Contour Enthusiasts Group Archives Forums Modifications Duratec Performance What are the secondaries?

What are they, how do they work and how do you know they're working ? Thanks.

they open up so your car can get more air, u know that they work after 3-4K rpm if ur car is pulling hard, if it feels weak then they are probobly not working There is alot of smart people on here they can explain it better then me.

The LIM (Lower intake manifold) is equipped with secondary butterflies. There are a series of holes going through the LIM that allow the air through it and to the engine itself.

Half of those holes are closed (covered) with a metal plate at anything below the ~3700rpm (3200 @ WOT) point. Once you reach that point, the PCM sends a signal to the IMRC (Intake manifold runner control) to open the secondaries The IMRC is located on the radiator (front of car) side of the engine, underneath the plastic cover that says "Duratec" on it. IT is a small silver square box.

When the IMRC opens the secondaries, it does so via a cable (like a bicycle brake cable) that runs out of the IMRC and down to the LIM. When pulled, the other half of the holes in the LIM open up.

When closed the engine has a smaller capacity, increasing velocity and low speed torque (when you need it most). When opened, it has higher volume of air, and aids in increasing horsepower. (Of course other things are needed, too.. like increased timing, more fuel, etc...)

You can physically tell they are working by the "surge" of power at around 3200 RPM in the lower gears.. (1st through 3rd are most noticeable) this is if you are at wide open throttle.. AT less then WOT, they will open at around 3700 or so.

You can VISUALLY verify them to be working by looking at the secondaries being opened while you rev the car past the opening point from within the engine bay. You can see the secondary linkages by following that cable from the IMRC to the LIM, and looking for a brass connecting bar (that goes from one half of the LIM to the other, allowing them to both open at the same time..) when you rev the car, the bar should move back towards the firewall, and away from the radiator...

Normally, you will also receive a CEL on the dashboard that indicates a malfunctioning IMRC. (Scan your codes at Autozone for free, just make sure to get the CODE, and not the description they tell you...)


Ray

Very informative. Thanks Ray and everyone.

well said.

Ray, not trying to be a suck-up, but you give some of the best descriptions/responses. You break stuff down into everyday language. I've seen a couple other guys do the same, ( I'm a teacher, so I notice how people expalin things.) Speaking as a newbie to the site, I want to say thanks to all the folks who reespond like this. What's that?.......I I know. I'll still search first. THanks.

getsum,

Thanks, man.. I appreciate hearing that. It makes my day when someone can read what I typed and get the message I was trying to convey. I have said it more than once: I try to write all my how-tos and faqs from a novice mechanic's perspective. I don't want all the technical jargon thrown in first..

When I first started looking in to ANY car, at all, I knew absolutely nothing about them. I would look up how-tos and I would get technical descriptions, and a lot of assumption that I knew HOW to remove the "whatever".. I didn't want someone to say "remove it", I wanted someone to say, "You need to remove that little brown thingy by turning it so that it will loosen and drop down."

I try to stay of the mindset of, "If I didn't know WHAT a tire WAS, could I still follow this how-to?" If I would have ANY trouble.. its off to rephrase, without sounding like a kindergarten teacher... Knowing that this style helps, and coming from a teacher, makes it worthwhile. Thanks.



Ray

They are the things laying in a box under the 3rd shelf from the right in my garage. Right next to the torn apart IMRC with a twin relay & rpm switch setup.

Mine is ductaped to the heatshield on my intake.
I like that ghetto style engine bay.