[xjdavid]

I have a 94 XJ OBD1 and Actron 9690 OBD1scanner. It is telling me my ADPT fuel (long term fuel trim is 30% which I understand my PCM is supplying more fuel than normal.

I do have a small crack in the exhaust headers which I can hear when it is cold but not once it warms up. I have never worried about it till I bought the scanner. Whats every body's experience with this. Should I fix the crack?

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[4.3L XJ]

If you have a cracked header. it will suck air. This will register on the O2 sensor as being lean and then the ECM will supply more fuel to the injectors