IM fed up with the IMRC!

[wild01ride]

OK, I've read volumes about IMRC problems, solutions and stories and about a month ago I got a service engine light and lo and behold, no roar at 3400RPM.
All opinions aside, I tore apart the box and decided to replace it (cable shredded all to ****!, etc.)
So, I installed a brand new IMRC module today. Started the car- no MIL! Good news. Putted out of the sub and took the long way to the main roads to let 'er warm up (we're talking cold a$$ Michigan here!) Stopped at a light. From a stop, I moderately accelerated through 3400 on to about 4500 at most. However, I heard only a faint hint of change at 3400. I stepped a little harder at the next light and, although the acceleration was much better than my recent SLO performance, I still didn't hear the howl.
Here is my scenario and question: About three months ago I installed a K&N cone. I had never noticed the secondary howl before, but ever since I have had a substantial howl at 3400 and up. If someone could describe the howl that they are accustomed to I would appreciate it, because the howl that I have had has been very noticeable and loud to the point where it is almost annoying at some points. The sound was mean under heavy throttle, but say, cruising down the highway and tipping in enough to get the converter to unlock but not enough to get a downshift would produce a droning that was just at the pitch so that you couldn't talk to someone in the car.
Here's my hopeful philosophy: Since my IMRC had been on its last leg (and the cable was frayed down to about the last three out of fifteen or so wires), I'm thinking that when the IMRC was actuating the butterflies it was only opening them part way which produced a lot of resonance due to the butterflies acting like a reed in an instrument rather than opening full.
I would really appreciate input from anyone else concerning this issue. Also, please explain the characteristic howl that you hear (intensity, etc.) so that I can judge what I'm experiencing.
Thanks a bunch!

 

[stephen newberg]

I must admit, I have always been curious about this supposed howl over 3400 rpm also. Like you, I do not get it (and never have), and also like you, I get very substantial acceleration coming on at about that rpm. Plus, the one time I took the car to the track, I was running low 15s, and the car still pushed you back into the seat about at that point, so obviously the secondaries are working properly.

My intake is just a modifed form of Porter with a single section of flexible truck rad hose from the airbox to the inner wheel well.

So, you are not the only one not hearing any roar. I like your explaination, but I have no idea if it is correct or not.

Other views?

pax, smn

 

[SHOZ123]

I hear it, most noticeably in 3rd gear at at least 3/4 throttle. More than likely the IRM butterflies are carboned up so bad they aren't opening or hang up. Got to be some reason for fraying the cable.

 

[TitoElSpicco]

<-- noob

I've done a search but can't figure out..

what does IMRC actually stand for?

 

[SHOZ123]

Intake Runner Manifold Control. This, on the V8 and V6 Duratec motor is an electrically operated cable that will pull the Secondary intake runners open.

 

[SHO#7]

I too have a K&N Cone filter. And I have lots of noise. It sounds good in my opinion, but I do not drive her often.

However, even with the noise. I have a good IMRC and cable, and with the recent cam weld and having the intake all cleaned out. And no codes about IMRC not fully opening, or not fully closed. I do not know why yours is not loud. I personally like the sound.

Although with a tip from Paul, I need to get a little more cold air up there, as sucking all that warm air most likley hurts more than helps.

Good Luck

 

[wild01ride]

To get a little extra cold air to the cone, I cut the saxocone tubing just forward of where the system bends forward towards the air dam (under the wheel well) Basically, I left just the 90 degree bend where the tubing comes out of the saxocone tube and bends forward. After removing the internal baffle in the saxocone, I have hopes that at least some fresh air makes its way to the cone. I took the air box out completely but left the tube that come out the bottom to route the air in from the remaining saxocone system. This left a nice little rest for the tip of the cone and I also cut a little channel into it and mounted the IAT sensor there- pretty trick looking actually!

 

[98shotoy]

When I bought my Sho I had a bad IMRC so I didnt know what kinda power or noise I was mising out on. Then I got her fixed and noticed a big difference as far as noise.

Here is an easy way to hear the secondaries open up if you do not have an open cone filter......

Just take the panel filter out of the factory air box and then take it for a quick drive down the street. Once you open the secondaries you WILL noticed the sound difference...hence you have a functional IMRC. You will not hear much of a difference with the stock filter in the car OR a K&N Panel Filter. You either have to have an open cone filter or take the filter out to hear it. I also would NOT advise driving around without the fiter in the car....I only say to take it out in order to hear the sound it makes when you open he secondaries.
To best describe the sound...it sounds like your exhaust has a small hole in it...with a rumble. I LOVE the sound it makes thumb

 

[DavidT]

Stephen, Are you using a 3" hose?
Just curious because I got some 3" dryer duct and will possibly put it in. When I took a hacksaw to my saxacone (leaving only the top piece that connects to the airbox and about 3 inches of it inside the fenderwell) I never did hear the secondary roar. Then I took the last piece out (leaving NOTHING connecting to the hole at the airbox)... and lets just say it adds a whole other dimension to driving the v8 sho thumb
I am wondering if I connect the 3 inch dryer duct (to draw in some cooler air) if that will silence the 3400 rpm roar?

 

[stephen newberg]

Yes, I used 3" diameter rubber hose that would normally be for a truck rad. It is strong and has a smooth interior, plus it flexes to the size for the cut out into the inner wheel well.

My only concern with using the old dryer ducting you mention would be if it has ribs. The idea is to get a very smooth, constant air flow, which would be somewhat defeated by ribbed tubing or using the elbow that is part of the normal Porter system.

You could be right about why I do not hear any real extra 'roar' out of the secondaries. The sound could easily be getting trapped in the inner wheel well. My sax is completely removed and in the trash years ago. I cut off the connection at the air box, leaving just enough to use as a lip to attach the rad hose and it then goes as a straight line to the cut out to the inner wheel well. Never tried running it with it off.

pax, smn

 

[SHOZ123]

Whereas the internal spiral ribs on the hose will cause a narrowing of laminar flow, i wouldn'tr worry too much about it. After the duct the air needs to take a sharp turn into and then through the air filter. You can get relatively smooth expandable 3" aluminum duct. Take it and some good black electrical tape. Cut the duct to about 2' without expanding it and connect to the air box lid with the tape. Wrap the entire duct with the tape. Then insert into the fender opening and clamp the lid on. Much easier than any plastic elbow and lighter weight too.