I started a new thread because the original was very far back. To
fill you in, though, I followed directions from a site I was referred
to to fix the service engine light which comes on with codes 171 and
174. I cleaned and then replaced the maf sensor, the IAT sensor, one
oxygen sensor, the engine control coolant sensor and the dpfe. The
car has also been tuned with new plugs, pcv valve and air cleaner.
I remain suspicious of a manifold vacuum leak, partly because one
manifold bolt wasn't tightened well after replacing the alternator and
also because there are few possibilities left. The fuel trims you
refer to are the adjustments made by the PCM, is that right?
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