So I've noticed a few things over the last couple months:

1. Anytime someone asks about pinning their secondaries, removing the butterflies, etc. the response is an onslaught of "Don't do it," "Your car needs it," "Removing it hurts performance" etc.. posts.

2. Many of the fastest, most tuned Contiques, are not using their IMRC's.

3. The same people telling others not to remove the IMRC are the owners of the cars with the IMRC removed.

4. The biggest reasons not to remove the IMRC/pin secondaries is that the computer will throw a CEL if the IMRC is gone and/or the air/fuel ratio will be wrong with the secondaries open all the time, causing lean conditions.


My questions:

1. Are the cars with the IMRC's removed all running full 3.0 oval port conversions, making the IMRC usless?

2. If it is indeed fully possible to rig a circuit to prevent a CEL while also preventing a lean condition, why not post a HOW-TO so that others can read what it takes and make the descion as to whether they want to risk screwing something up?

3. Is the solution to removing the IMRC getting an aftermarket chip and having it programmed to negate the computer's belief that an IMRC exists on the car?

People are not removing secondaries on oval port 3.0Ls, because they were never there to begin with. Secondaries were only used on the split port engines. I believe the only way to remove the secondaries without throwing a cel, is to just remove the secondary plates and leave the shafts in the lim. Is a couple hp gain, worth the tq loss? Not in my book.

Originally posted by beyondloadedSE:

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1. People are not removing secondaries on oval port 3.0Ls, because they were never there to begin with.
Secondaries were only used on the split port engines.

2. I believe the only way to remove the secondaries without throwing a cel, is to just remove the secondary plates and leave the shafts in the lim.

3. Is a couple hp gain, worth the tq loss? Not in my book.

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1. Your wording or perhaps thinking is incorrect.

Just because you are using oval port heads doesn't mean you do not have secondaries because it has nothing to do with the LIM.

The butterflies are in the LIM and not the heads.

There are several folks running secondaries with their full oval port 3L's.
Then for that matter I ran my 2.5L without secondaries but that's a completely different story.

2. Why would you leave the shafts installed???
That's defeating one of the major benefits. Removing that restriction! (yes there are several benefits)

You remove everything. Then rig the IMRC with a return spring. Your IMRC is still prone to heat failure though. Also if you change the IMRC point you will decrease it's life expectancy because it will be "running" longer.

3. "Properly Tuned" the loss is not that great and the gains are well worth it since they come from 3000rpm on up and get better the higher you rev the engine.
Your main loss is below 2500rpm. Nobody drives below that anyway right.


Now getting it properly tuned is by far the hardest point. IMO if you can't self tune then don't bother. Now if you need a custom chip anyway then it's a better proposition.
However while you should get WOT decent with $$$ on the dyno you won't get regular driving, idle, part throttle, et cetera.

Either way a chip is a MUST if you remove the secondaries. Without it you won't get any significant timing increase. I have a break down on my site.

Matter of fact I have all this information and more in great detail on my website!