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Misfire / lean run

K Thompson

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Age
71
Location
Highland Village TX.
Vehicle Year
2003
Make / Model
Ford Ranger XLT
Engine Type
3.0 V6
Transmission
Manual
2WD / 4WD
2WD
I have a 2003 Ranger 3.0l 5 sp stick. Love my little truck. Bought it 18 mo. ago after my Tundra was totaled. Anyway It had 152K miles when I bought it, and now has 165K. Has had new Motorcraft wires Autolite plugs SMP coil Motorcraft TPS SMP PCV valve and various vacuum hoses that were cracked. It has been running great until yesterday it suddenly acted like a plug wire came off. Soon got the CEL. Took it home scanner reports misfire on cylinder 2 and lean bank 1. Ok replaced plug and wire on #2. Ran the same. On the way home from the parts store, it suddenly began running correctly again (for about 1/8 mile) then back to missing again. It now only gives a lean code (P0171). I have a shop made smoke machine that uses regulated shop air to find vacuum leaks and could not find one. I also sprayed a can of carb spray around the lines and plenum with no increase in revs. The coil will make a blue hot spark about 1" long on each coil port. Would love to hear where you guys think I should go from here!!

Thanks again
The Boltman (Keith)
 


rusty ol ranger

2.9L Mafia-Don
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My credo
A legend to the old man, a hero to the child...
Injector plugging up or not opening is my guess
 

RonD

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Lean code means upstream O2 sensor is seeing higher Oxygen in the exhaust on that side of the engine, Bank 1 is passenger side
Cylinder 2 is on passenger side of engine

What happens when a cylinder Fires?
The fuel is burned up with the Oxygen

So when a cylinder Misfires............................
No Oxygen is burned up, and that Oxygen goes out to O2 sensor, and higher oxygen levels and then Lean Code

So Lean code is not symptom is if there is a Misfire, Lean code is the result of a Misfire, so until Misfire is diagnosed ignore Lean code

Test compression on 1, 2 and 3, or all 6 cylinders, even better
Take burnt exhaust valve off the menu, or find out it is the issue


If you have an intermittent misfire at idle, spray fuel into the engine while its idling, if misfire goes away then it could be faulty injector, if not then it isn't
 

K Thompson

New Member
Joined
Aug 16, 2021
Messages
20
Reaction score
16
Points
3
Age
71
Location
Highland Village TX.
Vehicle Year
2003
Make / Model
Ford Ranger XLT
Engine Type
3.0 V6
Transmission
Manual
2WD / 4WD
2WD
Thanks to Rusty and Ron for taking the time to help. I replaced #2 injector and she runs great again.

You all have a great holiday season and prosperous new year!!
 

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