Is a long term fuel trim of -7.81% anything to be concerned about? Since I bought a scanner/code reader I occasionally scan the ECU to see if anything's changed since I replaced the coils and plugs a couple months ago and most recently replaced the O2 sensors and the MAF sensor - it's a high mileage car. Anyway, I noticed when driving long distances the long term fuel trim will be about -.78 %, almost zero, but when driving short distances around the city it's usually between - 5.75ish to -6.75ish. Today it was -7.81%. Does that mean anything? Oddly enough, the short term fuel trim is always 0%.