Engine Knocking at Idle
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Senior User
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From: Darby, PA
Engine Knocking at Idle
I recently changed plugs and wires, coolant and oil. I have noticed that the engine has a pronounced knock at idle when engine is at operating temp. It doesn't knock on acceleration or when the engine is cold. I have 96K+ on my 2000 FFV 3.0. Is this just from engine wear, blocked passages or something else?
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From: Dexter, MI
Did you disconnect battery cables for a half hour or so to allow ECM memory to be cleared? With new plugs and cables, the engine has a new set of operating conditions. Until you clear the memory you will be running on an outdated set of conditions.
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From: Darby, PA
Originally Posted by michigan66
Did you disconnect battery cables for a half hour or so to allow ECM memory to be cleared? With new plugs and cables, the engine has a new set of operating conditions. Until you clear the memory you will be running on an outdated set of conditions.
No I didn't. I thought the PCM would automatically read the current conditions and adjust. Thanks, I'll do that tonight when I get home. My wife is going on a long trip this week and was concerned as I haven't heard this noise before.
Laughing Gas
Joined: Jan 2005
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From: Magnolia, TX
azu,
I really suggest you unplug the NEG battery cable for several hours, not just 30 minutes. There's enough capacitance in the PCM circuitry that the memory could still hold the "old" data tables for longer than 30 minutes.
Just disconnect the NEG overnight.
CMOS
I really suggest you unplug the NEG battery cable for several hours, not just 30 minutes. There's enough capacitance in the PCM circuitry that the memory could still hold the "old" data tables for longer than 30 minutes.
Just disconnect the NEG overnight.
CMOS
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Changing plugs and wires will not effect computer operation requiring a computer re-set. Normally only when you change sensors do you need to re-set the memory.
If you clear the memory, the truck may run like crap while it re-learns the settings. 30 minutes is more than ample time for memory re-set. I do it in a lot less.
Changing the plugs wires wouldn't cause a "pronounced" knock at idle anyway. If the knocking is only at idle, try slightly increasing engine speed while listening to the noise. Try to locate where is coming from. Loose bolts on the torque converter or flex plate will cause a knocking at idle and dissappear as rpm increases. Most times it is more of a "thunking" sound than a knock. jd
If you clear the memory, the truck may run like crap while it re-learns the settings. 30 minutes is more than ample time for memory re-set. I do it in a lot less.
Changing the plugs wires wouldn't cause a "pronounced" knock at idle anyway. If the knocking is only at idle, try slightly increasing engine speed while listening to the noise. Try to locate where is coming from. Loose bolts on the torque converter or flex plate will cause a knocking at idle and dissappear as rpm increases. Most times it is more of a "thunking" sound than a knock. jd
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From: Darby, PA
You got me thinking now. I will inspect the source more closely but I believe it is coming from the front of the engine. With that said, and having it happening at idle, I am now thinking Harmonic Balancer is on it's way out.
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From: Darby, PA
Ok I checked things out further. Noise is not Harmonic balancer. It only knocks now at start up and sounds like lifter tap. Must be an oil flow problem. I'll change the oil out and use a flush to clean it out. I probably should drop the pan and clean pan and screen but I'll try this first. I change the oil every 5K so I doubt it could be sludged up, but it could. What type engine flush would you recommend? I usually use Gunk in the silver aluminum can.
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From: SW Va
Azu, you said you didn't hear the engine knock before you changed the oil & filter, so did you use the specified weight oil & Motorcraft filter, for this engne?????
Some brand filters are known to cause start-up knock & if for some reason the pressure drop accross the filter is too great, you might have lower than normal oil pressure at idle. Too viscous a lube won't help either.
Some brand filters are known to cause start-up knock & if for some reason the pressure drop accross the filter is too great, you might have lower than normal oil pressure at idle. Too viscous a lube won't help either.
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From: Darby, PA
I didn't hear any engine noises until recently. I changed the oil about 1000 miles ago and used 10w30 oil with a Purolator filter. Last filter was Fram. I usually use Purolator or Motorcraft oil filters. It might be the gas we were using. The station that we get our gas has been shut down a few times in the past week for unknown reasons to us. I know my Taurus was running like crap last week and when I filled up at a different station the car came back to life. Must be bad gas there. I'll check the truck again when my wife gets back from Watkins Glenn this weekend.
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From: SW Va
Well 5W-30 was, or 5w-20 now, is specified for your 3.0L & Fram filters have been known to cause start-up knock.
I don't think I'd try a engine flush, as it could stir up some mischief.
If you've changed oil as specified in your owners manual, for your type of driving & have used filters & oils that meet or exceed Fords specifications, you don't likely have deposits that require an engine flush imo.
A premium, fully formulated, motor oil like Ford specifies, has everything already mixed in it, that our engines require, including detergents to keep it clean.
If your still bound & determined to pour something in anyway, I wouldn't use a solvent based "flush" product.
I don't think I'd try a engine flush, as it could stir up some mischief.
If you've changed oil as specified in your owners manual, for your type of driving & have used filters & oils that meet or exceed Fords specifications, you don't likely have deposits that require an engine flush imo.
A premium, fully formulated, motor oil like Ford specifies, has everything already mixed in it, that our engines require, including detergents to keep it clean.
If your still bound & determined to pour something in anyway, I wouldn't use a solvent based "flush" product.
Laughing Gas
Joined: Jan 2005
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From: Magnolia, TX
Good news azu!
I'm not too big on any specific brand of gas but it is important to get gas from a station that frequently refills its tanks. Buy gas from busy stations and you'll be good most of the time.
CMOS
I'm not too big on any specific brand of gas but it is important to get gas from a station that frequently refills its tanks. Buy gas from busy stations and you'll be good most of the time.
CMOS
Post Fiend
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Easy fix, just keep it reved hee hee. Try some seafoam, 3.0's are bad to carbon up, it may help. Knocking and pinging are a couple of sytoms of carbon. I won't say it will fix it, however, it's cheaper than a rebuild.