JFC

Hi, so it's been determined that this is the cause of my check engine light coming on occasionally. Does anyone know where I can get one of these? I would consider new or used at this point. Also, assuming this part needs to be replaced, how bad would it be to just run it like it is without replacing it? Let me know. Thanks, Jay

toptechx6

You will have more success if you specify the year of your car or at least fill out your profile.

JFC

You're right. I have an '85 C4 all stock L98

Aqualoo

I don't know if my year is similar, a 92'. But on my Florida to Colorado roadtrip my EGR threw a code so I got off the highway stopped at a Wal-Mart for some brake cleaner. Cleaned up the selenoid, pulled the ECM fuse to reset the codes and everything was fine after that.

Cliff Harris

There are several pieces in this puzzle.

The ECM sends a signal to the EGR solenoid mounted on the thermostat housing. There is a plastic vacuum line from the bottom of the throttle body that connects to the EGR solenoid. When the EGR solenoid is energized it feeds the vacuum from the throttle body to the EGR valve, which opens and feeds exhaust gas into the plenum. The exhaust gas comes from the passenger side exhaust manifold and goes through the EGR tube to the intake manifold. Mounted in the EGR tube is an EGR temperature switch. When the EGR switch gets hot it grounds a wire to the ECM so the ECM knows that the EGR system is working. If the ECM does not see this signal when it commands EGR then it will set an error code 32.

The main points of failure are the EGR solenoid, EGR valve, vacuum lines and the EGR temperature switch. All of these work together and if any one fails then the system doesn't work.

It is very common for the EGR temperature switch to fail. These were not available for a couple of years but about a year ago a company started making them. They are now available from all the usual Corvette parts vendors.

If the EGR solenoid or vacuum lines are bad then the EGR valve can freeze in the open or closed position. If in the open position, idle will be rough. If in the closed position, error code 32 will be set. I know that the EGR solenoids were not available as of a couple of years ago. I do not know if that has changed. It is possible to use a similar EGR solenoid from another car but the mounting bracket will be wrong.

The vacuum from the throttle body is PORTED vacuum, so there is little or no vacuum at idle. I just found recently that my plastic vacuum line from the EGR solenoid to the EGR valve was melted and there was a large hole in it. I don't know how that happened. The plastic is not very robust and it doesn't take much to melt it.

JFC

Thanks Cliff. When we changed injectors last weekend one of the three or four prong connectors for the vacuum line lost it's colored ring that goes around where the two pieces connect. We used a bunch of silicone around the connection. The only indication that there is any problem is that after about 10 to 15 minutes on the freeway the check engine light comes on. Otherwise around town there is no problem. So I plan to drive it from St.Paul to Colorado Springs a week from Monday. Can I still drive it in it's current condition without it being a bigger problem? Let me know your thoughts. Thanks, Jay

toptechx6

Rock Auto lists a vacuum solenoid for the 85 Corvette if you can't find one locally.

http://www.rockauto.com/

Cliff Harris

That's the classic symptom of an EGR system problem. The ECM only does the test during cruising so that's when you see it.

In my case the EGR solenoid went bad so it wasn't opening the EGR valve, which got carboned up and froze in the closed position.

The EGR system reduces combustion temperatures and many people remove it, so it appears that it is safe to drive with it not working. I don't think your pistons or heads will melt.

gerardvg

Yes i can confirm there is no problem having the EGR not operating.
I ran my vette with the EGR disabled for many years, i only reconnected it a few months ago and yes it still worked.
I was getting annoyed with the check engine light on long drives, is nice i can drive without any codes now