Ok guys, could really use some help here. This is what I have going on......1997 F150 4.2L. Keeps throwing codes for the IMRC runners stuck open. This vehicle runs but sounds like it has a miss. IF I turn on the air or put the engine under a load, it gets MUCH MUCH worse. There is also a code for the DPFE Sensor as well.


The truck has new upper and lower intake manifold gaskets, new IMRC Control Solenoids (Standard), new linkage bushings, new plug wires, new vacuum connectors on the vaccum lines (the 3/8 lines for the breather grommet on the driver side and the PCV system on the passenger side), plugs have been checked and are good, has new exhaust manifolds, new EGR Tube and connector on the Passenger manifold, new thermostat, new cam position sensor connector (Old one cracked and went to pieces), cam position sensor has been timed with the correct OTC tool. The original IMRC solenoids were cracked and the runners were not moving smoothly. Lower intake manifold was removed and upper AND lower intake manifolds were soaked in Acetone for a couple of weeks to remove all the oil/carbon deposits, then they were both pressure washed and cleaned. Had to pull the L cylinder head due to one of the lower intake manifold bolts breaking off almost flush with the head. Head was also soaked in Acetone then pressure washed. Fuel injectors have all new O-rings. EVERY gasket that was removed was replaced with a new gasket, and everything torqued to specs (except exhaust manifolds).

So, I cleared the codes with my Zeus+ scan tool. Truck runs rough. Checked it again using Forscan, and was able to run the KOER test. Test showed both IMRC runners stuck open and a possible defective DPFE sensor. These codes were also present AFTER I cleared them with the Zeus. The check engine light was off, and the Zeus showed NO diagnostic codes present. The check engine light DID come on though as soon as I put the truck into reverse to test drive it.

I have read through some of the posts on here, and this engine has the aluminum plenum so no isolator bolts. I have checked top and bottom for vacuum leaks. Even pressure washed the engine WITH it running, spraying the engine top to bottom. NO change in how the engine runs.

Now, to me, it seems like there is vacuum going to the solenoids that is keeping the runners open, creating a lean condition (oh, and that is ANOTHER code that is present). Trying to determine EXACTLY how this system works. And is there a way to check this or possibly bypass it? Also saw mention of an IRMC Module? Where would this module be located and how do I test it? Can anyone provide any diagnostic information to help me troubleshoot this? Obviously I can't get to the solenoids to check them and to check the wire connections due to the lack of space between the engine and the firewall. So I am open to suggestions. This truck was running fine, then started getting worse and worse. During disassembly I found the IMRC runners were sticking and sluggish (did not move smoothly at all) and that the solenoids were damaged. So that snowballed into this current mess. Pulling the upper intake to find that the runners were sluggish, so then pulled the lower intake to clean it, which led to the broken bolt in the head......and so forth....now the engine is reassembled. And STILL running rough.

ANY IDEAS GUYS???? I have never fooled with one of these engines with the IMRC's. Heard they were a nightmare. Now I understand why. I purposely ordered the IMRC's in the Standard brand so I wouldn't have any problems with them. Now I am wondering if that is where the problem is?