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Chris (aka- Moose)
Chris (aka- Moose), Technician
Category: Ford
Satisfied Customers: 48676
Experience:  16 years experience
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Ford Ranger 4x2: 2003 ranger 3.0 v6 flashing engine light once

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2003 ranger 3.0 v6 flashing engine light once youhit highway speed of 65 to 70 it boggs down chugs have replaced plugs wires coil pack cleaned mass air flow sensor. what else do i need to do?

Hi, I’m Chris. Welcome and thanks for asking your question!


Have you narrowed it down to just one or two cylinders causing this?

Is it always this cylinder(s) or is the concern moving around to random cylinders?


Customer: replied 5 years ago.
sometimes code is #4 sometimes #6 sometimes just cyl misfire system to lean those are the three codes. it runs fine unless you hit 65 mph then the problem starts

Have you ran a cylinder compression and leak down test on every cylinder?

Have you done anything to address the lean codes?

Customer: replied 5 years ago.
no sir,
we did the plugs,wires, coil pack, mas air flow sensor

One common issue on this engine is the valve seats getting crushed and flattened out and causing the compression to a be a little lower resulting in a misfire under certain loads. The cylinder compression and leak down test will tell you if that head needs to be replaced.


You then need to check and see if the source of the misfire is the lean codes. Low fuel pressure from a clogged filter or weak pump can cause both concerns. leaking intake gaskets or PCV or vacuum hoses can cause both concerns.


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