Exhaust entering cabin while under acceleration or under load. The exhaust entered cabin especially when the HVAC system was in "recirc" the dealer and Acura were unable to find the problem after multiple visits. I documented that carbon monoxide was building up inside to alarming levels using a real-time industrial gas detector levels exceeding 160ppm while pulling a ~3000 lbs boat on the interstate with a slight head wind. (being measured from front seat/ I have video recordings of this and other documentation showing the buildup after normal acceleration entering interstate etc. The actual problem was discovered when I personally was inspecting the vehicle and found both rear body plugs missing. They are at the rear of the vehicle one on each side that leads to the interior or the vehicle. Once pointed out to the dealer they were embarrassed and fixed immediately. The plugs were loose fitting so they glued them in. The issue now seems to be resolved. I have noticed several other internet postings with similar issues. It is a safety issue in my mind because of the co if your driving normally against the wind and the HVAC is in "recirc" the levels will build up >35ppm especially in high winds or higher altitudes and you can't smell it. Clips that illustrate hole youtu.be/srpukaxv83O youtu.be/1I0aun8vt4S parts to replace body plugs grommet, side panel - 2010 Acura MDX (74514-stx-A00) item 9 on the diagram www.acurapartsnow.com/parts-C...per/grommet-rr thread that allowed me to find real problem (beginning and end is the relevant sections) MDX.acurazine.com/forums/showthread.php?T=867878.

- Mcpherson, KS, USA