96 f250 P0171&P0174 need help passes all vac test

Asked by Mar 19, 2016 at 04:02 PM about the 1999 Ford F-250 Super Duty XL LB

Question type: Maintenance & Repair

Don't see anything visually don't see anything wrong with live data passed all
vacuum test

4 Answers


Check mass air flow sensor ...as well possible ecm may need update ...

Mac passed mode 6 test how about a restriction like low flow injector but that shouldn't give me a lean condition in both banks a weak fuel psi regulator I'm leaning too

Sorry meant maf not mac


Those codes are classic lean codes, Unmetered air is being detected after the MAF. You said you did a vac test? I d perform a smoke test. Might be a small hose or gasket.

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