- Thread starter
- #21
Thanks, i just bypassed it all. After it passed the smog test, i put a BB in line before the EGR so the EGR will remain closed at all times.
'94 FJ80 - Why no Vacuum to EGR?? (1 Viewer)
- Thread starter LandCrawler
- Start date
This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.
.
Last edited:
I just deleted my PAIR and EGR systems and if my memory serves me correct the TVV vacuum lines route to the EVAP system. I do not believe the TVV plays any part in the EGR system.
Just figured that out. Thanks! I'm focusing on vacuum supply, now that the egr parts are new.
Where does the vacuum start ... routing wise? and which was does it flow? from manifold i know, but which port or hose does it start at? i get lost under the throttle body...
Elaborating ...
where does this line go to?
where does this line go to?
ppc
M Go Blue
Looks to be the metal hard line that is routed underneath the top intake manifold to supply vacuum to one or more of the vacuum switching valves.
Dug in. Further. It's on the bottom front of the intake, just after the throttle body. Looks to supply several of the VSVs.. I'll take a pic for knowledge capturing purposes.
Such an informative thread!
I'm right at a similar point as in the above quote... no vacuum to the egr. Gauge hooked up between the modulator and valve, no vacuum... I can blow through all the hoses and passages/metal lines, and through the ports into the throttle body... I assume then that they are all clear of blockage. So how could it be that I still have no vacuum?
The only thing I havent tried is hooking the source vacuum [the port on the front bottom of the I take, right after the throttle body] straight to the vsv. This would I believe, disable the other systems reliant on the port.... But would allow me use that result to narrow down where the issue is.
Say there is a bad 1 way vacuum valve or a hose off some where, perhaps a different vsv that's not working , essentially creating a vacuum leak? The source port seems to feed all the vsvs under the clam shell... no?
I'm getting about to the limit of my problem solving abilities, and patience.... not to mention 4 wheeling season is ALMOST here!!!
Thanks
Last edited:
Something else I just read, blowing into the right port of the egr, with the other side blocked, engages the egr. This leads me to believe the vacuum source is 1 or both the ports on the throttle body, E and R that goto the modulator.
Thoughts?
Thoughts?
ToyotaDon
I am here
That test you are talking about is for the modulator and basically is a way to test it with air instead of vacuum.
If you have a vacuum gauge, connect it to each hose in turn, starting at the EGR valve and working your way back to the throttle body. It won't register very high, due to the type of vacuum sources that are used, but should show something on the gauge when you accelerate. If nothing on any hose, then you have a blockage or leak. If you have vacuum to both modulator hoses, then check the bottom hose for exhaust, which is what "turns on" the modulator. Having all those signals without vacuum from the third hose would condemn the modulator.
Now, the final factor is the VSV, which acts as a vent for the vacuum provided to the EGR valve. It has to be turned on by the ECM and should be once the engine is warmed up. Since it doesn't provide vacuum, we can't check it with a vacuum gauge, but usually use a vacuum pump to test it. This system is one case where just following the steps in the book can be confusing. We have to come up with our own tests based on knowledge of the system.
If you have a vacuum gauge, connect it to each hose in turn, starting at the EGR valve and working your way back to the throttle body. It won't register very high, due to the type of vacuum sources that are used, but should show something on the gauge when you accelerate. If nothing on any hose, then you have a blockage or leak. If you have vacuum to both modulator hoses, then check the bottom hose for exhaust, which is what "turns on" the modulator. Having all those signals without vacuum from the third hose would condemn the modulator.
Now, the final factor is the VSV, which acts as a vent for the vacuum provided to the EGR valve. It has to be turned on by the ECM and should be once the engine is warmed up. Since it doesn't provide vacuum, we can't check it with a vacuum gauge, but usually use a vacuum pump to test it. This system is one case where just following the steps in the book can be confusing. We have to come up with our own tests based on knowledge of the system.
k, so i have 4hg vacuum on btwn the modulator and egr valve, after plugging the hose that comes out the drivers side of the egr that goes to the vsv. i am thinking 4 hg is "low" vacuum.... i don't get a higher vacuum reading when connecting port r direct to manifold (which by the way, is a little vague... where is that exactly?)
considering putting a bb in that plugged hose to try emissions again... ??
considering putting a bb in that plugged hose to try emissions again... ??
ToyotaDon
I am here
That should be enough to activate the valve. You probably have a bad VSV, so check out the threads on replacing and relocating that.
Already had a new one relocated prior to the issue, and it tests fine. suspecting a bad check valve perhaps?
ToyotaDon
I am here
What check valve would you be talking about?
Both of the 2 black/ orange vacuum check valves.... wouldn't a bad one sorta make a "vacuum leak" ?
PASSED EMISSIONS!
I was running 5.5 - 7.2 NOX in the past 4 tests. The ONLY thing that changed the readings down to 1.4!!! on the passing test was the egr. operating in some fashion.
I ended up blocking the line coming out of the drivers side of the egr valve ( put a plug down in the hose and re-attached) . The vacuum gauge hooked up between the modulator and the valve, i get no vacuum at idle, increasing vacuum up to 4hg at about 25% throttle, then it deceases to 0hg as more throttle is applied... I never get a high vacuum state, nor any vacuum on decel like I think the manual says.... but it was enough to lower NOX to well with in range to pass...
I was running 5.5 - 7.2 NOX in the past 4 tests. The ONLY thing that changed the readings down to 1.4!!! on the passing test was the egr. operating in some fashion.
I ended up blocking the line coming out of the drivers side of the egr valve ( put a plug down in the hose and re-attached) . The vacuum gauge hooked up between the modulator and the valve, i get no vacuum at idle, increasing vacuum up to 4hg at about 25% throttle, then it deceases to 0hg as more throttle is applied... I never get a high vacuum state, nor any vacuum on decel like I think the manual says.... but it was enough to lower NOX to well with in range to pass...
I had to remove my tbody to clean the ports. They were plugged bad and had to use a sewing needle to clear them out. I also had no vacuum to vsv. That and a new modulator fixed my egr issue.
nice! I am able to blow through them ... I am assuming that means they are not plugged. Unless they share some port space inside or something ...
Ok. Sounds like they are clear. Do you have the P0401 code?
