[mxu63]

I recently got SES light on and I purchased a OBD II reader and found out the DTC P1518 (IMRC Stuck Open).

But, after opened up upper intake manifold I found out that no runners appear to stuck in opened. Each pair of runners have one open and one close. The following photos for two pairs of runners on firewall side, one left side and one right side from driver's point of view.
http://www.flickr.com/photos/xumba/4939794740/
http://www.flickr.com/photos/xumba/4939794406/in/photostream/

Looks like the runners are fine unless I am mistaking what the runners are. Although the carbon buildup is pretty bad.
So, what is next? the controller and related cable? Blind Seafoaming?

 

[KhanTyranitar]

With that code stuck open, it means that the computer is not getting any feedback from the actuator. I'm not 100% sure about how this works, so call this an educated guess, but I think the IMRC can tell the computer how far it is open, probably through an internal sensor. My guess is that has gone wrong so the computer thinks it is open all the time.

I would clean the butterflys anyway.

 

[shoz123]

Either the butterflys are being help open a tiny bit or the plastic gears inside the IRMC box are damaged. There is a tiny micro switch that needs to be made inside the box to keep the light from coming on.

 

[mxu63]

Thanks guys. I will open up the IMRC. It seems sealed. Do I need to use some kind of sealant when close it up? I really don't see the point of it.

Oh, one more thing, after engine shut down, the cable from the box to engine seems very loss. is it normal?

 

[KhanTyranitar]

The IMRC allows the intake velocity to remain high at both low RPM, without being restrictive at high RPM. If the butterflys are open all the time or weren't there at all, there would be a decrease in low end torque and fuel economy. The device is actually quite simple, and allows the best of both worlds.

 

[mxu63]

I opened up IMRC. Everything look just fine except minor black oily stuff. I cleaned them.

What I found interesting is that PCM is actually instructing IMRC to open up bufferflies even at relatively low RPM (far before 3000). It either believes RPM reached 3000 or it believes not enough air intake.
The question now is that what exactly makes PCM make such wrong decision. Is it soly RPM, or other sensors directly or indirectly evaluating air intake?

Any idea please?

 

[KhanTyranitar]

The computer uses a combination of throttle position, MAF signal, and air density to decide when to open the valves.

 

[mxu63]

so it sounds like sensor errors.

 

[KhanTyranitar]

No, if it were sensor errors, you would have codes for sensor errors. It sounds like something in the IMRC system is broken.

 

[mxu63]

Khantyranitar, shed more light please. Here is my understanding:
1. PCM consolidates informations from sensors and concludes that it is time to turn on butterflies. Hance, it sends out signal to IMRC.
2. IMRC then turn on the motor that actually via few wheels pull a cable that eventually turn on butterflies in secondary air intake runners

The key here PCM sends IMRC signal too early. Why?

 

[thecurrent]

Did your scanner say if this was an active Code and how many start cycles since the code was set?
I would start with cleaning them real good, re-install and then clear the code. Maybe even D/C the battery to reset the PCM adaptives. If it comes back on immediately or after a while then you may have to replace some things.
Found this on AllData:
Cleaning and Inspection

1. The following materials are required for the cleaning procedure: a 13-25 mm (1/2-to 1-inch) wire-stemmed horse hair or nylon bottle cleaner-type brush, Ford Carburetor Tune-Up Cleaner D9AZ-19579-BA or equivalent meeting Ford specification ESR-M14P9-A, rubber gloves, and eye protection. (Do not use choke cleaner solvents.)
2. Remove lower intake manifold (IMRC).
3. Disconnect the linkage rods from the levers and plastic bushings (if equipped) and verify that the shaft assembly is causing the stick/bind/grab condition.
4. Holding the IMRC housing assemblies vertically, liberally spray the cleaner into each of the eight bores concentrating the spray at each shaft/journal interface. Spray from both the top and bottom side of the bore, rotating the shaft by hand and pushing end-to-end to work the cleaner into the journal areas. Soak assemblies for 15 minutes .
5. Saturate the cleaning brush with solvent and scrub between the bores and valve plates. Apply some pressure on the brush while scrubbing, concentrating on the area where the shaft meets the housing journal.
6. Spray cleaner on the bores, plates, and shaft as needed to wash away any residue.
7. Use shop air to blow away the remaining residue. Concentrate on blowing the residue Out of the shaft/journal area. The shaft should now rotate freely without sticking or binding.
8. NOTE: If the lower intake manifold (IMRC) has been properly cleaned following the above procedure and still does not rotate freely, replace complete lower intake manifold (IMRC). Re-install linkage rods. Use new plastic bushings (if equipped).
9. Install lower intake manifold (IMRC).

 

[mxu63]

Hi thecurrent, thanks for your detail post. but the procedures are all about cleaning up to eliminate the stuck. However, in my case, it is not the cleanness. it is the PCM decides to start the butterflies too early.

 

[thecurrent]

Just found this TSB..

Article No.
02-15-3

08/05/02
DRIVEABILITY - MALFUNCTION INDICATOR LAMP
(MIL) ILLUMINATED WITH DIAGNOSTIC TROUBLE
CODE (DTC) P1518 INTAKE MANIFOLD RUNNER
CONTROL (IMRC) - VEHICLES EQUIPPED WITH 3.0L
4V ENGINE ONLY

FORD:
1996 - 1999 TAURUS

MERCURY:
1996 - 1999 SABLE

ISSUE
Some vehicles equipped with the 3.0L 4V Duratec engine may exhibit a Malfunction Indicator Lamp (MIL) illuminated with a Diagnostic Trouble Code (DTC) P1518, Intake Manifold Runner Control (IMRC) stuck open, with no driveability concerns present. This may be caused by the calibration of the Powertrain Control Module (PCM).
ACTION
Verify condition and DTC P1518 is present. If DTC 1518 is present, check for freedom of rotational movement in the Lower Intake Manifold Plates. If the manifold plates rotate freely, reprogram the PCM. The new calibration strategy will cycle the IMRC when the vehicle speed has exceeded 40 MPH (64 KM/H) and deceleration occurs. The IMRC will cycle after every other drive cycle over 40 miles per hour. This will eliminate sludge build up in the IMRC. Refer to the following Service Procedure for details.
SERVICE PROCEDURE
1.Manually rotate the Manifold Lever Arm to verify that the Lower Intake Manifold Plates rotate freely. If plates do not move freely, refer to Workshop Manual Section 03-12 to service before continuing with this article.
a.If plates move freely, reprogram the PCM using the Worldwide Diagnostic System (WDS) or New Generation Star Tester (NGS). Refer to the PCM Calibration Information Chart shown.
b.Road test vehicle to ensure DTC 1518 has been repaired.
2.If DTC code P1518 is still present perform normal diagnostic as outlined in the appropriate PC/ED Manual and service as required.

Is the car running normal? If it is I would just clear the code and d/c the battery to reset everything and see how that goes. Had a similar code set on my 06 Mustang GT, something about the intake manifold plates. Car was running just fine, cleared codes and it never came back.

 

[mxu63]

Hi thecurrent, thank for the TSB. Great info. I did play with the leveler and it moves just fine (smooth and free, with good tension).
I did clear code. But came back.

If I go to dealer with the TSB, would I be charged for it?

 

[sheila]

I am pretty sure they will charge you for any work performed on a technical service bulletin. It is not a recall notice. I had same code on a 98 tec and manually worked the linkage at the white bushings while spraying some penetrant. Erased code and never returned. Dunno, maybe got lucky? Also make sure white bushings are in place. Good luck!

 

[sheila]

TSB acts more as an assist or guide for them.

 

[timmytaurus]

Anything more on this? My IMRC gives a p1518 code and pulsated after a cold start. Do I need a new box? I see alot of Duratecs at the Yard I go to. Getting ready to Seafoam now.

 

[sheila]

Some have reported frayed or broken cable inside the box. Others have had the white plastic linkage bushings (2) fall out or break near the manifold.

 

[sheila]

Try working the linkage back and forth by hand near the white plastic bushings (near manifold) while spraying with penetrating lube. Clear the code and see if it returns.

 

[timmytaurus]

I had same code p1518 on my 1998 v6 24v DOHC. I soaked IMRC linkage with WD40 and workked it manually a couple of times. Opened the IMRC box, but everything looked fine, resaled with $3 liguid gasket stuff to keep it dry. Sea foamed the intake. The intake has a Warning on it saying not to spray anything in it, but called Seafoam directly and they said it is okay, won't hurt it.

Disconnected the battery to let the PCM reboot fresh (It's like rebooting a home computer). Light went out and hasn't come back on.