I wanted to add these pics to somebody's thread, but couldn't find one so.... if you wonder what it looks like inside here goes..... I replaced this a year ago to clear my P0401 with the blue top modulator. You can see the damaged diaphram. Also added a pic of the VSV for the egr.
I am glad you posted the pic of the modulator. It shows how when the modulator goes bad, it lets carbon into the vacuum system, thus the carbon plugs the VSV.
I am on my second modulator and VSV.
The first one went bad at around 200,000 miles.
The second one was replaced around 270,000 miles. I did not test the second pair but a Toyota dealer did as I had no place to test them but it did clear the CE light and lowered emissions.
My theory back when mine went bad years ago is that the modulator diaphragm cracks and lets carbon get into the vacuum system and carbon gets stuck in the VSV. So if the one or the other goes bad you may as well replace both.
If I have to replace the VSV again, based on how often I have changed it, it will have about 550,000 mi on it...I hope to afford a newer LC before that happen. But if i still have it it will look much like this.
And yes that Turdvalanche' is part FZJ80. The top and bottom support beams are the factory running board from my 80. So this is 80 Tech and not chit chat.
Wounder if there is a way to put a filter on the vacuum line to filter out any carbon that may get into the VSV.
I am ASSUMING that its carbon that is messing up the VSV. The VSV is a tiny electric magnet with a diaphragm that opens and close the vacuum line.
Yes relocate it if you can but a filter could solve the problem.
One chunk of carbon would be enough to break the seal on the VSV diaphragm and cause a vacuum leak. If you have not taken apart the VSV and hooked up a battery to it, do so. Its neat how it just goes up and down.
Next time you replace the VSV make sure you blow out all the vacuum hoses to get any carbon stuck in there out. I would say to remove all the hoses and blow them out and inspect any of the junctions between the modulator and VSV.
Yeah I actually changed out every single vacuum hose in the truck with the engine rebuild last month. Shouldn't have an issue now for a very long time.
got my first 80 a week ago and got a P0401 today... sort of bummed already having issues not even having it that long. PO rebuilt the motor, noticed a lot of the vacuum lines weren't replaced, wish they were sine some of them do look old and starting to crack. The EGR thing looks lie it may have been replaced, will have to check w/PO on that, cleared a code to see if it was a fluke or if it'll come back again. Any say of how soon the light will come back on if EGR or VSV (which I still don't know what it is or where it is yet) are bad. Also I wonder if there could be any relationship of that code to filling up with Costco 89 octane since it happened 10 min after I put gas in it. (it does see m to just go trough gas... hard to calculate exact mpg yet)
If the diaphragm is cracked up like that and i did the egr hairpin bypass on a 94 but did not block off the egr pipe, could it cause extra air going in that eventually causes a lean code?
