Surging and backfiring through intake at start up

2001 FORD RANGER
200,000 MILES • 2.3L • 4 CYL • 2WD • MANUAL
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KEVIN HUDSON
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As soon as engine cranks. It begins to surge and backfire through intake. I have replaced throttle sensor and map sensor already. New plugs and wires, new coil. The problems still there. Any idea where to look next?
Mar 25, 2018 at 7:47 AM
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PATENTED_REPAIR_PRO
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The backfire can be because of several things, such as a jumped timing chain/belt, a intake manifold vacuum leak, an intake valve not seating all the way, a blown head gasket. Or even a too lean fuel mixture, maybe due to weak fuel pressure so I would check the fuel pressure, check for any fuel injector trouble codes or any codes for that matter.
Then, completing a engine compression test to rule out the timing chain/belt, the intake valve not seating and the blown head gasket. If all the cylinders are good and about even, then I would suspect an intake manifold vacuum leak.
Mar 25, 2018 at 8:16 AM
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KEVIN HUDSON
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It started all at once one morning when cranked it up to warm. Compression is good and i have looked for vacuum leak. I have not checked fuel pressure yet. But will. Keep thinking it is running lean on fuel. Timing is also correct.
Mar 25, 2018 at 8:42 AM
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PATENTED_REPAIR_PRO
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Are you getting any trouble codes for the o2 sensors?
Mar 25, 2018 at 8:50 AM
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KEVIN HUDSON
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Not getting any error codes.
Mar 25, 2018 at 6:51 PM
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PATENTED_REPAIR_PRO
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The fuel pressure should be 60-65 psi KOER and/or KOEO.
Mar 26, 2018 at 8:00 AM