EGR Valve

[Justin Fleming]

So I am sorting out issues on the 90 k5 that I just brought home. The truck seems to run real good and strong. I decided to take the air cleaner off to look at things. What I notice is there is a electronic deive with a vaccum line which looks like it should be going to the egr but they have it unplugged and plugged the vaccum line. What are the thoughts here do I need to get the EGR back in the system? Was it eliminated do to headers etc?

The truck has headers on it and I assume they have eliminate a bunch of the emission air pump type stuff. I assume it would have been on this truck not really sure though...but there are no signs of it at this time. It has true dual exhaust not cats O2 sensor is in the headers...

 

[Mastiff]

I'm no expert since my truck is older, but 1990 is factory TBI and the computer controls the EGR. Unless the computer "chip" was modified to eliminate the EGR, I think you'd be worse off for messing with it (should leave it hooked up).

I'm not sure if 1990 still had AIR, but that seems less important from a performance perspective anyway.

 

[Justin Fleming]

I'm no expert since my truck is older, but 1990 is factory TBI and the computer controls the EGR. Unless the computer "chip" was modified to eliminate the EGR, I think you'd be worse off for messing with it (should leave it hooked up).

I'm not sure if 1990 still had AIR, but that seems less important from a performance perspective anyway.

Any other thoughts or suggestions out there...

 

[Burbdood 74]

If you don't run an EGR you might get an occasional code 32 which is "fault at EGR diagnostic switch". I have no earthly idea what it means but it does get annoying seeing that light come on.

My guess is the previous owner had a surging idle due to a faulty EGR and instead of replacing it, they just eliminated it altogether. Having a functioning EGR doesn't rob power, it helps cool the cylinders down while you drive and it keeps the truck from pinging when you're hard on the throttle, so I would buy another EGR, hook up the EGR solenoid and drive it around.

 

[Justin Fleming]

If you don't run an EGR you might get an occasional code 32 which is "fault at EGR diagnostic switch". I have no earthly idea what it means but it does get annoying seeing that light come on.

My guess is the previous owner had a surging idle due to a faulty EGR and instead of replacing it, they just eliminated it altogether. Having a functioning EGR doesn't rob power, it helps cool the cylinders down while you drive and it keeps the truck from pinging when you're hard on the throttle, so I would buy another EGR, hook up the EGR solenoid and drive it around.

Thanks for the good advise....

 

[dyeager535]

Lack of EGR should throw a code, but unlike some other codes, will not affect how the engine runs otherwise. Of course, if your CEL is on because of a bad EGR, and you ignore the light because of it, and something else goes wrong, you may have screwed yourself.

Really not going to matter one way or the other if it's hooked up (IMO) in regards to performance as there is no concrete evidence/testing anyone apparently has access to that shows a power gain or loss with it, nor affect on mileage. Pretty common for them to "crud up" from carbon, but that's normally a pretty easy fix.

With a carburetor, removing the EGR will show a lean spot in cruise, but with EFI, the O2 (during cruise) is going to modify fueling to maintain the mixture it wants to see.