Checking VSV for EGR easy way P0401 (1 Viewer)

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I own a '94 FZJ80, I recently had it serviced at Toyota and was curious if the shop could have done something to the EGR system to make my code 71/PO401 to come on? I'll explain, I had a terrible leak on the back of the engine but couldn't tell or see the location of the leak. I took the truck to Toyota and they had to replace the valve cover gasket. My question is this, would it be possible of them to have knocked something loose inside the EGR or anything else to cause this code. I've not had any engine code prior to taking it in to the professionals. Any help or idea would be appreciated.
 
I own a '94 FZJ80, I recently had it serviced at Toyota and was curious if the shop could have done something to the EGR system to make my code 71/PO401 to come on? I'll explain, I had a terrible leak on the back of the engine but couldn't tell or see the location of the leak. I took the truck to Toyota and they had to replace the valve cover gasket. My question is this, would it be possible of them to have knocked something loose inside the EGR or anything else to cause this code. I've not had any engine code prior to taking it in to the professionals. Any help or idea would be appreciated.

Sure it is possible. They may have left a wire plug or the vacuum hose disconnected. With all the ex-cons working in the auto service business, they may be trolling for more business. If you take it back, they charge you $1000 to fix the smog system and just plug it back in. I have seen this happen because I used to work in a shop full of ex-cons. It is the only job they can get where they can keep on stealing and not go back to prison.
 
Interest thing

I follow your instruction and could not get any Ohms to register. But when I reconnected the wires to the VSV and turned my engine on the CEL light went off. I wonder if it was loose or something to begin with even though I could not get it register.
 
Thanks for posting. I just checked mine and it read 35.8 ohms. I think it is good. The PO401 code just came on today and when I got home I pulled off the EGR, TB and upper intake to start cleaning everything. Hope to have it all back together next week and the code stays away.
 
For that code, the first thing you would want to do is make sure the EGR valve is not stuck open. Check for a rough or low idle and see if the idle improves when you whack the valve with the handle of a screw driver. If not, then check the valve for function by pulling a vacuum on the EGR valve actuator. It should stall or idle rough with vacuum applied and idle smoothly when you release the vacuum

I noticed that my idle became low after the PO401 code came on. Do I need to replace the EGR valve and EGR Vacuum Modulator?

Thanks
 
don't mean to necro the thread, but i just did this test on my 71 code lx450...

pulled the plug and checked continuity between my yellow wires.... nada... are there instructions on replacing the VCV? is pulling the intake a big job?

i guess so if people tend to do the PHH at the same time...
 
don't mean to necro the thread, but i just did this test on my 71 code lx450...

pulled the plug and checked continuity between my yellow wires.... nada... are there instructions on replacing the VCV? is pulling the intake a big job?

i guess so if people tend to do the PHH at the same time...

One option is to leave the old VSV in place and mount the new one outside the intake like this:
(the vacuum lines are run in series with the old VSV.)

New VSV.JPG


I just passed smog here in Cali. with no problem, didn't fail for "tampering".
 
that looks like a great idea... thanks!

also, what is the part actually called? i'm getting really confused here... looking at rock auto...
 
"VSV for EGR"

The Doorman knock-off is about $25 on Amazon, but has bad reviews. The $100 OEM part was money well spent IMO.
 
I don't know exactly how the VSV works but would lack of vacuum from a leaking vacuum hose cause the VSV fail to operate? See pic below...
20150521_085737.jpg

20150521_093818.jpg
 
Any leak in a vacuum system is bad. That hose definitely needs to be replaced.
 
Have you pulled your throttle body to see if the port from the EGR to TB is clogged? Mine was pretty bad.

Anyone have a source for good tiny brushes or port cleaners, I have also had the EGR code for years and I have replaced the EGR, VSV, all vacuum lines I could find, cleaned all ports and passages through the Plenum I could find and still the code pops up shortly after clearing... grrrrrrr. I would love to figure this mother out... I am getting really sick of the CEL staring at me all the time...
 
Anyone have a source for good tiny brushes or port cleaners, I have also had the EGR code for years and I have replaced the EGR, VSV, all vacuum lines I could find, cleaned all ports and passages through the Plenum I could find and still the code pops up shortly after clearing... grrrrrrr. I would love to figure this mother out... I am getting really sick of the CEL staring at me all the time...
ImageUploadedByIH8MUD Forum1433036476.905448.jpg

Just bypass the stupid tube thru the plenum. Have you ever changed the modulator? I have one sitting in the garage if you'd like it.
 
View attachment 1085120
Just bypass the stupid tube thru the plenum. Have you ever changed the modulator? I have one sitting in the garage if you'd like it.

I have not changed it that I can remember. I would love to have it. Is it the little piece attached to the plenum support it the pic? And I didn't even think about bypassing the plenum altogether with it. I didn't know if it needed to go that rout or not.
 
I have not changed it that I can remember. I would love to have it. Is it the little piece attached to the plenum support it the pic? And I didn't even think about bypassing the plenum altogether with it. I didn't know if it needed to go that rout or not.
The modulator is the round component attached to the EGR valve. Takes all of a minute to swap out. Shoot me a PM and we'll talk about getting it out to you.
 
Anyone have a source for good tiny brushes or port cleaners, I have also had the EGR code for years and I have replaced the EGR, VSV, all vacuum lines I could find, cleaned all ports and passages through the Plenum I could find and still the code pops up shortly after clearing... grrrrrrr. I would love to figure this mother out... I am getting really sick of the CEL staring at me all the time...
http://www.grainger.com/category/po...-spiral+brush?nls=1&sst=subset&ts_optout=true
 
Yes. The VSV may not malfunction, but if you don't have vacuum, what is it switching?... Vacuum leaks in the system can cause a code.
Thanks. I will be testing the VSV as per this thread very soon. I'm currently down with a HG replacment, but here is how I rerouted it for a quick change out like ElPolloBlanco.
20150531_202031.jpg
 
We just pulled the hoses and wiring off the VSV and mounted a new one outside of the manifold. Of course it didn't fix my PO401 code, but at least I didn't have to remove the manifold. :meh:


After replacing every part of that crappy EGR system, I'm learning to live with a CEL on my dash.

Unfortunately it will eventually mask a problem with something else. If only someone could find a way to turn off the signal from the EGR fault so others could get through instead.
 
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We just pulled the hoses and wiring off the VSV and mounted a new one outside of the manifold. Of course it didn't fix my PO401 code, but at least I didn't have to remove the manifold. :meh:


After replacing every part of that crappy EGR system, I'm learning to live with a CEL on my dash.

Unfortunately it will eventually mask a problem with something else. If only someone could find a way to turn off the signal from the EGR fault so others could get through instead.

if you've replaced EVERYTHING, have you checked the vacuum passage through the intake? mine's clogged all up, i haven't rerouted yet
 

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