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Surging and backfiring through intake at start up

Tiny
KEVIN HUDSON
  • MEMBER
  • 2001 FORD RANGER
  • 2.3L
  • 4 CYL
  • 2WD
  • MANUAL
  • 200,000 MILES
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?
Sunday, March 25th, 2018 AT 7:47 AM

5 Replies

Tiny
PATENTED_REPAIR_PRO
  • MECHANIC
  • 1,853 POSTS
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.
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Sunday, March 25th, 2018 AT 8:16 AM
Tiny
KEVIN HUDSON
  • MEMBER
  • 3 POSTS
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.
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Sunday, March 25th, 2018 AT 8:42 AM
Tiny
PATENTED_REPAIR_PRO
  • MECHANIC
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Are you getting any trouble codes for the o2 sensors?
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Sunday, March 25th, 2018 AT 8:50 AM
Tiny
KEVIN HUDSON
  • MEMBER
  • 3 POSTS
Not getting any error codes.
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Sunday, March 25th, 2018 AT 6:51 PM
Tiny
PATENTED_REPAIR_PRO
  • MECHANIC
  • 1,853 POSTS
The fuel pressure should be 60-65 psi KOER and/or KOEO.
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Monday, March 26th, 2018 AT 8:00 AM

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