Best replacement injectors

[acschilling]

I think the the knock my 4.0 OHV has been experiencing is from an injector that is going. Two days ago I replaced the Bosch wires and NGK plugs with motorcraft wires and $5 motorcraft plugs. It has a noticeable miss on cold starts (like a fairly "weak" start, if you will) followed by knocking till it warms up. It has recently declined from knocking for 10+ mins down to <5 mins. Once warm it's smooth as butter (was smooth with old plugs and wires as well). If I pop the hood while its running I can hear a rapid "tick" somewhere near the intake. I think it might be an injector, if it is I found these on Amazon:

http://www.amazon.com/Motorcraft-CM...r=1992|1992&carId=001&n=15684181&s=automotive

are these the safest bet as far as getting as OEM as possiblse. Thanks!

P.S. I would love to read stories from those with any experience with "tick-y" OHV injectors.

 

[Anime]

I would guess that the "tick" you're hearing is more likely to be a collapsed lifter (or lifters) or just the common worn rocker arms than it is anything to do with an injector.

Once the lifter "fills up" with oil that is circulated and is at warmer temps, it's no longer relying on the internal spring. On the collapsed lifters, that spring is broken and so the lifter clatters around without the tension between the camshaft and the pushrod until there is oil inside it, creating the "tic-tic-tic" sound.

It could be other things, even just a worn timing chain and tensioner and/or old and dirty sensors creating an environment where timing isn't perfect and old and worn parts contribute to things being "off" just enough to make some noise.

Depending on mileage and what has been replaced internally, it might even just be dirty/clogged injectors or fuel system deposits. The engine in mine had serious ticking and an incredible knock when driven hard that felt as if a giant sledge hammer was hitting the passenger side of the engine block every time it knocked - which was almost once a second when really hit the gas. Use of some STP fuel injector cleaner (black bottle) and only getting top tier gas (Chevron/Shell) from then on fixed it after a few weeks//months and the tick and knock has gone. There is still valve clatter from worn rocker arms, but once I get new ones installed and a new timing chain kit, I expect it will be quiet like new and running great.


As far as injectors go - you need to look at the injectors on your particular vehicle to match them up. Some of the 91-92 Explorers might have the Black CM4681 injectors, but that may have just been the earlier ones made in 90-91, most 4.0L OHV's use the Red (they are only red on the connector end and the rest is black, so don't get confused) CM4749 injectors.

That is a FANTASTIC price on the CM4681's, even though only two are available. If your rig has black injectors, I would seriously consider buying them to replace any injectors that are bad or that go bad in the future.

That said, you can also "upgrade" to the Red injectors if I remember right - I don't think any modification is necessary as they were just a part to address fuel injector fouling/clogging issues with the older designs and part of the reason the 93-94 Explorer motor had slightly better HP/torque numbers than the 91-92. There may be more to it than that, though.

 

[acschilling]

You're the man Anime. Always appreciate the knowledge you drop. Your description of how the lifters work is helping me understand them a little better. I may have mentioned in a previous post that I seafomed the brake booster line and the "tic" on start ups went away for a few mornings-only to return.

At that point I installed motorcraft plugs and wires. Ran noticeably better when it warmed up. Still cold "tic" tho.

I can lay on it going up hill and such without much trouble or strange sounds. Sometimes the low-end is sluggish but I just attributed that to the larger tires and 3.73s.

I've also read exhaust leaks may cause a cold miss, rough idling, and possible knocks/ticks. Is that just for the 5.0? Thinking THIS may be my issue I inspected it and found the outside facing bolt on the exhaust manifold that connects to the Y-pipe is noticeably backed out. The stud isnt as far through the hole as the other. Can a possible leak like this cause low pressures inside the engine and a "tic"?

 

[Anime]

Exhaust leaks can make weird sounds or cause weird problems, but of all the 4.0L OHV's I've heard with exhaust leaks, they just sound loud like you'd expect - a deep ratty rumble like a big motor without a muffler.

If the bolt is just backed out, I'd say use a wire brush to clean up the threads that are exposed, then get under there with a ratchet, socket and extension (a 20" makes it easy) and tighten that bolt back up. If the noise and issues go away you'll know what it was.

 

[smegun]

when the x is low on fuel i will hear a little lifter clatter in one of my cylinders but on a full tank there is no clatter the theory is that one of my injecters is a little clogged or the order of fire has somthing in mind there is a new fuel pump in my truck and things are better with better gas a little tick is not too much to worry about totally cold but havnt changed the fuel regulater yet or delved for a new set of injecters looks a set to be had for a 100 on ebay let me know which brand and model of injectors to get to get when you figure out where your tick/ clatter is comming from