Ford 4.9L
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Mountain Pass
Joined: Jun 2015
Posts: 128
Likes: 9
From: Louisville, Kentucky
Ford 4.9L
Is it just me or does Ford 4.9L engines run rich? I have a 1988 that appears to run rich and, as I recall, every 4.9L I have been around smelled like it was running overly rich. Has anyone experienced this, and if so, what would cause it? On my engine I have changed every sensor and replaced them with Motorcraft sensors and it still seems to run overly rich.
Hotshot
Joined: Jul 2020
Posts: 10,548
Likes: 2,668
From: Near Salt Lake City
Seems rich?
Smells rich?
Have an IM test done and see if the CO is down around 0.05 or so like it should be
If it fails an I/M test meaning over 1.2 percent CO. then you are rich
Some vehicles get to where they are over 3 percent (pig fat rich) if your MAP sensor goes nuts or ECT sensor thinks its 40 below for instance
I agree, Check the codes
Smells rich?
Have an IM test done and see if the CO is down around 0.05 or so like it should be
If it fails an I/M test meaning over 1.2 percent CO. then you are rich
Some vehicles get to where they are over 3 percent (pig fat rich) if your MAP sensor goes nuts or ECT sensor thinks its 40 below for instance
I agree, Check the codes
Hotshot
Joined: Jun 2015
Posts: 12,879
Likes: 2,446
into the intake manifold.
Lead Driver
Joined: Sep 2002
Posts: 9,555
Likes: 2,035
From: North Texas
Or injectors stuck open... The newest of this era is 26 years old. They all need fresh injectors.
Too many variables, not enough knowns.
Too many variables, not enough knowns.
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Tuned
Joined: May 2019
Posts: 480
Likes: 141
From: NJ
Yes, I know what you're talking about. It's primarily attributable to how precise and efficient modern cats and fuel injection are in comparison. 4.9's smell like they're rich, even if they're not and the cat is working. It's just the nature of 80's emissions controls. My '90 runs perfectly, gets ~17MPG, and smells so rich it could make your eyes water.
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Hotshot
Joined: Jul 2020
Posts: 10,548
Likes: 2,668
From: Near Salt Lake City
Lean misfire is the cause of burning eyes and bad HC stink in most cases
and pig fat rich is black smoke and you really do not smell any HCs
Your 88 has injectors that need to be cleaned possibly
Have it done right, through the fuel rail and do not add any injector cleaner to the fuel tank
and pig fat rich is black smoke and you really do not smell any HCs
Your 88 has injectors that need to be cleaned possibly
Have it done right, through the fuel rail and do not add any injector cleaner to the fuel tank
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