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Replacing IMRC Actuator
&
Cleaning Secondary Intake Ports And Valves |
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Replacing the IMRC actuator (controller) is my first major adventure into the 4.6L DOHC engine. Other than pulling the intake cover off to installing a set
of 36lb/hr injectors and oval FRPP TB, I haven't really done much wrenching on it. I have to say thay it was just about as easy as pulling the intake on a 5.0 L engine - and, in some respects, easier. Now for the details.
I started by removing
the strut tower brace, relieving the pressure in the fuel system, draining the coolant. Relieving the pressure in the fuel system can be accomplished by applying a vacuum to the fuel pressure regulator or pulling the fuel pump fuse and attempting to
start the car - or as some have suggested...just letting it sit long enough without starting the engine. Although coolant does not flow through intake manifold of the 4.6L DOHC engine, the coolant must drained. Removing the intake manifold requires
that the coolant flow tubes (located above the alternator) be detached from the front of the block. The coolant flow tubes have mounting tabs that are captured by the front two intake manifold stud-bolts. The coolant flow tubes must be detached from
the stud part of the stud-bolts for allowing these two stud-bolts to be removed.
Because of the location of the thermostat, the coolant must be drained from the radiator via the radiator petcock and by draining coolant directly from the block by
detaching the hose from the thermostat housing as shown in the picture below. As best as I can tell, draining the radiator does not result in the coolant being drained from the block. As a result, coolant would pouring out of the block at the coolanr
flow tube passages as the coolant flow tubes are detached from the block. |
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As depicted in the picture blow, once the coolant is drained, the flow tubes can be detached from the block and moved forward to gain access to the two front
intake manifold stud-bolts. The ignition wire bracket also needs to be removed. |
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Next, I removed the intake cover, detached the fuel supply and return lines from the fuel rail, removed the fuel rail mounting bolts. After this, I removed
the 10 bolts/bolt-studs that retain the intake to the block. With these bolts removed, the intake manifold was ready to be removed…almost.
The IMRC actuator is mounted on the bottom of the intake manifold and the cables of the IMRC actuator
are routed through various branches of the electrical harness. I opted to lifted the intake manifold enough to un-bolted the IMRC actuator from the intake manifold and was then able to simply remove the intake manifold separately from the IMRC actuator
and IMRC plates. I'm not sure if this the "the" way to do it or just one way to do it. In any case, it worked just fine. The IMRC actuator mounting bosses of the intake manifold can be seen in the picture below. |
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After removing the intake manifold, I removed the IMRC actuator and IMRC plates as an assembly. As mentioned above, the cables of the IMRC actuator are
routed through various branches of the electrical harness. Be sure to note how the cables are routed so that they are re-routed during re-assembly in a manner than does not result in the cables binding. The IMRC plates and IMRC actuator are shown, as
assembled, in the picture below. A shot of the internals of the IMRC actuator is also shown (for any one who really wants to know). |
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Now that the intake manifold and IMRC plates were out of the way, I could see just how dirty the IMRC plates and secondary intake ports/vales were. So dirty
were the secondary intake ports and valves that I had a hard time getting a picture that shows the build-up on the back of the secondary valves. If nothing else, the view into the primary port provides an idea of just who dirty the secondary ports and
valves were. (See pics below) |
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After a little cleaning, the IMRC plates looked like new. As for the secondary intake ports and valves, they were much better, but still not nearly as
clean as the primary ports. I cleaned the secondary intake ports using a 1" nylon bristle paint brush, a long narrow screw driver and carb cleaner. The 1" brush fit perfectly into the port and did a great job at cleaning up the ports, valve stems and
back of the valves. The long screw driver came in handy for gently scraping heavy deposits from the back of the valves and for pushing strips of rags down into the ports for soaking up the carb cleaner. I had to index a crank a few times to make sure
the valves were closed when cleaning all of the ports/valves. One good sign was that each secondary ports held the carb cleaner when the corresponding valve was in the closed position. The pictures below show the results of my cleaning
efforts...thumbs-up! Compared to what they looked like before, this is clean enough to eat off of...okay, maybe not that clean. |
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Everything went back together without a hitch. Ford's metal-polymer composite gaskets were in great shape so I re-used them. IMO, gasket technology has
seen some of the largest leaps in the automotive technological innovations. No more gasket cement, RTV, gaskets shifting during installation, etc… you gotta love that! Below is a picture of the IMRC plates and IMRC actuator ready for intake manifold to
be attached to the IMRC actuator and then dropped into place. |
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After getting it all back together, I hit the key a few times to prime the fuel system, cranked it over and it started right up. After refilling/burping
the cooling system and checking for leaks (coolant, vacuum, etc.), I took it out for a spin. The bucking/surging that I was experiencing is gone, resulting in noticeably smoother mid-range power delivery. Unfortunately, because we are having one of our
wonderful 100-degree days (in the shade, that is), I didn't get into boost too much. So, I wasn't able to see if I could feel any major difference under boost. I'll have to hake her for a spin this evening!
As a reference, it took
about:
1. An hour and 10 minutes to get everything disassembled;
2. 40 minutes to clean the IMRC plates;
3. 2 hours to clean the secondary intake ports and valves; and
4. 50 minutes to reassemble everything.
Hope this helps you
when it's your turn to do your IMRC actuator.
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Copyright 1999-2002 David O. Simmons
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