Code P401 - low egr flow
I tested the sensor with a meter good, tested egr valve; opened with barely any presure
found an article about clogged egr ports into the
thottle body.
took off 4 bolts to trottle body and to be sure the two ports
were so clogged with carbon that it actually formed a cone coming out of the hole, shaved flat then used a dry wall screw to work away the middle and then brushes and trottle body claer to get the rest.
No more hesitation, idle down below 700 and smooth
before cleaning major hesitation causing tranny to jump in and out of overdrive and rough idle with blips like it might stall
cleared code, running fine ever since

1997 f150 4x4 4.6 140k miles

knarf

 

Where did you get the new gaskets or are there no gaskets to replace?

I have been thinking of tearing into mine to see if it is getting clogged up.

 

The original gaskettes on the in-take are typically made from highly durable silicon/rubber or fiber and seldom need to be replaced (I've never seen one in bad enough shape to warrant replacement).

The EGR valve gaskette can be found at most auto parts stores for $2-$3.

The EGR ports can get clogged in as little as 30K miles or go for more than 150K with no problems. I would guess low quality fuels and/or high ambient humidity would cause them to clog sooner.

 

lateofphilly,

Where did you find the article?

Sean