Originally Posted by robertf03
Nice, any idea why it started running rich?
I'm very happy with the tune I got on my 4.6. Averaged 13.5 mpg with 35s, roofrack, and probably 1500 lbs of crap out to Moab and back.
None at all. It's low km (~100,000 miles) and when I got it would run so rich it would paint the ground black under the exhaust.
It also had the wrong tune resistor fitted, dead thermostat, unsealed plenum, idle set wrong etc. This is open loop so no O2 sensors to correct it.
For some reason it's currently still switching fuel maps. I'm wondering if I accidentally had it tripped into limp mode and remapped the limp-mode-map to run normally. So it runs rich when it trips out of limp.
I'll fix this by writing the same values into limp and normal running.