My car has a fuel trim of positive 27. When I rev it up to about 3000 rpm it goes down to about 15. And when I remove the map sensor (Im pretty sure it doesnt have a maf sensor, but I could be wrong) it drops from 27 to 11 at idle. I also left the sensor unplugged over night and LTFT dropped back down to zero, but it’s just climbing back up slowly again.
do you think its a vacume leak, bad map sensor, or maybe both? My downstream o2 sensor (I believe) goes everywhere when I give it gas. It might be bad, or the cat is bad it does say its at 57 percent efficiency.
But im not sure about my upstream o2 sensor. If I understand correctly and if I’m looking at the right one on my scanner (it says wide range o2s bank 1 sensor 1), it might be bad. Im not fully sure. I reduced the graphing range on the graph to the smallest numbers, but it still just looks like a straight line.
This is a picture of the graphs while driving.
do you think its a vacume leak, bad map sensor, or maybe both? My downstream o2 sensor (I believe) goes everywhere when I give it gas. It might be bad, or the cat is bad it does say its at 57 percent efficiency.
But im not sure about my upstream o2 sensor. If I understand correctly and if I’m looking at the right one on my scanner (it says wide range o2s bank 1 sensor 1), it might be bad. Im not fully sure. I reduced the graphing range on the graph to the smallest numbers, but it still just looks like a straight line.
This is a picture of the graphs while driving.
Mar 9, 2026 at 3:32 PM
