Driver, yes and no. All that the IMRC does is open the secondaries that is correct... but at the same time, the CEL and improperly working engine component directly related to airflow totaly changes the way that the computer works. It is no longer in closed loop mode, it runs in open loop (default pre-set fuel tables... limp mode) due to the problem. This directly effects the a/f ratio (which the cats are VERY reliant on being in the proper range to operate normally - hence the egg smell) which directly effects the gas milage.

I pinned my secondaries open due to the SEVERE lack of performance. The car was a total slug when they were stuck shut and I couldn't live driving the car that way, so I pinned them open which made my idle a little iratic at times and gave me big time part throttle issues before the engine reached normal operating temp. Once the car reached normal operating temp, the idle and part throttle were fine (although I was still lacking on torque due to them being open and also the car being in open loop and the a/f being way off and robbing me of power down low), but up top was lean as hell and the car would detonate under heavy accelleration at times and would ALWAYS smell like rotten eggs after getting on it or while getting on the freeway. Me pinning the secondaries totaly threw gas milage out of the window because the car wasn't running right.

A dead sign of "bad cats" is that the car doesn't move down the road hardly at all due to being clogged and snuffing the engine. When your exhaust smells wrong one way or another (like rotten eggs or whatever), it simply means that something is not right with the a/f ratio for one reason or another... common problems are vacuum leak, something like a bad injector, so on. Things like that make your exhaust smell bad.

In my case, it happened to be the fact that I pinned my secondaries open and the computer wasn't compinsating the a/f ratio normally anymore and I had all of those problems. That is why it cured so many things for me.

My secondaries were stuck closed. Had no check engine light, lost power at high RPMs, and got better gas mileage. At low RPMs, the car ran fine.

Same with mine, but the car was a total dog above 4k it was pointless and below 4k there is no power to begin with, so I had to do something. Till I replaced the IMRC, I pinned the secondaries open... there were some side effects, but worth it for having at least most of the power above 4k.

I am not sure why you didn't have a CEL saying that it wasn't working right, I sure did... not that I needed one telling me that something wasn't right, but I sure had one.

So sounds like it works like this:

- if you have secondary problem and your computer knows it you will get overall horrible performance / driveability due to default programming.

- if you have secondary problem and your computer does not know it then you will simply have less > 4k power and possibly better mileage depending on how you normally drive.

Well... on the electronically controlled IMRC's, your computer knows when they don't work. You get substantially poorer performance weather you pin them or not when they fail, or even if you pin them open all of the time because the computer goes into default mode and doesn't compensate the fuel curve properly. I can't speak for the vacuum controlled IMRC's though, I just don't know.

I know this thread is old, but does anyone have the pictures from this post around? Would be very helpful!

Originally posted by Tater Salad:

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Originally posted by Stevers:

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It's probably just a fux0red cable like mine was. I rigged up a bicycle brake cable as a replacement, and it's worked perfectly ever since (1 month ago). No way in hell was I about to drop ~150 for a new box, when a cable only put me out $3.99.

In this picture, you can see the tip of the cable (it's a small silver tip shown next to the lower PCV feed hose) that I replaced with a bolt after feeding the new cable through, and using one of it's ends inside the box itself.

The way I made the end up was to drill a small hole in the head of a bolt, so that the other end came out right where the threads started. Then I pulled the cable through and used a washer+nut to crimp it tight.

Here is a shotty picture of said bolt. It took about 6 times before I had it crimped at the perfect length where it would open them fully, and allow the cable to return enough as to not trip the switch inside the box which tells if they are in an open or closed position.

The end I was speaking of which will be left on the new cable can be clearly seen in this picture on the right side. The cable frayed itself and then finally snapped about 3" past it's exit point from the IMRC box.

Words of caution do NOT remove the PCB from the IMRC box without the connector at the same time. These pieces are soldered together, and you'll seriously bollix it up if the pins snap on either. I scraped off as much adhesive as possible from the connector area and used some slip joint pliers to wiggle the connector out. Don't be afraid to mangle this connector a little bit, but not so much as that the wires will not fit back onto it.

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