'96 Accord, VTEC, auto, 146k. Car was running good, no serious issues, mileage isn't what I was expecting (25 MPG on a long freeway trip), but anyway. I was passing slower traffic on a two lane, needed a little more speed to pass, stepped into the throttle a little harder, she downshifted into second and began missing, sputtering and slowing down. I thought it was going to die right there. It continued running but is running REALLY rough. The codes are O2 heater circuit (I knew about that), but the new ones are P303 and P304 (cylinders 3 and 4 misfiring), and a P1300 (Multiple Cylinder Misfire Detected). I reset the codes, still rough. Pulled out the plugs, grounded them and checked them on their respective ignition wires, they were both firing fine. Have no clue what to look at next. Thank You

 

My moms Acura MDX just had this same issue and apparently a valve adjustment was needed... this is on the J35 V6 motor though.

 

It came suddenly when I was trying to pass another car and needed more speed. Other things it is doing, when it is cold, it takes about a mile of driving before it will go over 30 MPH. Also when cold, to get it to upshift into 3 and 4, I need to lift off the throttle like it was a stick. When I lift it upshifts. At highway speeds, it occasionally jerks. Need some good advice on this one. Oh yea, it DOES have a brand new timing belt.

 

Anyone have any ideas on what is causing this issue? It came on suddenly, when the engine was in higher rev's, so I do not think it is valve adjustment.

 

Found the problem, the timing belt had jumped a tooth. Why would a new timing belt with only a few hundred miles on jump a tooth? How much play is allowable? I have nearly an inch play on the rear side.

 

You may not have the timing belt (TB) tensioner engaged correctly on the pivot stud on the oil pump cover. This would prevent proper TB tensioning and perhaps allow TB to jump a lug. Most likely reason is the TB was misinstalled one lug off. Be glad it's not worse (bent valves), and make sure of TB alignment, TB tensioner installation, and correct belt tension adjustment procedure.

The 94-97 Accord shop manual from Online Manuals DIY post may help.

good luck