A quick scan showed all the Oxygen sensors, MAF Sensor and the Fuel Evap-Valve were bad. Then the engine went into safe mode and would't go over 2200 RPM. The engine would buck and stutter like a new driver learning to drive car with a standard tranny.
I replaced the MAF Sensor but the hesitation came back a few days later. A quick review by the Nissan techs found a bad connection at the Evap-Valve but nothing else. The other codes were all false. The tech had the scanner connected to the gang plug under the dash at first but he then decided to connect directly to the ECU. He was blown away by what he found!
It turns out the ECU is located in such a crappy position, below the exterior plastic cowling for the cold air intake for the heating system, that it comes into contact with washer fluid and water that drips off the windshield. The warranty period for the Quest was recently extended to 5 years and 100, 000km in Canada so if you have a 2004-2007 Quest, you might want to take some time and check your own ECU. Mine was covered under Warranty, which expires April 30, 2009! Glad we caught it before the warranty expired. 
PS the ECU's are around $1000.00 cdn plus labour to replace....
Post Title: Re: 2004 Nissan Quest - Important message to CHECK YOUR ECU Housing. (Big-Bird)
Posted by: Rockford at 10:45 AM 5/15/2009
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