What I think your reading is the resistance of the coil of the switch. Personally I usually supply 12v and check flow through the valve. Others have had bad readings similar to yours which always didn't help the situation when replaced.
Testing VSV for EGR
- Thread starter landtank
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R2,
I don't think that small of a difference would cause a hard failure. Mine tested something like 40,000 ohms when it failed.
-B-
I don't think that small of a difference would cause a hard failure. Mine tested something like 40,000 ohms when it failed.
-B-
The problem with the VSV is that if it gets a bit of carbon in the valve it will not open close. It will test fine but when you put it back it can/will/maybe fail. It seems to work one time, then fail others.
What was the temp. out when you tested it?
You have check your EGR modulator?
So just replace it. Just ask Junk, if you replace enough parts it will be fixed..... maybe
What was the temp. out when you tested it?
You have check your EGR modulator?
So just replace it. Just ask Junk, if you replace enough parts it will be fixed..... maybe
[quote author=landtoy80 link=board=2;threadid=17212;start=msg166831#msg166831 date=1086011140]
The problem with the VSV is that if it gets a bit of carbon in the valve it will not open close. It will test fine but when you put it back it can/will/maybe fail. It seems to work one time, then fail others.
[/quote]
With this in mind, I'm wondering would any sort of injection system cleaner such as the BG 44K help remove any amount of carbon in the EGR system? Would the cleaner even effectively make its way into the VSV? I recently pulled the PO401 and after following the FSM realized that the vacuum modulator was faulty. So if any extra carbon or crap got into the VSV, then it could test okay but still stick possibly!?! If I thought that the 44K, or anything applied directly, would safely clean carbon out, I'd run another can through the tank. The last time I ran a can through was 5000miles ago but that was way before the PO401. Any thoughts? Thanks.
The problem with the VSV is that if it gets a bit of carbon in the valve it will not open close. It will test fine but when you put it back it can/will/maybe fail. It seems to work one time, then fail others.
[/quote]
With this in mind, I'm wondering would any sort of injection system cleaner such as the BG 44K help remove any amount of carbon in the EGR system? Would the cleaner even effectively make its way into the VSV? I recently pulled the PO401 and after following the FSM realized that the vacuum modulator was faulty. So if any extra carbon or crap got into the VSV, then it could test okay but still stick possibly!?! If I thought that the 44K, or anything applied directly, would safely clean carbon out, I'd run another can through the tank. The last time I ran a can through was 5000miles ago but that was way before the PO401. Any thoughts? Thanks.
The vacuum system gets it vacuum from the throttle body so the cleaner would never reach the vacuum system.
The reason carbon gets into the vacuum system if from a bad modulator. When the modulator gets a crack in the diaphram, it lets carbon in the vacuum system.
I wouldn't put anything in the vacuum system. It could screw up other parts of the vacuum system, I think.
The reason carbon gets into the vacuum system if from a bad modulator. When the modulator gets a crack in the diaphram, it lets carbon in the vacuum system.
I wouldn't put anything in the vacuum system. It could screw up other parts of the vacuum system, I think.
[quote author=landtoy80 link=board=2;threadid=17212;start=msg166842#msg166842 date=1086013851]
The vacuum system gets it vacuum from the throttle body so the cleaner would never reach the vacuum system.
The reason carbon gets into the vacuum system if from a bad modulator. When the modulator gets a crack in the diaphram, it lets carbon in the vacuum system.
I wouldn't put anything in the vacuum system. It could screw up other parts of the vacuum system, I think.
[/quote]
Okay, good to know, thanks. So I think that the next question is, when the vacuum modulator's diaphram goes bad, does it immediately foul up the vsv? IOW, since I know that the diaphram was bad, do I assume that the VSV is fouled up even if it tests okay? As soon as the PO401 alert came on, I drove home and did not drive again til the replacement came up from CruiserDan which was almost instantaneous, thanks Dan. So, not sure how long the diaphram was bad before the code came up but I drove less than five miles with the code up. The filter in the modulator was only slightly carbon-ed and there was no visible carbon crud in the modulator or in any of the three hoses. There was a carbon soot sort of film on the hoses but it was not any added up amount anywhere like that pic of that modulator that was posted. Thanks again for answering about the EGR system...makes perfect sense that a fuel injection system cleaner cannot help here. Would those cleaners that are advertised as air intake cleaners be safe to squirt through the throttle body and would that possibly help in some small way with the carbon in the EGR system? Thanks again.
The vacuum system gets it vacuum from the throttle body so the cleaner would never reach the vacuum system.
The reason carbon gets into the vacuum system if from a bad modulator. When the modulator gets a crack in the diaphram, it lets carbon in the vacuum system.
I wouldn't put anything in the vacuum system. It could screw up other parts of the vacuum system, I think.
[/quote]
Okay, good to know, thanks. So I think that the next question is, when the vacuum modulator's diaphram goes bad, does it immediately foul up the vsv? IOW, since I know that the diaphram was bad, do I assume that the VSV is fouled up even if it tests okay? As soon as the PO401 alert came on, I drove home and did not drive again til the replacement came up from CruiserDan which was almost instantaneous, thanks Dan. So, not sure how long the diaphram was bad before the code came up but I drove less than five miles with the code up. The filter in the modulator was only slightly carbon-ed and there was no visible carbon crud in the modulator or in any of the three hoses. There was a carbon soot sort of film on the hoses but it was not any added up amount anywhere like that pic of that modulator that was posted. Thanks again for answering about the EGR system...makes perfect sense that a fuel injection system cleaner cannot help here. Would those cleaners that are advertised as air intake cleaners be safe to squirt through the throttle body and would that possibly help in some small way with the carbon in the EGR system? Thanks again.
[quote author=turbocruiser link=board=2;threadid=17212;start=msg166852#msg166852 date=1086015719]
As soon as the PO401 alert came on, I drove home and did not drive again til the replacement came up from CruiserDan which was almost instantaneous, thanks Dan.
[/quote]
T-cruiser,
So what's the big fuss? I've been driving with an intermitent P0401 for a couple of weeks. My understanding is that when there's a malfunction in the EGR system, it stops working. So you don't get the exhaust recirculation, which some consider a good thing, until testing time comes along that is.
Thanks,
Rookie2
As soon as the PO401 alert came on, I drove home and did not drive again til the replacement came up from CruiserDan which was almost instantaneous, thanks Dan.
[/quote]
T-cruiser,
So what's the big fuss? I've been driving with an intermitent P0401 for a couple of weeks. My understanding is that when there's a malfunction in the EGR system, it stops working. So you don't get the exhaust recirculation, which some consider a good thing, until testing time comes along that is.
Thanks,
Rookie2
[quote author=Rookie2 link=board=2;threadid=17212;start=msg166875#msg166875 date=1086022632]
T-cruiser,
So what's the big fuss? I've been driving with an intermitent P0401 for a couple of weeks. My understanding is that when there's a malfunction in the EGR system, it stops working. So you don't get the exhaust recirculation, which some consider a good thing, until testing time comes along that is.
[/quote]
Well, ahhgehhm, I am a self-diagnosed hypochondriac with whatever we own and preventive maintenance and proactive repairs are what I am all about baaaabbbby!
Yes, I realize there are terrific medications to treat these things, but my method much more fun!!! 
Besides, not supposed to mix alcohol with meds, so I'm gonna stay pure, or pure alcohol actually, as long as possible!!!
Seriously though, one reason I always approach all these things with an overkill squared approach is the turbo system. I think that it requires more attention to the total tuning of the vehicle. Also, I have heard that the EGR system, when operating properly can lower combustion temperatures somewhat or significantly depending on who one asks. So if that is the truth then between a faulty EGR system and a turbo system, might not make a good mix. Might not make much difference either but the hypochondriac in me throws that possibility out!!! Lastly, supposing that the modulator slowly fouls up the vsv, then by driving with a bad modulator, you are also getting a bad vsv. Who knows, something to worry about though I say!!!
T-cruiser,
So what's the big fuss? I've been driving with an intermitent P0401 for a couple of weeks. My understanding is that when there's a malfunction in the EGR system, it stops working. So you don't get the exhaust recirculation, which some consider a good thing, until testing time comes along that is.
[/quote]
Well, ahhgehhm, I am a self-diagnosed hypochondriac with whatever we own and preventive maintenance and proactive repairs are what I am all about baaaabbbby!
Yes, I realize there are terrific medications to treat these things, but my method much more fun!!! Besides, not supposed to mix alcohol with meds, so I'm gonna stay pure, or pure alcohol actually, as long as possible!!! Seriously though, one reason I always approach all these things with an overkill squared approach is the turbo system. I think that it requires more attention to the total tuning of the vehicle. Also, I have heard that the EGR system, when operating properly can lower combustion temperatures somewhat or significantly depending on who one asks. So if that is the truth then between a faulty EGR system and a turbo system, might not make a good mix. Might not make much difference either but the hypochondriac in me throws that possibility out!!! Lastly, supposing that the modulator slowly fouls up the vsv, then by driving with a bad modulator, you are also getting a bad vsv. Who knows, something to worry about though I say!!!
semlin
curmudgeon
I would not assume your diagnostic computer automatically finds an egr problem as soon as it happens. I had a completely blocked egr system on my 93 and I never got any codes at all (although my model has no temp sensor).
There are at least 3 possible reasons for EGR failure
1. modulator valve fails and lets carbon into vacuum lines and stuff gets blocked or shorted out
2. egr flow is blocked from carbon buildup in passage from egr valve to intake chamber
3. something else just breaks (vsv for EGR valve, egr valve, etc..)
It is also possible that a blocked egr flow leads to 1, since people with bad modulators often seem to find carbon buildup when they pull their egr valve.
Whatever it is, I would not assume replacing the VSV will fix it. Exhaust flow through the vacuum hoses does seem to wreck the vsv but it can wreck or block other stuff too. I'm not sure if it is carbon shorting the vsv or the exhaust gas itself. On my system the exhaust gas had coated some unblocked hoses with a kind of oily residue and had rusted the metal nipples on the egr valve and at other points. Modulator failure means carbon and exhaust gas has been circulating inside your vacuum system even if it hasn't led to a blockage yet. There could be a blockage elsewhere in the system.
Apart from replacing the vsv I would at minimum check every vacuum hose in the system for blockage, and especially check there is free flow through the egr ports on top of the throttle body into the throttle body chamber (very tiny holes), and also the junction where the hose from the egr valve passes through the air intake chamber..
If that does not fix your troubles, I would pull the egr valve next and the check for carbon blockage, and I would think about replacing the egr valve (or at least testing it according to the factory test).
There are at least 3 possible reasons for EGR failure
1. modulator valve fails and lets carbon into vacuum lines and stuff gets blocked or shorted out
2. egr flow is blocked from carbon buildup in passage from egr valve to intake chamber
3. something else just breaks (vsv for EGR valve, egr valve, etc..)
It is also possible that a blocked egr flow leads to 1, since people with bad modulators often seem to find carbon buildup when they pull their egr valve.
Whatever it is, I would not assume replacing the VSV will fix it. Exhaust flow through the vacuum hoses does seem to wreck the vsv but it can wreck or block other stuff too. I'm not sure if it is carbon shorting the vsv or the exhaust gas itself. On my system the exhaust gas had coated some unblocked hoses with a kind of oily residue and had rusted the metal nipples on the egr valve and at other points. Modulator failure means carbon and exhaust gas has been circulating inside your vacuum system even if it hasn't led to a blockage yet. There could be a blockage elsewhere in the system.
Apart from replacing the vsv I would at minimum check every vacuum hose in the system for blockage, and especially check there is free flow through the egr ports on top of the throttle body into the throttle body chamber (very tiny holes), and also the junction where the hose from the egr valve passes through the air intake chamber..
If that does not fix your troubles, I would pull the egr valve next and the check for carbon blockage, and I would think about replacing the egr valve (or at least testing it according to the factory test).
ppc
M Go Blue
Except that EGR under the certain conditions cools the intake charge which can be very important for a forced induction motor. Still nothing to ignore for any engine. T-C, if the MIL turned on it is not a critical thing in that you only drove another 5 miles but that it takes time for an EGR type of error to manifest itself. Any and all components must be properly diagnosed.
