EGR ISSUES
Cargo Master
Joined: Mar 2002
Posts: 3,132
Likes: 219
From: W (BY GOD) V
I finally got some time to troubleshoot my EGR issue. With a hand vacuum pump/ gauge I confirmed the thermal vacuum switch, venturi vacuum amplifier (VVA) and EGR value were all working correctly. I found that the manifold vacuum line going from the carb to the VVA so connected to the incorrect vacuum port on the carb. So the manifold vacuum line on the carb was not providing variable vacuum (based on the throttle position) to the VVA so the VVA was not providing vacuum to the EGR valve. I connected the manifold vacuum line to the correct the vacuum port on the carb. After a test drive the EGR valve is functioning correctly.
GOOD GOING!...
Posting Guru
Joined: Apr 2011
Posts: 1,636
Likes: 5
From: Orlando area
Interesting...
Why the check valve? It would appear that vacuum can be applied to distributor (and EGR when Temp is right), but with a check valve - how does the vacuum release?
It must have a bleed in the EGR/PVS valve (if so, it would need to be "normally open" so vacuum applied to distributor can be dumped and when there is no vacuum available due to throttle opening/position, the dist timing can return to base timing. Then, I assume, when engine temp is correct (hot), it then opens the top port sop vacuum can be applied to both the distributor and EGR. If that is the way it works, then EGR bleed (and distributor) vacuum bleed is through the EGR/PVS valve.
Still not sure why there is a check valve.
Why the check valve? It would appear that vacuum can be applied to distributor (and EGR when Temp is right), but with a check valve - how does the vacuum release?
It must have a bleed in the EGR/PVS valve (if so, it would need to be "normally open" so vacuum applied to distributor can be dumped and when there is no vacuum available due to throttle opening/position, the dist timing can return to base timing. Then, I assume, when engine temp is correct (hot), it then opens the top port sop vacuum can be applied to both the distributor and EGR. If that is the way it works, then EGR bleed (and distributor) vacuum bleed is through the EGR/PVS valve.
Still not sure why there is a check valve.
Cargo Master
Joined: Mar 2002
Posts: 3,132
Likes: 219
From: W (BY GOD) V
That illustration is just a general/simplification of a system. The actual system(s) would most likely be more complex.
The check valve (in this instance) prevents a possible engine backfire from entering the system and causing damage.
Gary Lewis entered these ILL(s) on his website. Did you find them?
The check valve (in this instance) prevents a possible engine backfire from entering the system and causing damage.
Gary Lewis entered these ILL(s) on his website. Did you find them?
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