Running lean

[spooner1129]

Ok guys I posed here a while ago with a misfire at low rpm under a load and changed pretty much everything and put a set of autolite plugs in it coil pack wires injectors nothing seams to help. I pulled some plugs yesterday and found out that every cylender is running lean plugs super clean no carbon diposits electrode is shines yellow. I have about 600 miles on these plugs and they really don't look like they should. Please any help yould help me out so much as I have to drive 2 hours here soon and I would love to get it fixed I'm out of ideas thanks

 

[evanesce69]

here are just a few things that could cause a lean condition...

low fuel pressure
fuel filter
weak fuel pump
failing fuel pressure regulator

dirty injectors

faulty O2 sensors

vacuum leaks around the intake manifold

faulty MAF

 

[RonD]

Is the engine pinging/knocking under load?
If there is a Lean mix it will

Is the misfire gone?
misfires cause false Lean

 

[spooner1129]

Ron d I'm not really hearing much knocking or pinging. Judging by the spark plugs looks like it's running lean. Evanesce69 I replaced fuel filter already checked fuel pressure running it never went below 63 psi key on it went right to 68 and slowly dropped to 45 I changed fuel injectors on the cylinders that were misfiring #1 and 6 also checked for vacume leaks numerous times never found a thing I Eagan took it to a shop for the smoke test. Turned up nothing m. But the mis Fire is still. The more I drive it the hotter the engine gets the worse it seams to get

 

[evanesce69]

interesting...

45 should be the working static pressure in the fuel system, was that measurement with the engine running, at idle ? if the pump cannot supply enough volume the static pressure would appear normal at idle, but under a load the pressure may decrease due to fuel starvation... too bad you couldn't check the duty cycle on the injectors under your average driving condition... that would be a very good indicator to your fuel systems condition.

although you could also measure the fuel pressure while driving if you have then means. would give you a similar indication.

 

[TxGasRacer]

http://troubleshootmyvehicle.com/ford/4.0L/troubleshooting-P0171-and-P0174-page-1 http://troubleshootmyvehicle.com/ford/4.0L/how-to-test-a-misfire-1

 

[evanesce69]

this may sound dumb, but a new cap, rotor and wires could fix the misfire...

you could perform a compression test... i don't recall the spec, but the values should be consistent across all cylinders. low compression can act like a misfire too.

how many miles are on the engine? do you know it's history?

 

[RonD]

Ron d I'm not really hearing much knocking or pinging. Judging by the spark plugs looks like it's running lean. Evanesce69 I replaced fuel filter already checked fuel pressure running it never went below 63 psi key on it went right to 68 and slowly dropped to 45 I changed fuel injectors on the cylinders that were misfiring #1 and 6 also checked for vacume leaks numerous times never found a thing I Eagan took it to a shop for the smoke test. Turned up nothing m. But the mis Fire is still. The more I drive it the hotter the engine gets the worse it seams to get

Your 2005 3.0l Ranger falls in the 2004-2006 3.0l Ranger TSB about bad exhaust valve seats.
The exhaust valve seats would get loose and recess into the head so cylinder wouldn't be sealed for compression, this would cause misfires.

TSB 05-26-3

FORD: 2004-2006 Ranger

ISSUE
Some 2004-2006 Rangers 3.0L-2V "Vulcan"vehicles may exhibit:
- Malfunction indicator lamp (MIL) on with diagnostic trouble codes (DTCs) P0300-P0306 and P0316
- Rough running at various RPM
- Rough idle
- Misfire

ACTION
This may be due to an engine exhaust valve seat recession causing a loss of compression. Refer to the following Service Procedure to diagnose exhaust valve seat recession.

SERVICE PROCEDURE
1. Perform a power balance rest to clarify if a cylinder is misfiring. Identify and keep record of any cylinder that has a concern.

2. Perform a manual compression test with the spark plugs removed to locate any cylinder that may have low compression. Refer to the appropriate Workshop Manual, Engine System, General Information, 303-00.

3. If no low compression is found per shop manual instructions, proceed with normal misfire diagnostics per the Powertrain Controls/Emissions Diagnosis (PC/ED) Manual for the appropriate model year.

4. If low compression is found and it is a cylinder that had a misfire on power balance, perform a leakdown test to determine the source of leakage that may be causing the low compression. Refer to the appropriate Workshop Manual, Engine System, General Information, 303-00.

5. If low compression is found in a cylinder that did not have a misfire detected then proceed with normal base engine diagnostics per the Workshop Manual, Engine System, General Information, 303-00.6.

If the exhaust valve is identified as the source, replace both cylinder heads with the newly released service cylinder heads. Refer to the appropriate Workshop Manual, Section 301-01A.

PART NUMBER / PART NAME
6U7Z-6049-A / Cylinder Head Assembly
2F1Z-6079-BB / Upper Gasket Kit
F8 DZ-6065-AA / Cylinder Head Bolts
F7DZ-9448-BB / Engine Exhaust Gasket
4F1Z-658-AA / Valve Cover Gasket
F6DZ-9439-C / Side Gasket
F2DZ-9A425-AA / China Gasket (Front)
F3DZ-9A424-BA / China Gasket (Rear)
4L5Z-9H486-AA / Gasket-Upper Intake Manifold

So do a compression test

 

[spooner1129]

The fuel pressure was at 65 and dropped to around 62 when I revels it up a bit then when back at idle went back up to 65 68 psi I did a compression test all cylinders checked out around 155 165 then I also performed a leak down test in all cylinders with 45 psi in the cylinders and piston at tdc and I could not find and leaks from exaust. The exaust valve seats wat on of the first things that popped in my head because I read about it before I bought the truck. And not much history on it except for I bought it with 70k on it it now has 113 k on it it sat for 3 weeks I started it ran it for a few day the check engine light came up as a cylender 6 misfire and now I'm here

 

[spooner1129]

I am no opposed to replacing the engine instead of the heads. I work at a salvage yard and can grab a motor with 60k on it for the same price as new heads. I just thought this on could be salvaged

 

[Rearanger]

Scan tool for fuel trims might help.