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IMRC help

S

Synister6

New CEG'er
Joined
Feb 13, 2007
Messages
21
Location
Fredericton NB
Hello, I was registered on here before but couldn't find my username/password so had to start another one.

Like others, I've recieved the P1518 IMRC stuck open code, now I have searched the board and gotten some advice on how to fix it, but what I"m wondering is what causes it to stick open? Does it mechanically fail open? or does it mechanically fail closed? I guess I'm trying to narrow down my search when I eventually am able to get under the hood.

I'm hoping for a broken cable or something simple and inexpense as money is tight as I'm sure it is for everyone.

I have a 98 2.5L V6 with 106000 kms
 
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I guess I"m just trying to learn more about how the systme works so I can think through diagnosing it. I'm hesitant to apply other fixes until I know for sure where the problem is.

Thanks...
 
Synister6 said:
Does it mechanically fail open? or does it mechanically fail closed? I guess I'm trying to narrow down my search when I eventually am able to get under the hood.

I'm hoping for a broken cable or something simple and inexpense as money is tight as I'm sure it is for everyone.
Click to expand...

There's a spring on the linkage which forces the system closed. There really is no cheap fix unless the linkage connecting the 2 sides together has fallen out of the little plastic bushings. Then you can simply replace the offending bushing(s). Otherwise, you'll need to get a new/used control box.
 
Your IMRC is the silver square box at the front of the engine bay (underneath the "Duratec" plastic cover) it is controlled electronically by the PCM to actuate at either ~3200 WOT, or ~3750 any other time. When actuated, the attached cable that comes out of the drivers side of the IMRC box is pulled tight (much like a bicycle brake cable) and in return pulls on a spring loaded swivel-rod with plates on it. Those plates block half of the intake paths in to the engine, and swing open to allow air in those pathways.

There are actually two rods. The first one is physically connected to the cable from the IMRC, and is the firewall side bank. The second is the radiator side bank, and is connected to the FIRST BANK via a small "jumper" rod, copper in color, so that when one bank moves, it actually pulls the second bank open as well.

If you look directly underneath your Throttle Body you and slightly forward to the car, you will see the copper rod (if it is still there! lol) Note that there are a few reasons for your code:
Electronic failure, mechanical binding, or failure, or wiring HARNESS problems between the IMRC and the PCM itself.

For more information, you can see pictures of the IMRC rods, etc, in the UIM/LIM rebuild how-to, located in the Duratec Maintenance Forum, under the thread "read first"
 
I was having the same problem, too. I'd get a 1518 within 5 seconds of really getting on the gas at highway speeds. Then, when I would pull over to see if the runners were stuck open- they weren't :shrug: . The linkage (referred to in previous post) was fine, and I could rev the engine from the throttle body and physically SEE the 2ndaries opening :crazy: .

The problem ended up being the transistor in the IMPC box was fried. I replaced it and I swear, my car has never run better. The 1518 was likely forcing the PCM to go into "limp" mode- mind you, I was getting this code for about 5 mos. before I fixed it.

If your linkage seems to be working, try a search (on the old forums, too) for "transistor how-to" or "hightower transistor" or "IMRC transistor".
 
The above mentioned how-to fix is ALSO in the Duratec Maintenance forum "Read first" thread.
 
Welp, after taking it apart it seems like the IMRC works fine :S The P1518 code isn't even there anymore :S

Although I have some new onces, but I'm wondering if cleaning the MAF maybe did something, so I cleared all the codes, gonna cross my fingers and hope for the best and see what pops back up the next few days :S

Thanks for the help guys, very helpful!
 
Synister6 said:
Welp, after taking it apart it seems like the IMRC works fine :S The P1518 code isn't even there anymore :S
..!
Click to expand...
Maybe it is about to fail. You should consider relocating it before it does or just get ready to change the transistor or IMRC when it does. ;)
 
Synister6 said:
Relocating it? I'm not sure, well 60km since I cleared the codes adn no CEL yet :shrug:
Click to expand...
If you are asking for clarification, the IMRC breaks down due to the heat from the engine. Some have relocated the IMRC to the battery area. As for the 60Km, no CEL, if it is intermittent, well, sometimes it can go very long before the CEL comes on again or maybe it has not run the OBDII cycle yet (or maybe it was a fluke and it really is fine). :shrug:
 
Tony2005 said:
If you are asking for clarification, the IMRC breaks down due to the heat from the engine. Some have relocated the IMRC to the battery area. As for the 60Km, no CEL, if it is intermittent, well, sometimes it can go very long before the CEL comes on again or maybe it has not run the OBDII cycle yet (or maybe it was a fluke and it really is fine). :shrug:
Click to expand...

Yup, that's about as confused as I feel... One thing I noticed when playing around was that behind the throttlebody the intake looks quite oiley/grimey. I had the intake cleaned a few months ago which I would have thought would have cleaned it all out...

Not sure if it helps or not, but since you seem much more knowledgeable than me, I've been getting various P0401 (EGR insuf) and P0172/175 codes for lean before the P1518 code. Think there could be any one thing causing this array of issues?

edit, btw heat breakdown shouldn't be an issue for me here this time of year, here in NB canada is has been around -20 deg C for a month now :(
 
Tony2005 said:
If you are asking for clarification, the IMRC breaks down due to the heat from the engine.
Click to expand...

This statement is partially correct. Electronics (there's a printed circuit board inside the IMRC box) get very unhappy and become failure prone with vibration AND heat. So locating the IMRC box on top of the valve cover assures that it will see both.

Easiest preventative measure is to remove the plastic cover or cut a ventilating hole in it. Then add 3 rubber spacers between the box and the valve cover. On mine, I also attached 2 small heat sinks to the top cover acquired from an electronics store. It's been good ever since. Relocating the box is more difficult, but not impossible, due to the shortage of space in the engine compartment.
 
Synister6 said:
....One thing I noticed when playing around was that behind the throttlebody the intake looks quite oiley/grimey. I had the intake cleaned a few months ago which I would have thought would have cleaned it all out...
...... I've been getting various P0401 (EGR insuf) and P0172/175 codes for lean before the P1518 code. Think there could be any one thing causing this array of issues?
....
Click to expand...
Take care of the TB first. That would probably solve the P0401 and "rich" P0172/P0175 codes.
 
TourEnvy said:
I like you idea about the spacers and the heatsinks, how do the heatsinks attach?
Click to expand...


I removed the cover, then drilled 2 holes per heat sink (cover too), tapped the holes in the heat sinks for 10-32, got some heat conducting compound from the electronics supplier when I got the sinks, applied it to the sinks and used Loctite on the threads.

I'll take a digipic and post for you.
 
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I forgot to say Thanks to everyone for helping me diagnose this problem, luckily nothing seems wrong and 500km later still no CEL (knock on wood)

So, Thanks again for pointing me in the right direction, much appreciated!
 
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