5 speed car..
the only issue is the A/T park pin input to the ECU needs to be correct. (make it work like the clutch switch did)


how do you measure MPG, ?
filling up tank 100% same gas station even same pump and never top off, or force past out shut off?
then average 3 tanks,
then only use GPS total miles,?(Garmin GLS or ? tom tom or >? some why)
the key to good MPG readings is full tanks driven to 1/8th full, then repeat and averaged. (and use GPS to end the uselss speedo errors)


are the spark plug tips white or jet black.????
with no cat the exhaust on your car will be rich in nasty toxic NOX (nitros oxide stench from hell) keep the windows up. GRIN.

that is all for now good luck to you on your old kick.

First post, thanks for reading!

92 Geo Tracker LSi 2D 4WD 8V 5MT FED has been hacked on extensively by previous owners and a little myself.

I've put about 4000 miles on it in a year and a half and it runs great. At least I think so, it's the only one I've ever driven. Starts and runs smooth, will run 80MPH down the highway. This is my daily driver but only about 5 miles a day. Despite running well it gets an estimated 10MPG which now concerns me since my commute will be going to 60 miles per day shortly.

The driveline and suspension are unmodified and it has 27x9.50 tires on it now, most of the miles I put on were on 235/75's. I've been searching and reading for days and have identified some key contributors to the poor gas mileage.

#1- No cat and an oversize short exhaust. It has a header with EGR tube. I suspect the lack of back pressure is causing the EGR to not function properly.

#2- The EGR valve was plugged up. I cleaned it up as well as the ports although I didn't have a way to get any more than a couple inches into the exhaust port. It passed the stall test after clean up. Live test shows the diaphragm moving a little but I suspect not enough due to the lack of back pressure. No bark with valve installed.

I have no CEL not even when forced on by jumping ECU pin B13 to chassis ground. I suspect the bulb has been removed, will verify. I need to do that so I can check codes. There are a couple things I need help figuring out before proceeding.

#1- Am I in fail safe mode? Warm idle is 800, runs smooth, plenty of power, no RPM limit, no hesitations or stalls, no black smoke. Winter weather cold idle would rev up and down between 2000 and 3000 RPM until warmed up, then 800. Terrible exhaust fumes and terrible gas mileage.

#2- The sticker on the ECU has P/N -56B60 and says FED-AT. I see that P/N described as being for a 94 with auto trans-I'm 92 with manual trans. I don't know how many doors or valves that ECU is for. Anyone have further details on this ECU and/or any input on how badly wrong it is for my application?

Thanks again for reading!