Does my 4.0 need cold air?


Denisefwd93

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Not based on what the aftermarket sellers are offering but because the stock air intake tube is missing from the airbox along with it hot air ducts from the manifold missing I feel I need to do something,. Should I at least get a flexible 3 inch round and duct it from behind the grill next to the radiator to the airbox? Cleaned the MAF not even six months ago it pings pretty bad again,when it's warm or hot outside. In any case, I don't want hot under the hood air going in the intake right?
 


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As beneficial as cold air is to performance you won't notice much difference. My hood duct has been missing since I moved three years ago, I haven't missed it enough to go find one.
 

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Does it "need" it, no, is it better with it, yes

Its called the Inlet Duct, 1993 4.0l would use FO7Z-9A624-C part number I think, which is "no longer available", lol

Yes, you could use flexible duct to plumb in cooler fresh air, either thru the front of rad support as Ford did or just down lower in engine bay
Air should not be all that hot in engine bay where the inlet is on air cleaner box now

Back when there were carbs sitting on top of the engine where ALL the hot air lived, lol, was when the Cold Air Intake got its start, and it really made a difference then
With air filter off to the side and lower down, when using fuel injection, it isn't such a big deal


As far as pinging in warmer weather, you could try another IAT sensor, air temp sensor, that's on the upper intake of the 4.0l OHV
If you were to used 91 octane does the pinging stops completely?
 

Denisefwd93

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IAT sensor.... Ok
Ping stops with 90 +
I'm quite sure I can rig up some type of cold air intake after a whole lifetime in HVAC Lol

Than you!
 

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Pinging "starts" above 90degF?
 

Denisefwd93

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Sorry, 90+ octane. No ping

And yes it does start to ping when the temperature reaches upper 80s 90s because it gets quite hot underneath the hood that goes without saying.

Also it does not ping, when it's very humid and raining I mentioned that on another thread once.
 

RonD

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Could be running a bit Lean then

4 Liter engine computer already knows exactly how much air is coming in at any RPM with any Throttle position, its just Math which is what the computer does, on the fly fast math calculations
4.0l engine will pull in 4 liters of air every 2 RPM at wide open throttle, so math just works backwards from there, but thats all been done and is in tables in computers memory

MAF sensor is there to tell computer the WEIGHT of the incoming air, because air:fuel ratios are all by weight not volume
Computer is set for sea level air weight at approx. 65degF outside air temp, I believe

MAF sensor works by sampling about 10% of incoming air, it uses a heated wire that is cooled by the air passing by it, how much it is cooled allows computer to calculate its weight, based on RPM and throttle position

colder air is heavier so requires more fuel to be added
Higher elevation has lighter air so less fuel added

humid air "acts" as colder/heavier air because moisture cools the MAF more than dry air, so computer adds more fuel

So if it pings less with humid air that dry air at the same outside temp I would guess Lean mix when air is drier

It will be a small difference in a sensor since it only does it with warm dry air
 

Denisefwd93

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I'll rig up a duct, clean the MAF, maybe get an IAT it's not very expensive.
For the first time since I've had this truck (almost exactly a year) I can actually drive at highway speeds!
Thanks!
 

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Also if the MAFS is dirty it will not “see” all of the air that flows over it, making the processor think the air flow is less than it is. That will result in lean conditions, at least when it is open loop.
 

Denisefwd93

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I cleaned it last summer it was very very dirty but I don't think would be dirty again but it's easy to do with the right security torx now that is in the collection
 

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Yes, a coating of "dirt" on the MAF acts as an insulator so air flow doesn't cool the sensor as much, so computer sees/thinks lighter air so adds less fuel.
 


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