EGR Solenoid
Thread Starter
Burning Brakes
Joined: Jan 2017
Posts: 961
Likes: 237
From: Diamondhead Mississippi
St. Jude Donor '17-'18-'19-'20-'21-'22
EGR Solenoid
I have an 88 and was in the process of replacing the diaphragm on my FPR when i noticed that the vacuum line going to the EGR solenoid from the EGR is kinked. I don't have any codes and other than a higher than normal idle the car seems to run fine. I planned on looking for bad vacuum lines while i had the plenum off that may have been causing the idle issue. I have a new EGR valve and was going to replace it also but am wondering what issues this kinked line may have caused. With no vacuum to the EGR does it stay open or closed?
Racer
Joined: Jun 2017
Posts: 343
Likes: 18
From: Newport News VA
I have an 88 and was in the process of replacing the diaphragm on my FPR when i noticed that the vacuum line going to the EGR solenoid from the EGR is kinked. I don't have any codes and other than a higher than normal idle the car seems to run fine. I planned on looking for bad vacuum lines while i had the plenum off that may have been causing the idle issue. I have a new EGR valve and was going to replace it also but am wondering what issues this kinked line may have caused. With no vacuum to the EGR does it stay open or closed?
It should Idle fine since exhaust gas isn't being recirculated. What you might see is higher head/combustion chamber temps and possible increased detonation, especially if you are running a stock L98 cam. Many delete the EGR function and don't experience issues, but it is a case by case basis it seems.
Safety Car
Joined: Aug 2009
Posts: 3,751
Likes: 276
From: Melbourne, Victoria, Australia
I have an 88 and was in the process of replacing the diaphragm on my FPR when i noticed that the vacuum line going to the EGR solenoid from the EGR is kinked. I don't have any codes and other than a higher than normal idle the car seems to run fine. I planned on looking for bad vacuum lines while i had the plenum off that may have been causing the idle issue. I have a new EGR valve and was going to replace it also but am wondering what issues this kinked line may have caused. With no vacuum to the EGR does it stay open or closed?
If the EGR valve sticks open, stalling rough or higher idle can result.
Safety Car
Joined: May 2001
Posts: 4,759
Likes: 1,647
From: Fairfax Virginia
My 1988 Coupe failed the state emissions test one day and that was how I learned I had a bad EGR. The test showed the NOX was off the chart so I replaced my EGR. My idle had been a bit rough but I knew I had a bad injector and wrote it off as nothing unusual.
What I found was that the Vacuum Solenoid that controls the EGR was not getting any vacuum so the valve never opened up. After connecting the solenoid back up to vacuum then I found the solenoid was faulty as well.
When I disassembled the intake system I found the EGR passages were plugged with hard carbon. I have no idea how the carbon formed but it was a pain in the butt to clean out the EGR parts.
If your hose is kinked going to the solenoid then you might want to take a longer look at the entire EGR system. You might find plugged passages like I did from an EGR that was not working for a while. There are many who recommend removing the EGR system as opposed to fixing it. I find that keeping this engine close to stock and everything functional that it is a reliable car to use and own.
Good Luck with your Corvette and your EGR system!
What I found was that the Vacuum Solenoid that controls the EGR was not getting any vacuum so the valve never opened up. After connecting the solenoid back up to vacuum then I found the solenoid was faulty as well.
When I disassembled the intake system I found the EGR passages were plugged with hard carbon. I have no idea how the carbon formed but it was a pain in the butt to clean out the EGR parts.
If your hose is kinked going to the solenoid then you might want to take a longer look at the entire EGR system. You might find plugged passages like I did from an EGR that was not working for a while. There are many who recommend removing the EGR system as opposed to fixing it. I find that keeping this engine close to stock and everything functional that it is a reliable car to use and own.
Good Luck with your Corvette and your EGR system!
Thread Starter
Burning Brakes
Joined: Jan 2017
Posts: 961
Likes: 237
From: Diamondhead Mississippi
St. Jude Donor '17-'18-'19-'20-'21-'22
I found that not only was the vacuum line kinked but it had a hole in it between the kink and the vacuum port. I tested the old EGR and it was definitely bad. I replaced it fixed the hose and put it all back together. I still have a vacuum leak somewhere else that I have to track down but ran out of hours yesterday. I am hoping I don't have a leak between the plenum and runners when I put that back together.
Race Director
Joined: Aug 2000
Posts: 11,470
Likes: 764
I found that not only was the vacuum line kinked but it had a hole in it between the kink and the vacuum port. I tested the old EGR and it was definitely bad. I replaced it fixed the hose and put it all back together. I still have a vacuum leak somewhere else that I have to track down but ran out of hours yesterday. I am hoping I don't have a leak between the plenum and runners when I put that back together.
i replaced everything on my 85 - engine vacuum, fuel vapor emissions and associated vacuum, and even windshield wiper fluid lines - everything! i swear, my idle is much smoother, low RPM throttle response improved, and in general, everything just seems better. some of my tubing was so cracked and dry rotted, it's a wonder it retained the properties of rubber.
