EGR Amplifier

[Ragnar]

I’ve been looking at the EGR system on my 318. The temperature control valve is not connected at all and the amplifier has one of it’s lines already plugged. Can I just ditch the amplifier? The control valve and manifold vacuum inlet are still there. Do I just plug everything up? I’ve no idea if the system even works without the temperature control valve connected, but it’s been like this since I had the car.

 

[RJRENTON]

I’ve been looking at the EGR system on my 318. The temperature control valve is not connected at all and the amplifier has one of it’s lines already plugged. Can I just ditch the amplifier? The control valve and manifold vacuum inlet are still there. Do I just plug everything up? I’ve no idea if the system even works without the temperature control valve connected, but it’s been like this since I had the car.

IMO...
I believe the EGR system was added in the middle 70's for NOx emission conttol. The temp conttol valve was added to inhibit EGR operation below 140° F (temperature varies year to year). Not exactly what you mean with regard to the "amplifier". Some EGR systems used a vacuum amplifier to modulate the vacuum apply dignal to the EGR valve. It did this by balancing the EGR open signal with the EGR's back pressure signal value to close the valve to provide more "effective" EGR operation. GM had a back pressure regulated EGR valve for less plumbing...but the vehicle still ran poorly.
Since EGR (exhaust gas) is added to the fuel charge in the intake manifold, in an effort to reduce combustion chamber temps to below 1600° F, thereby LIMITING NOx formation. EGR usually cripples engine performance for a decrease in emissions. If it were me, depending if you want to maintain an original looking car, connect everything....except put a small plug (like a small ball bearing or split shot fishing sinker) in the EGR valve's vacuum line. Everything looks like it should but doesn't work. If it doesn't matter you can remove evetything, make a blank off plate in place of the EGR valve. Just my opinion of course.
BOB RENTON

 

[383man]

The vacuum amplifier actually had venturi vacuum going to it as it used that signal to determine when to put the manifold vacuum that also goes to the amplifier to the EGR valve. The amplifiers I remember did not use exh back pressure as that was either a separate transducer valve that had exh back pressure to it or it was built into the EGR valve as some used the EXH back pressure going up the stem of the EGR valve to close the vacuum valve for the EGR to work. The vacuum amplifier basically sent manifold vacuum to open the EGR valve by using the signal from venture vacuum. So it has manifold vacuum and venturi vacuum to the amplifier and as said it was controlled by a temp switch that kept the EGR from working until the eng warmed up some. I know on some year engines if the EGR was unhooked and not working some engines would ping/detonate right away since most of them years had no quench with the low comp they ran and the EGR lowered the combustion chamber temps it by putting inert dead exh gas into the cyl that cant reburn and helped fight eng detonation. As said some used exh back pressure to them also as many used a transducer that had the Exh piped to it and it used exh back pressure to close the valve and send the vacuum to the EGR valve. They usually had to build up so much exh back pressure before the transducer valve closed and stopped bleeding the vacuum off and then sent vacuum to open the EGR valve. I worked at Ford in the 70's and I can tell you most of them would ping as soon as the EGR stopped working. But not all Mopars do. As RJRENTON said many times we would use vacuum delay valves or a BB in the vacuum line to delay the EGR as on many Emission engines it could cause a surge since they ran so lean so we would bring the EGR valve in later. We even tapped the valve with a hammer on some to make the valve thinner and that made the spring stiffer so it opened later. If its not working now and the eng is not pinging then you can leave it unhooked as long as your state don't test your cars for NOX emissions. Good luck , Ron

 

[RJRENTON]

The vacuum amplifier actually had venturi vacuum going to it as it used that signal to determine when to put the manifold vacuum that also goes to the amplifier to the EGR valve. The amplifiers I remember did not use exh back pressure as that was either a separate transducer valve that had exh back pressure to it or it was built into the EGR valve as some used the EXH back pressure going up the stem of the EGR valve to close the vacuum valve for the EGR to work. The vacuum amplifier basically sent manifold vacuum to open the EGR valve by using the signal from venture vacuum. So it has manifold vacuum and venturi vacuum to the amplifier and as said it was controlled by a temp switch that kept the EGR from working until the eng warmed up some. I know on some year engines if the EGR was unhooked and not working some engines would ping/detonate right away since most of them years had no quench with the low comp they ran and the EGR lowered the combustion chamber temps it by putting inert dead exh gas into the cyl that cant reburn and helped fight eng detonation. As said some used exh back pressure to them also as many used a transducer that had the Exh piped to it and it used exh back pressure to close the valve and send the vacuum to the EGR valve. They usually had to build up so much exh back pressure before the transducer valve closed and stopped bleeding the vacuum off and then sent vacuum to open the EGR valve. I worked at Ford in the 70's and I can tell you most of them would ping as soon as the EGR stopped working. But not all Mopars do. As RJRENTON said many times we would use vacuum delay valves or a BB in the vacuum line to delay the EGR as on many Emission engines it could cause a surge since they ran so lean so we would bring the EGR valve in later. We even tapped the valve with a hammer on some to make the valve thinner and that made the spring stiffer so it opened later. If its not working now and the eng is not pinging then you can leave it unhooked as long as your state don't test your cars for NOX emissions. Good luck , Ron

EXCELLENT explanation of the EGR vacuum amplifier's function and operation. The EGR valves I noted were a GM design, were either positive back pressure or sometimes negative back pressure regulated to modulate the valve's operation, in aaddition to the valve's ported vacuum opening signal.
You are correct, Ford engines seemed to be more sensitive to EGR, or lack thereof, as you mentioned, due to combustion chamber configuration. A colleague had a 1982 Ford 250 6 cyl in his daily driver, which would ping and detonate ptofusely, if EGR was not present, due to a system malfunction.

I agree with your supposition regarding EGR's operation: "If its not working now and the eng is not pinging then you can leave it unhooked as long as your state don't test your cars for NOX emissions".
When I lived in Pa., we were required to emission inspections annually. All collected data was sent to the State department of Transportation in real time, with a computer, by the car's VIN....MY guy had a test "mule" that took the test with my car's VIN....and everyone lived happily ever after.
BOB RENTON