sleeperblue

I have done the following to trace down the P1399 code: Replaced Coil Packs, Seafoam, injector cleaner, plugs, clean EGR port, IACV/EGR seems fine (unplugged it and the motor runs the same crappy way). My next step is to remove the Cat and check that...the exhaust smells like rotten eggs...
Symptoms: Increasing stumbling (gets worse every day), rev the motor and I hear a new noise, like a short pumping noise from the back of the engine...Any thoughts/ideas would be appreciated...

juanclopez2786

iTrader: (3)

i looked this problem up on hondas IN network hope it helps..
Misfire DTCs, Engine Runs
Rough From 40 to 70 mph
When owners of ’00–03 3.2TLs, ’01–03 3.2CLs, and
’01–02 MDXs complain about the engine running
rough between 40 and 70 mph, are you finding
misfire DTCs (P0301 thru P0306, P1399, P0133)
set? The problem could be clogged EGR ports or
an upside-down intake manifold upper cover
gasket. Since the EGR ports aren’t symmetrical, an
upside-down gasket covers some of the ports,
creating uneven EGR distribution.
To check if the upper cover gasket is correctly
installed, remove the plastic intake manifold
cover. If you see a locating tab on the gasket at the
throttle body end of the intake manifold, toward
the rear cylinder head, the gasket is installed
properly. If you don’t see this tab, the gasket is
installed upside down and must be replaced.
Remove the upper cover and the gasket, and
clean out the EGR ports. Reinstall the gasket (use
a new one if it was installed upside-down),
making sure the locating tab on the gasket faces
toward the rear cylinder head. Reinstall the upper
cover, and torque the bolts and nuts to spec.
Reinstall the intake manifold cover, and you’re
done.

MOBB

I'm kinda having the same problem upon start up the engine stumbles catches and then idles at 400 rpm then when I hit gas to get it up I can hear Popping noises from the engine kind of like a backfire, after 2min of letting it idle it goes back to normal.

sleeperblue

Checked the Intake Manifold cover gasket, on right, looks straight and clean.
Pulled all the plugs, all appear to be firing the same, Clean at the tip, black soot below. Still stumbling. Disconnected the IACV (attached below the TB) and the engine RPM rises and falls, connect it and the Idle stabilizes.
I'm thinking maybe another can of seafoam? Or replace O2 sensors?

thanks for the past posts...any other ideas?

juanclopez2786

iTrader: (3)

to be honest it could be a few different things. i worked at a honda dealer for 3 years and i seen all types of crazy things. id start by checking compression making sure no valves are bent cuz ive seen that before, but that'd be very rare. has it ever overheated? could be headgasket.... also check injectors could have clogged injectors. i wouldnt replace parts as a guess its a waste of money. id aim more towards injectors tho because ive seen alot go bad on hondas. if you lived in jersey id say i could definately help you out with diagnosing it... hope this helps you a little more..

Acuratec

hi i think you should check the egr lift sensor voltage at idle it should be 1.10 no more if it dose replace it i seen stuck open EGR also by now with the missfire you have you the cat is gone it melt becuase to rich.