Testing EGR VSV w/ intake still on? (1 Viewer)

[Pskhaat]

Any way? I've removed the top intake plenum ``hold up'' bar, but wow how could anyone see what is under there without removing it the plenum itself? How does one access the EGR VSV with the plenum still on?

 

[turbocruiser]

Any way? I've removed the top intake plenum ``hold up'' bar, but wow how could anyone see what is under there without removing it the plenum itself? How does one access the EGR VSV with the plenum still on?

FWIW, I tried to contort myself close enough to do the FSM diagnostic with my multimeter and I was not able to reach the terminals on the VSV and read the multimeter at the same time. If I had alligator clips on my leads maybe but alas, I did not, so after verifying that the modulator and the EGR itself were good I took out the VSV, tested it off the vehicle, confirmed it was crap and put the VSV I got from Dan on, problem solved! HTH Ohh, order extra vacuum line and replace anything and everything you can get to including the lines to and from the VSV itself. HTH also!

 

[Pskhaat]

Is the VSV a pressure fit or is it bolted? Do you remember how much for the VSV? And for the modulator for that matter?

 

[turbocruiser]

Is the VSV a pressure fit or is it bolted? Do you remember how much for the VSV? And for the modulator for that matter?

The VSV is bolted by bolts onto the underside of the upper half of the intake plenum. I do not remember how much for either to be honest, and I would not want to misinform, just give Dan the man a PM and see, neither part was enough to even sweat over, the modulator is a piece of cake to put in, no tools no time at all, the VSV was about 1 hour job IIRC and I could probably do it in half the time now. HTH

 

[semlin]

vsv comes out with 2 bolts holding the retaining bar to the plenum without removing the intake plenum. Front one is accessed with an open face wrench from the driver's side under the little gap in the middle of the plenum. Back one is accessed from under neath the truck with a 30" extension bar. It is easier to see than you would think. The vacuum hoses and the harness attached to the vsv are tricky to reattach but it can be done. If you really have trouble, try removing the throttle body. This will give you another side to come at it. You should be cleaning the egr ports on the t-body and the passage in the plenum from egr valve to intake chamber anyway if you have had an egr code so the t-body should come off.

My view is unless you don't mind the truck being off the road while you wait for parts don't bother testing the vsv just have the part ready to replace it if you have an egr code so long as you also replace the modulator if it has any carbon in the filter and all clogged or perished vacuum hoses at the same time. It is not an expensive enough part to be worth the hassle of re and reing twice and the test has been found by some to be inconclusive anyway. One theory is the modulator admits exhaust which leads to carbon in the vacuum system all the way to the vsv which leads to vsv failure so replacing the vsv alone is a symptom cure and is not going to save you longterm.

 

[turbocruiser]

My view is unless you don't mind the truck being off the road while you wait for parts don't bother testing the vsv just have the part ready to replace it if you have an egr code so long as you also replace the modulator if it has any carbon in the filter and all clogged or perished vacuum hoses at the same time. It is not an expensive enough part to be worth the hassle of re and reing twice and the test has been found by some to be inconclusive anyway. One theory is the modulator admits exhaust which leads to carbon in the vacuum system all the way to the vsv which leads to vsv failure so replacing the vsv alone is a symptom cure and is not going to save you longterm.

Agree one hundred percent, good stuff, made me remember something I forgot which was in fact that my VSV when I tested it, tested both bad and good and regardless of how it tested with my multimeter, the airflow through the thing was next to none indicating carbon and crap. I think the order of problems semlin mentioned; mod going bad, VSV getting clogged is exactly what happens, sort of a domino effect. I also agree you should not pull the part, test it, wait for it and put it in; just get the part and put it in regardless - I know this is normally a super stupid strategy for automobile maintenance in general but from my opinion my time was too valuable to do this R&R more than one fricken time and in the end I have more peace of mind about the VSV now as it is new. HTH.

 

[Pskhaat]

Might have to buy a long 3/8" extension bar. Don't have anything nearly that long (extension bar, that is

 

[Beowulf]

Another vote for replacing the VSV once you determine you have a persistent P0401 code. I also agree with Simon's analysis of the EGR modulator problem causing the VSV to fail.

I am beginning to think that a "quick fix" for the P0401 is to replace both VSV and mod at the same time; along with vacuum hoses as needed.

Has anyone permanently fixed a P0401 by replacing the EGR valve, and only the EGR valve? By permanently, I mean 6 months and 6k miles. Several of us have had 3 or 4 month "fixes."

-B-

 

[turbocruiser]

I am beginning to think that a "quick fix" for the P0401 is to replace both VSV and mod at the same time; along with vacuum hoses as needed.

Has anyone permanently fixed a P0401 by replacing the EGR valve, and only the EGR valve? By permanently, I mean 6 months and 6k miles. Several of us have had 3 or 4 month "fixes."

-B-

Another great point! Whew, I was worrying that my "throw some parts at it" answer was wrong but really in this case there is no other point in prolonging all the things that cause problems. Also, AFAIK the EGR is the simplest thing to test in a completely conclusive way...the FSM makes a major ordeal out of testing it and I suppose all those tests are for a further purpose but to start, just put some vacuum on the thing while the engine is idling...it should run like complete crap, if it does, proceed to the throwing of parts cause its gonna be the mod and possibly the VSV!!!

I would also like to know if someone here has fixed a 401 permanently by just cleaning or replacing the EGR valve, on the other hand I KNOW there are people (including myself) who permanently fixed the 401 without ever touching the EGR. Wonder if it works both ways depending on what is actually wrong? Might make for an interesting stand-alone poll that could possibly even goto FAQ section?

 

[Rookie2]

I am beginning to think that a "quick fix" for the P0401 is to replace both VSV and mod at the same time; along with vacuum hoses as needed.

-B-

Basically what I did. I replaced the modulator first because it was green instead of blue. No fixy CEL. Then replace VSV. No more CEL.

The VSV is easy to remove once the TB is off.

My 0.02... learn yourself how to take the TB off. It's not that big of a deal. You should give it a good cleaning anyways. It may take you an hour or so to work through the first time taking it off, but after you've done it once, it's a 15-20 minute deal. You might want to tape one nut down on each of the throttle, kick down and cruise control cables, so you can put them back on in the same location. Just don't overtorque the 4 bolts that fasten it to the intack, and you'll be golden.


Rookie2

 

[Pskhaat]

Rookie2, I've cleaned the TB before whilst off the rig, just trying to bypass taking it apart one more time as it was just off recently (last week) due to HG change. I guess sometimes though you gotta do what you gotta do

 

[semlin]

B-wulf, you raise some good questions. My view is the safest fix is as follows

1. replace EGR valve
2. replace EGR modulator
3. replace all vacuum hoses and ream out the vacuum passage in the plenum
4. replace VSV and carefully check the harness for problems
5. clean throttle body especially clear the EGR ports on top
6. clean passage in intake plenum between EGR valve and intake chamber

If you do all these things at once it will take you 2-4 hours, cost you around $200 in parts and it will cure 99% of all evils. For all the futzing around it takes if you try to fix it piecemeal, this approach makes the most sense to me. If you still get a code then replace the EGR temp sensor which is an easy plug and play fix (a bad egr temp sensor cannot harm the rest of the system), and if that does not work then it must be the vsv harness (which, again, will not have harmed the rest of the system).

The only tough call is whether to automatically replace the EGR valve given it is the most expensive part and seems to be least likely of the three biggies to be the problem. It is relatively easy to replace later but since you have to yank it to clean the plenum passage and since I am not sure whether it can damage the new modulator (and start the failure of the VSV) if it is faulty, I would replace it right away myself. If you have a clean modulator filter and no apparent vacuum line blockages I would suspect the EGR valve for sure.

 

[pound3151]

I've been using the "clear codes" button on my scanner every few months (quick fix). Can this actually hurt anything in the long run or am I fine to wait for summer to do the work?

 

[Beowulf]

I've been using the "clear codes" button on my scanner every few months (quick fix). Can this actually hurt anything in the long run or am I fine to wait for summer to do the work?

Technically, a failing EGR system can cause detonation problems. I cannot recall anyone reporting this as a problem when their P0401 code appeared. General repair books also say it can cause the vehicle to run hotter and may cause it to run rough. Again, nobody that I know of has reported these problems on the 1FZ-FE engine.

The big deal for me was the nusiance of the darn MIL light staring at you all the time and the worry that the MIL could be masking other, more serious, problems. You wouldn't want to run the vehicle until summer if it has a lean condition. The noise from the passenger seat also gets annoying.

-B-

 

[landtoy80]

For what its worth:
You should remove the intake chamber if its the first time removing the VSV.
The bar bolts can be removed with long extensions.
The screws that hold the VSV on the bar may need a needle nose vicegrips to remove them.
You will strip them if they they need the vicegrips to remove them.
Once you have remove it and used anti-sieze in the screws and bolts, you can easily remove them a second time.

I tested the VSV once and it was fine. Replace the modulator and CE light came back on after some time. Tested the VSV again and it failed. Replaced it and it hasen't (note, i didn't say NEVER) come back.

 

[cruiserdan]

The noise from the passenger seat also gets annoying.

-B-

Um, Put a fridge there like Bill did...................





Problem solved..........

 

[Rookie2]

I tested the VSV once and it was fine. Replace the modulator and CE light came back on after some time. Tested the VSV again and it failed. Replaced it and it hasen't (note, i didn't say NEVER) come back.

I too tested the VSV, and it seemed to test out okay. However, with an intermitant CEL, I figured the VSV may be working fine at times and then tripping the code at others. Replacing the VSV appears to have elliminated my CEL. Point being, it may be to conclude the VSV is falty by testing, if the CEL is intermitant as mine was. JMO.


Rookie2

 

[landtoy80]

Inside the VSV is a tiny: diaphram,spring and electro magnet.
Carbon can get in the VSV could block the vacuum port or lodge in the diaphram and make it stay open.
Over time the tiny spring that pushes on the diaphram will get weak. This could cause the VSV to fail.