Ash J. Williams

2005 MDX runs rough, hunting idle. misfire codes on all banks plus random misfire code. evap monitor ready occasionally. what could this be? plugs replaced, EGR valve and passages cleaned.

Duane_in_Japan

What spark plugs are you using now and before the change. Use only OEM brand and specific heat range is the correct answer. Since you have the ability to monitor misfire, now once we have the correct spark plugs installed, you will want to monitor short and long term fuel trims, MAP voltage at idle and the O2 sensor voltages at idle and at a steady cruise.

Let us know what you find.

Ash J. Williams

i am using the cheap autozone plugs. i shall replace them with OEM equivalent. i do not have any ability to check fuel maps nor read the voltages off the sensors. i simply have an ODB2 reader. i have heard these engines are very sensitive to the spark plugs.

J_DC5

Yes they are only use OEM plugs and see which cylinder misfires first swap the coil to a different cylinder on the other bank and see if it followes .
this is the cylinder order 1 2 3
4 5 6

1.7na

How many miles on your MDX? Maybe it needs a valve adjustment. I have 95K on my 03 and also had cylinder misfire codes on all cylinders as well as rough idle until it is fully warmed (also swapped our the EGR valve thinking that was the problem) Dealer indicated that I need a valve adjustment and said it is not unusual that it will cause it to throw a code.

Ash J. Williams

It was exactly that. After checking the specs on clearance most exhaust valves were extremely tight. The adjustments cleared the issue. It is a relatively easy procedure to do as well.