04-21-2019, 05:02 AM
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!
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!
1992 Geo Tracker LSi 2D 4WD 8V 5MT FED been hacked on extensively