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#1
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No Ported Vacuum
Hi All,
I am not getting any ported vacuum going to my EGR valve. I checked the vac at the connection that is on the top of the Carter BBD - the one on the engine side of the carb and there is no vacuum at any RPM. Anyone have any ideas why? Thanks in advance, Steve |
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#2
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No Ported Vacuum
Because the vacuum at that port depends on load? Have you triple-checked to
make sure that it is the correct port? Earle "steve" > wrote in message ... > Hi All, > > I am not getting any ported vacuum going to my EGR valve. I checked the vac > at the connection that is on the top of the Carter BBD - the one on the > engine side of the carb and there is no vacuum at any RPM. Anyone have any > ideas why? > > Thanks in advance, > Steve > > > |
#3
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No Ported Vacuum
Then I would guess someone put the carb's base gaskets on wrong. There
are channels in them that direct the vacuum flow. Do you have manifold vacuum at any ports? Mike 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's Canadian Off Road Trips Photos: Non members can still view! Aug./05 http://www.imagestation.com/album/in...?id=2120343242 (More Off Road album links at bottom of the view page) steve wrote: > > Hi All, > > I am not getting any ported vacuum going to my EGR valve. I checked the vac > at the connection that is on the top of the Carter BBD - the one on the > engine side of the carb and there is no vacuum at any RPM. Anyone have any > ideas why? > > Thanks in advance, > Steve |
#4
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No Ported Vacuum
One other thing, the hole could just be plugged. Maybe try spraying
some carb cleaner into the nipple to see if it comes out on the inside. Mike Mike Romain wrote: > > Then I would guess someone put the carb's base gaskets on wrong. There > are channels in them that direct the vacuum flow. > > Do you have manifold vacuum at any ports? > > Mike > 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 > 88 Cherokee 235 BFG AT's > Canadian Off Road Trips Photos: Non members can still view! > Aug./05 http://www.imagestation.com/album/in...?id=2120343242 > (More Off Road album links at bottom of the view page) > > steve wrote: > > > > Hi All, > > > > I am not getting any ported vacuum going to my EGR valve. I checked the vac > > at the connection that is on the top of the Carter BBD - the one on the > > engine side of the carb and there is no vacuum at any RPM. Anyone have any > > ideas why? > > > > Thanks in advance, > > Steve |
#5
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No Ported Vacuum
Thanks for all the advice...but, I have checked if the port is clear
(sprayed cleaner through it), the carb gasget has never been removed or replaced, and I do have vacuum at the manifold ports. When you say the ported vacuum depends on load, should I still get some vacuum if I just rev the engine? "steve" > wrote in message ... > Hi All, > > I am not getting any ported vacuum going to my EGR valve. I checked the > vac at the connection that is on the top of the Carter BBD - the one on > the engine side of the carb and there is no vacuum at any RPM. Anyone > have any ideas why? > > Thanks in advance, > Steve > |
#6
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No Ported Vacuum
If I remember my emissions control theory right, the EGR is supposed to work
at part throttle, not full load, when the mixture, caused by the other emissions controls, is too lean. You inject exhaust gas into the too-lean mixture, and it makes it less lean, without making it richer. This lowers the combustion temperature, and theoretically oxides of nitrogen. If you think about it, this means that your EGR isn't designed to kick in when you are idling, or playing with the throttle in your garage. You have to be going down the road, with a certain amount of air flowing, burning a certain amount of fuel, to get appreciable vacuum at that port. This means also that your state emissions compliance program isn't going to succeed in testing the operation of your EGR valve, unless they have a chassis dynamometer, and maybe not even then. I had a car in Washington State pass with flying colors, even though they put the car on the dynamometer and ran it at 30 mph, with the under-vehicle part of the EGR plumbing, completely rotted through and brazed shut. Why do you want the EGR working? It isn't going to do anything, except plug the filter, rot the plumbing, and eventually stop working by itself. The theory is somewhat plausible, but the effect on emissions is negligible at best. I don't really know why you are not getting vacuum at that port, but I suspect that you may not, with the vehicle in the garage. Are you absolutely sure it is the correct port for the EGR? Earle "steve" > wrote in message ... > Thanks for all the advice...but, I have checked if the port is clear > (sprayed cleaner through it), the carb gasget has never been removed or > replaced, and I do have vacuum at the manifold ports. When you say the > ported vacuum depends on load, should I still get some vacuum if I just rev > the engine? > > "steve" > wrote in message > ... > > Hi All, > > > > I am not getting any ported vacuum going to my EGR valve. I checked the > > vac at the connection that is on the top of the Carter BBD - the one on > > the engine side of the carb and there is no vacuum at any RPM. Anyone > > have any ideas why? > > > > Thanks in advance, > > Steve > > > > > |
#7
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No Ported Vacuum
I have the top valve cover side nipple on my BBD hooked via a T-fitting
to my distributor and CTO valve. The CTO valve then powers the air filter switch for the EGR valve. The EGR valve has a vacuum delay disk in the line. If this disk is backward, the EGR will not see vacuum. When I am sitting at an idle and I give the engine a shot of gas, I can see and hear my distributor advance physically move in perfect time to the gas pedal. When I punch it, I have full advance. I don't understand how there can be no ported vacuum if the nipple sprays clear with cleaner. Mike 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's Canadian Off Road Trips Photos: Non members can still view! Aug./05 http://www.imagestation.com/album/in...?id=2120343242 (More Off Road album links at bottom of the view page) steve wrote: > > Thanks for all the advice...but, I have checked if the port is clear > (sprayed cleaner through it), the carb gasget has never been removed or > replaced, and I do have vacuum at the manifold ports. When you say the > ported vacuum depends on load, should I still get some vacuum if I just rev > the engine? > > "steve" > wrote in message > ... > > Hi All, > > > > I am not getting any ported vacuum going to my EGR valve. I checked the > > vac at the connection that is on the top of the Carter BBD - the one on > > the engine side of the carb and there is no vacuum at any RPM. Anyone > > have any ideas why? > > > > Thanks in advance, > > Steve > > |
#8
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No Ported Vacuum
Hi Steve,
I don't know how the AMC six is set up, other than the diagram at: http://home.sprynet.com/~dale02/vac-egr.htm On my Ford there are many valves the vacuum goes through on the way toe Exhaust Gases Recycling valve. Remember you don't want it wide open pouring exhaust into the intake manifold at idle. So on a Ford one of the control valves is operate by the venturi vacuum port that only has vacuum with the high velocity of air passing through the venturi, which looks like this on a Ford: http://www.billhughes.com/decelValve.jpg God Bless America, Bill O|||||||O steve wrote: > > Thanks for all the advice...but, I have checked if the port is clear > (sprayed cleaner through it), the carb gasget has never been removed or > replaced, and I do have vacuum at the manifold ports. When you say the > ported vacuum depends on load, should I still get some vacuum if I just rev > the engine? > > "steve" > wrote in message > ... > > Hi All, > > > > I am not getting any ported vacuum going to my EGR valve. I checked the > > vac at the connection that is on the top of the Carter BBD - the one on > > the engine side of the carb and there is no vacuum at any RPM. Anyone > > have any ideas why? > > > > Thanks in advance, > > Steve > > |
#9
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No Ported Vacuum
steve alleged...
> Thanks for all the advice...but, I have checked if the port is clear > (sprayed cleaner through it), the carb gasget has never been removed or > replaced, and I do have vacuum at the manifold ports. When you say the > ported vacuum depends on load, should I still get some vacuum if I just rev > the engine? > > "steve" > wrote in message > ... > > Hi All, > > > > I am not getting any ported vacuum going to my EGR valve. I checked the > > vac at the connection that is on the top of the Carter BBD - the one on > > the engine side of the carb and there is no vacuum at any RPM. Anyone > > have any ideas why? > > > > Thanks in advance, > > Steve > > > > > If you briefly crack the throttle maybe a quarter open, you should definitely see vacuum at the port. You should be able to feel it with your finger, and it's enough to pull the EGR open slightly. Assuming you find that you do indeed have ported vacuum, the EGR should still not work if the engine is not warmed up. Check this diagram: http://home.sprynet.com/~dale02/vac-egr.htm Check for vacuum at the carb port, in/out of the CTO, and in/out of the TVS in the air cleaner. Check the canister purge line for a massive leak. -- Dale Beckett |
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