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EGR delete

stevolwevol

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May 28, 2015
Messages
239
Location
Michigan
Corvette
1977 light blue
I want to delete the EGR from my 79. There is a vacuum hose that leads from the EGR to the front of the intake, then it goes to the carb, but it splits off before the carb, and goes where? Any help or suggestions would be appreciated.
 

Tom Bryant

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7,195
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Edgerton, Ohio, United States
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1959 black 270hp (9/2/69) 1981 Beige L81(10/20/80)
Here's a diagram I found on the Google box. Back when we had annual inspections I'd unplug the EGR hose and push a small ball bearing up the hose to block it off. Then plug the hose back in. Nobody knew. If the EGR is sticking you can force it close with a screwdriver then plug the hose so it can't open again.
 

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stevolwevol

Well-known member
Joined
May 28, 2015
Messages
239
Location
Michigan
Corvette
1977 light blue
Well, that diagram confirms what my thoughts were. the hose that splits off goes to the vacuum canister. I want to get rid of this to reduce the clutter of vacuum hoses, and the EGR as well. My guess is that it's not functioning anyway, and if it were the function seems gratuitous as far a being an effective smog reduction devise. (no testing were I live either). In your opinion, would be a good thing to plug the hose right at the canister? The only difference is the hose that splits to the canister is the hose coming from the part in the intake, not going to it. Maybe this diagram is generic, and varies from year, to engine, etc. I have a box of various plugs for things like this. by plugging the EGR with a delete plate, and plugging the carb, and the canister I should not have vacuum issues, what say you Tom?
 
Joined
Oct 20, 2008
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923
Location
Portage, Indiana
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2010 Grand Sport Vert JS Blue
How do you figure that your gas tank will vent?? Getting an older cap?? Getting rid of the EGR can be a mistake too...
 

stevolwevol

Well-known member
Joined
May 28, 2015
Messages
239
Location
Michigan
Corvette
1977 light blue
How do you figure that your gas tank will vent?? Getting an older cap?? Getting rid of the EGR can be a mistake too...

Are you saying if I plug my hose leading from the EGR to the canister will result in a vent issue with the gas tank?
 

Tom Bryant

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1959 black 270hp (9/2/69) 1981 Beige L81(10/20/80)
This diagram says it's a '79 Corvette but who knows? The gas tank vents to the vapor canister. Vapors are stored in the canister until the engine is run then are drawn into the carb and burned. The engine vacuum opens the upper purge valve (in the diagram) on the canister allowing the vapors to be drawn through the pcv hose back into the carb to burn. The fitting on the intake that the EGR hose runs into is a thermal switch. At a specified temperature the switch opens allowing vacuum to the EGR and the vapor canister upper purge valve. So this is a part time vacuum depending on engine temperature. That second vacuum line coming from the other vapor canister purge valve goes straight to the carb so it is probably full time vacuum and appears to close the lower (in the diagram) purge valve when the engine is running. Anyway, you need the vacuum to the purge valves to allow the fuel tank to be vented.

In my opinion I would not disconnect the vacuum lines to the canister. You could remove the T in the line and eliminate the EGR but leave the thermal switch control of the vapor canister. I always looked at the EGR as a device that pollutes the intake charge. Every pre computer controlled engine I have deactivated the EGR on has ran smoother so I'm not going to tell you to not remove it but I'm also not telling you to violate and state or federal emissions laws. Depending on your state and year of your car it may now be exempt. If it is a newer car with an ECM and sensors then it will throw codes and can effect other systems. Now as a final thought, I have known people to use a vented fuel tank cap and block off the tank vent line. Then remove the vapor canister, the vacuum lines to the carb, remove the thermal switch and plug the hole on the intake and remove the T in the pcv hose. This essentially puts your engine back to a pre vapor canister configuration. I'm not telling you to do this but it could be done without effecting drivability at all. There is such a small amount of fuel vapor introduced to the engine that carb settings should not even miss it.

Tom
 

stevolwevol

Well-known member
Joined
May 28, 2015
Messages
239
Location
Michigan
Corvette
1977 light blue
Before I red your post I replaced the thermal switch with a brass plug, and plugged the vacuum hose that goes to the canister. I drove it about 15 miles, and everything seemed ok. I could put the thermal switch back in if I have issues. My idle seemed to be lower, Maybe I had a small vacuum leak in one of lines, but it's warmer today than it has been. Thanks for the advise. Steve
 

ctmccloskey

New member
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Aug 5, 2017
Messages
2
Location
Fairfax
Corvette
1968 BB,4 spd. Convert. C3, 1988 Auto. Coupe
Removing the EGR can be a big mistake on a lot of Corvettes.

They make the engine run cooler and reduce the likelihood of detonation. The EGR to be properly removed might help your engine but it requires a Software update on the later models.

Disabling the EGR is not done by stopping the vacuum coming from the EGR Vacuum Solenoid. On the C4's with their L98 engine's the EGR is very important or you will need to run premium fuel to stop the pinging and that won't even do a good job. I am a big believer in leaving the EGR systems alone on my Corvettes.

We recently witnessed a guy driving his new to him Corvette up the mountains and he heard pinging a good deal of the way. His EGR was disabled or broken and upon fixing it the pinging went away on the interstates.

Be Well and Stay Well!
 

Hib Halverson

Technical Writer for Internet & Print Media
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CenCoast CA
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71 04 12 19
Some older engines with EGR may detonate at part throttle without it.
 

stevolwevol

Well-known member
Joined
May 28, 2015
Messages
239
Location
Michigan
Corvette
1977 light blue
Well, I have had the EGR delete for a while now, and nothing bad has happened. I really miss the tangled mess of vacuum lines, but I'll get over it. No pinging either, part throttle, or full. My other Vette I replaced the intake with a Edlebrock performer that came EGR delete. There isn't a place for the EGR as you probably know. It also runs great. So everything works, no issues with getting fuel, less vacuum lines, no exhaust being fed into the carb, not pinging as I already mentioned. Glad I did it. Thanks everyone for your input.
 

gmjunkie

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Joined
Nov 11, 2004
Messages
4,519
Location
Old Fort NC/Vero Beach FL
Corvette
03 Z-51,78 L82 Coupe
May just be me, If the General put it on there,I put it back!:thumb
If it don't work properly,I fix it!~~!:D

Just my nickles worth,2cents is a thing of the past!:L
 

stevolwevol

Well-known member
Joined
May 28, 2015
Messages
239
Location
Michigan
Corvette
1977 light blue
May just be me, If the General put it on there,I put it back!:thumb
If it don't work properly,I fix it!~~!:D

Just my nickles worth,2cents is a thing of the past!:L
I like it better with the junk off, runs just fine, so why clutter up the engine? (that was a rhetorical question). I detest that early emissions junk mandated by bureaucrats.
 

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