thumping noise in or around plenum on 2000 Ford Windstar

constant codes po1071 and po174 changed pcv valve and line changed dpfe sensor and hoses changed egr and line cleaned maf sensor engine idle is smooth and good power no hesitation or stalling cold starts or quick and easy the thumping is not constant and tends to stop in gear. please help

by in Ravenna, OH on November 21, 2012
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2 answers 4 comments
ANSWER by , December 01, 2012
You need to change the isolator bolts, you have a leak on the intake under the plenum. This is the very most common problem on V6, 3.8L engines. They even sell these repair kits, everything you need on eBay for this problem. I did mine at 60k miles 3 years ago and been fine since. The thumping noise is hopefully a cracked/separated baffle inside the plenum. You can see if this is the problem when you do the repair above for the P0170/P0174 problem. This is also a very common problem. Mine has been doing it the last 2+ years, sounds like a diesel engine idling but tends to come and go. It is just a rattle caused by air moving over a plastic baffle that has come loose and vibrates. It can be repaired by using RTV silicone to fix it into place.
COMMENT by , March 11, 2013
I've searched on ebay and have found no repair kit for this common problem. I've even heard that they sell a one piece replacement plenum. Does anyone know where to get one of these? I am a little hesitant to put RTV sicicone in any area where it could end up clogging a sensor or worse. I would rather find the one piece unit. Any help is appreciated! Thanks in advance.
COMMENT by , March 11, 2013
Search eBay for Engine Valve Cover Repair Kit (Dorman 615-177), you will want the kits that have the valve cover, isolator bolts, all gaskets, vacuum hoses etc. Dorman also has replacement plenums and upper intake assy's listed on eBay but I have not used them nor have i fixed my "rattling" Windstar noise as of yet.
ANSWER by , November 21, 2012
this means you have bank 1 and 2 running lean poss vac leak seek diag and est
COMMENT by , November 21, 2012
yes OBD II says bank 1-2 lean can't hear or find a air leak. thumping sounds like its comming from plenum and not constant in gear it quits no loss of power or stalling
COMMENT by , November 21, 2012
poss bad intake runner. have smoke test down do determine there are any vac leaks. if there are no external leaks you may need to pull intake manifold