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Rough idle
Hello,
Out of ideas for the cause of a rough idle issue with a 1994 ford ranger 3.0 liter, 6 cylinder. Bought the truck used and immediately changed plugs, plug wires, distributor, fuel filter, oil etc.....and it ran fine for a year and a half then all of the sudden half way into work one day it started acting like it was missing and wanted to die at stop lights. Thought maybe bad gas but adding fuel additive did not help. Replaced: Idle air control valve mass air flow sensor checked for vacuum leaks replaced fuel filter replaced pcv valve replaced pcv valve hose cleaned butterfly valve and linkage even though it did not appear carboned over with gook. |
Welcome to the forum
Does it run better or worse on cold start? Or no difference? Does it misfire at all RPMs and lack power? Generally speaking to save money and time the first thing you do when there is rough running is a compression test Pull out all spark plugs and inspect the tips, keep then in order, they tell you whats happening inside a cylinder Test each cylinder and write down results Pressure numbers don't need to be high but do need to be consistent across all 6 cylinders If you have 5 cylinders at 150psi and one at 120psi then you have a problem in that one cylinder, usually burnt exhaust valve No amount of outside repairs will fix it If all cylinders are within 10psi of each other then you can move on to spark or fuel issues, other wise you are wasting time and money "New" parts now-a-days can be a problem Unless its a Motorcraft part, or AC/Delco, its never ever been tested, you are the first, and if you are troubleshooting a problem then a new part can just add to the problem, lol Spark plugs, PCV, filters and cleaning are fine to change, sensors are another matter, my 1994 still has all its original sensors, only new O2s since they do wear out every 12 years Vacuum gauge can also be handy for any gasoline engine Vacuum at idle can tell you a lot and when REVing, clogged intake or exhaust can show up |
94 ford ranger rough idle
Originally Posted by RonD
(Post 2220555)
Welcome to the forum
Does it run better or worse on cold start? Or no difference? Does it misfire at all RPMs and lack power? Generally speaking to save money and time the first thing you do when there is rough running is a compression test Pull out all spark plugs and inspect the tips, keep then in order, they tell you whats happening inside a cylinder Test each cylinder and write down results Pressure numbers don't need to be high but do need to be consistent across all 6 cylinders If you have 5 cylinders at 150psi and one at 120psi then you have a problem in that one cylinder, usually burnt exhaust valve No amount of outside repairs will fix it If all cylinders are within 10psi of each other then you can move on to spark or fuel issues, other wise you are wasting time and money Thanks for the info......problem fixed.........02 sensor. "New" parts now-a-days can be a problem Unless its a Motorcraft part, or AC/Delco, its never ever been tested, you are the first, and if you are troubleshooting a problem then a new part can just add to the problem, lol Spark plugs, PCV, filters and cleaning are fine to change, sensors are another matter, my 1994 still has all its original sensors, only new O2s since they do wear out every 12 years Vacuum gauge can also be handy for any gasoline engine Vacuum at idle can tell you a lot and when REVing, clogged intake or exhaust can show up Thanks for the info......problem fixed.........02 sensor. |
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