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

355

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

242,255

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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