EGR Modulator: is this bad? (1 Viewer)

[rolliges]

Removed the old-style (green top) EGR modulator and found a bunch is fine carbon granules under the filter.

I have the PO401 code.

Is this modulator bad?

 

[landtoy80]

Its what mine looked like when I had to replace it so replace it. I am on my second replacement modulator, they don't last forever.
You don't want that carbon getting into the VSV through the vacuum system.

 

[ToyotaDon]

The carbon could be coming from the exhaust side through a ruptured diaphragm, you need to physically check the modulator for that. It could also be coming from the vacuum side, in that case you need to make sure all your lines are clear.

 

[landtoy80]

<<<It could also be coming from the vacuum side,>>>

Where would carbon enter the vacuum system from the vacuum side?

 

[rolliges]

<<<It could also be coming from the vacuum side,>>>

Where would carbon enter the vacuum system from the vacuum side?

^^2x

Vacuum to modulator comes from throttle body. Pretty clean in there (or should be)!

 

[Funner]

i have been helping my BIL try to get rid of the same code. We pulled his modulator and it was just like yours. we cleaned it and the lines in and out. Made no difference. He then ordered and installed the new modulator again with no resolution. I think it is more a symptom of another problem. My guess is VSV.

 

[landtoy80]

Clean the temperature sensor that screws into the EGR. It gets carbon on it and "may" affect EGR operations. I clean it when I replace the VSV and modulator.

 

[ToyotaDon]

<<<It could also be coming from the vacuum side,>>>

Where would carbon enter the vacuum system from the vacuum side?

^^2x

Vacuum to modulator comes from throttle body. Pretty clean in there (or should be)!

My hard lines have been getting carbon in them. Everything works as long as they are clear, so I know the modulator I replaced last year is still good.

Theoretically, there should be no carbon in vacuum lines, unless the modulator lets exhaust gas enter them. They are also flowing the opposite direction, so should not be filling from the intake side. You guys may be right, but I know carbon does build up inside throttle bodies, mostly from the PCV system.

 

[bigredmachine]

you could always try to dissable the egr and not worry about it. i dissabled mine and the truck has run better (i think the egr valve was intermititanly getting stuck partially open), so i cant say that your truck will run anny better, but you wont have to deal with teh p0401 anymore.