85 Z51 Auto fighting an extremely rough hunting idle. Haven't thrown parts at it but have replaced the IAC and the TPS with no noticeable effect. Throws a code 32 frequently. EGR will not hold vacuum. Being that, would the EGR not moving be the same as a block off plate? Would that disqualify it as a poor idle source? Car runs well off of idle and is getting normal, 16+ mpg. Compression 150, vacuum 20 inch, fuel pressure 40 psi, all new tuneup items including a coil (replaced before problem). Scan tool shows nothing obvious. Have checked lots of other components all operating within specs.

I have much more money in this than I had expected. Needs driveshaft u-joints $350 at the shop as I'm not doing in my drive or before I get it running better anyway. Ready to sell, even contacted PO to see if he wanted it back and took sales pics. It is running with a park idle of 950 rpm and hunting between 700-850 in drive. Not sure if you would consider that "idle". Suggestions appreciated.

TIA,

Joe K

 

I have had those problems. Don't be fooled by the neg vacume (?) EGR it will not hold a vacume , because the unit has extra passages inside. That is probably why my 85 unit was 140.00
when I bought it. Code 32 is egr failure, at start or at cruising. Clean the 2 switch connectors at the front of the engine for egr. Clean(with electric cleaner from can not wire brush) the egr solenoid connector, and make sure there is no leak from the vacuum lines in the said egr system. Make sure your egr temp connector is good and clean. You can tell if you have a miss by noticing the fuel mpg instant wont go back to 0 when you stop, and idle up and down surge. Mine idled all over until I discovered that my injector plug was corroded.
My egr code came back last week and I recleaned the connectors and unplugged the battery(to reset a must do on 85 not just undo the ecm plug) and no code anymore.
Good Luck!

 

First, I know very little specific to 1985 Corvettes and their unique systems.

Sounds like there must be a vacuum leak somewhere. The EGR can usually be seen moving when vacuum is applied to the valve. My EGR failed and caused my car to fail it's emissions test. After removing it and ALL the carbon that was in the passageways for the EGR I found that my EGR Vacuum Solenoid had failed and started the ball rolling downhill. With the EGR replaced and working I had to replace the vacuum hoses to be sure to get a good solid vacuum signal to the EGR solenoid. It is important to keep the vacuum system working normally, had I known about the bad solenoid I could have saved a lot of money and time taking the top of the intake off the car.

The carbon was hard as a rock and was removed with a sand blaster, a lot of work. I used carburetor cleaner to soften the carbon as that helps get rid of it. I also broke out my engine brush set and used it to clean out the passageways.

The only thing that changed when my EGR went bad was the EGR tube in the engine compartment that has the silver cover on it melted the cover material. I should have wondered what had changed to cause that to happen.

Too old too Soon
Too Smart too late

Best regards,
Chris