I drove my windstar for about 6 months before coughing up the $150 x 2 for both IMRC valves and didn't notice any problems other than the check engine light. The IMRC valves simply open and close portions of the intake manifold to regulate the speed of air rushing through their interiors. Closed valve = more air speed because of less cross-section area per unit volume of air moving. The explanation gets into physics and geometry calculations, which I'll leave out.
Realize that both IMRC valves function off of only one vacuum source, so having a leak in the diaphragm of one IMRC will cause the opposite IMRC to malfunction, too. Unplug the vacuum source to the IMRC, move the hinge, then place your finger over the vacuum vent on the IMRC. If the valve stays put, it's OK. If it moves, you found the one with the damaged diaphragm. Try rockauto. Com for IMRC replacements (mfg = dorman) instead of your local Ford dealer. Ford (at least here in S. Florida) want ! $320 ! For each. Yea. Right.
Your lean code may be set by having a dirty MAF sensor. Remove the MAF, spray some brake cleaner or similar solvent to the two MAF elements to remove any burned-on dust. Blow with shop air being careful not to apply too much air pressure to elements (don't damage them), and re-install. Monitor fuel trim values on a scanner, if possible.
I doubt the lean codes have any relevance to the IMRC's.
Tuesday, February 10th, 2009 AT 8:41 PM