Thread: Fuel Trim Diagnosis

Originally Posted by Cambo@oldjaguar

You need to smoke test it to find the leaks.

However, the o-ring gaskets on the intake manifold, where it meets the heads, are known to deteriorate and cause vacuum leaks, common enough 4.0 problem.

These ones? 2005-2009 For Landrover Discovery Series 3 4000 Cologne Intake Manifold Gasket | eBay

Welp.. took the MAF out, saw some greenish corrosion on one of the wires up in the belly of it and scratched it off with a pin. Also put a new air filter in and after a couple short trips the CEL cleared by itself. LTFT still showing slightly rich at idle but max -10%. Not sure whether it was the filter or MAF, but have a new sensor coming anyway