This IMRC rebuild was part of fixing an SPI after a dropped valve seat. Here's the promised pictures and some description:
The Intake Manifold Runner Control is an assembly that goes between the intake manifold and the cylinder head. V-8 Fords have two of them, but the SPI only has one. The IMRC is removed typically when removing the cylinder head, but can be rebuilt separately. I read that a common failure is of the IMRC's electric actuator, and I suspect some of these failures are because the internal parts are gooed up and making the actuator work too hard.
The IMRC is a butterfly valve assembly that opens under hard acceleration, for example. They are quite similar in principle to the secondaries on carburetors, and as with them, fuel economy likely is traded off for performance. If the IMRC sticks open, closed, or part way, or is sluggish to respond, both performance and MPG would be affected, IMHO.
Here's the IMRC assembly that came off the SPI I just finished rebuilding. The standard-size ball peen hammer is there for scale, not use!
![Image]()
Here's a close-up of one pair of "Split Port Induction" (SPI) ports in the IMRC, serving one cylinder. On the left is the normal-driving port with the hole at the top where the fuel injector shoots in the metered fuel. The other "secondary" port has the round butterfly throttle plate (technically a "damper", not a "valve"), and as you can see was heavily gooed with nasty black, oily stuff. The primary port also had this goo on its walls.
![Image]()
After getting the IMRC off the car, my next step was to remove the actuator. It's a sealed device unless you want to drill out the plastic rivets; this one hopefully works fine so I left it alone. I've read elsewhere that a OBD-II code will be thrown, and the Check Engine Light (CEL) will illuminate, if the actuator goes bad; this one didn't.
![Image]()
Next the throttle plates come out -- this was the most worrisome part because, from experience, it is easy to strip the little screws holding throttle plates on their shaft. I went through about seven of my Phillips screwdrivers until I found one that fit really well. Each screw was very tight, but came loose. Don't lose them! And note the position of the discs -- each of mine had a "Y" stamped on their top, and faced the opposite direction of the corroded/white-ish center "inverted tee" portion of the mating surface.
![Image]()
Next I carefully scraped the two mating surfaces of the IMRC's body -- they are fairly soft aluminum alloy and you definitely do not want to scratch their mating surfaces. Newbies should not use a steel gasket scraper like me, but I'm an old hand at this.
![Image]()
Next is the nastiest work, by far. Expect to use an entire can of carb cleaner -- read and follow directions! E.g., safety glasses, lots of ventilation (so do outdoors), fire precautions, etc. A couple of old toothbrushes (first one stiff, second one soft), some plastic scrapers, and rags were needed, as was a doubled, thick, large sheet of cardboard to catch the goo.
But be sure not to spray, get wet, or scrub the bearing/seal where the common shaft exits the assembly! You don't want to replace it unless necessary. The other end is sealed, and the bearings inbetween are just bore holes. At this point, don't even try to remove the shaft.
![Image]()
I separately soaked the throttle plates and their screws in a steel can. Then took them out and scraped/wiped the plates and screws, then repeated.
After the first pass at cleaning the body using carb cleaner and the first toothbrush, the common shaft then easily pulled out of the assembly. Here it is; handle/clean it carefully -- you don't want to bend it at all.
![Image]()
After lots more carb cleaner, etc., and a final washing with Dawn dishwashing liquid and water, and drying with compressed air and time, here what the body looked like. I wanted the secondary ports, and the fuel injectors' holes to be near-pristine, but for the sake of time I didn't make the primary ports perfectly clean (but most all the goo is actually gone; this engine had 132,000+ miles on it).
![Image]()
Here's the cleaned shaft and little parts, ready for reassembly.
![Image]()
The fun begins with reinserting the common shaft, after lubing it and the holes for it using very high temperature grease.
![Image]()
The shaft will push through most of the grease:
![Image]()
So wipe out the excess:
![Image]()
Then reinstall the discs, making sure they face the original direction. They do not fit tightly on the shaft, so make sure to center each one carefully before final tightening. You might want to use threadlocker -- I didn't, but did tighten the screws greatly.
![Image]()
Probably not necessary, but I also lubed the contact points from the actuator to the shaft before reinstalling the actuator:
![Image]()
And here's the finished IMRC going back on the SPI. Be sure you have the correct gaskets!
![Image]()
Now hit the road and enjoy restored SPI performance. [thumb]
The Intake Manifold Runner Control is an assembly that goes between the intake manifold and the cylinder head. V-8 Fords have two of them, but the SPI only has one. The IMRC is removed typically when removing the cylinder head, but can be rebuilt separately. I read that a common failure is of the IMRC's electric actuator, and I suspect some of these failures are because the internal parts are gooed up and making the actuator work too hard.
The IMRC is a butterfly valve assembly that opens under hard acceleration, for example. They are quite similar in principle to the secondaries on carburetors, and as with them, fuel economy likely is traded off for performance. If the IMRC sticks open, closed, or part way, or is sluggish to respond, both performance and MPG would be affected, IMHO.
Here's the IMRC assembly that came off the SPI I just finished rebuilding. The standard-size ball peen hammer is there for scale, not use!
Here's a close-up of one pair of "Split Port Induction" (SPI) ports in the IMRC, serving one cylinder. On the left is the normal-driving port with the hole at the top where the fuel injector shoots in the metered fuel. The other "secondary" port has the round butterfly throttle plate (technically a "damper", not a "valve"), and as you can see was heavily gooed with nasty black, oily stuff. The primary port also had this goo on its walls.
After getting the IMRC off the car, my next step was to remove the actuator. It's a sealed device unless you want to drill out the plastic rivets; this one hopefully works fine so I left it alone. I've read elsewhere that a OBD-II code will be thrown, and the Check Engine Light (CEL) will illuminate, if the actuator goes bad; this one didn't.
Next the throttle plates come out -- this was the most worrisome part because, from experience, it is easy to strip the little screws holding throttle plates on their shaft. I went through about seven of my Phillips screwdrivers until I found one that fit really well. Each screw was very tight, but came loose. Don't lose them! And note the position of the discs -- each of mine had a "Y" stamped on their top, and faced the opposite direction of the corroded/white-ish center "inverted tee" portion of the mating surface.
Next I carefully scraped the two mating surfaces of the IMRC's body -- they are fairly soft aluminum alloy and you definitely do not want to scratch their mating surfaces. Newbies should not use a steel gasket scraper like me, but I'm an old hand at this.
Next is the nastiest work, by far. Expect to use an entire can of carb cleaner -- read and follow directions! E.g., safety glasses, lots of ventilation (so do outdoors), fire precautions, etc. A couple of old toothbrushes (first one stiff, second one soft), some plastic scrapers, and rags were needed, as was a doubled, thick, large sheet of cardboard to catch the goo.
But be sure not to spray, get wet, or scrub the bearing/seal where the common shaft exits the assembly! You don't want to replace it unless necessary. The other end is sealed, and the bearings inbetween are just bore holes. At this point, don't even try to remove the shaft.
I separately soaked the throttle plates and their screws in a steel can. Then took them out and scraped/wiped the plates and screws, then repeated.
After the first pass at cleaning the body using carb cleaner and the first toothbrush, the common shaft then easily pulled out of the assembly. Here it is; handle/clean it carefully -- you don't want to bend it at all.
After lots more carb cleaner, etc., and a final washing with Dawn dishwashing liquid and water, and drying with compressed air and time, here what the body looked like. I wanted the secondary ports, and the fuel injectors' holes to be near-pristine, but for the sake of time I didn't make the primary ports perfectly clean (but most all the goo is actually gone; this engine had 132,000+ miles on it).
Here's the cleaned shaft and little parts, ready for reassembly.
The fun begins with reinserting the common shaft, after lubing it and the holes for it using very high temperature grease.
The shaft will push through most of the grease:
So wipe out the excess:
Then reinstall the discs, making sure they face the original direction. They do not fit tightly on the shaft, so make sure to center each one carefully before final tightening. You might want to use threadlocker -- I didn't, but did tighten the screws greatly.
Probably not necessary, but I also lubed the contact points from the actuator to the shaft before reinstalling the actuator:
And here's the finished IMRC going back on the SPI. Be sure you have the correct gaskets!
Now hit the road and enjoy restored SPI performance. [thumb]
