indeed, ERG dumps inert exhaust gasses back in the combustion chamber, reducing volume thereby reducing combustion temps, but this is only to reduce NOx, and nothing else to do with regulating engine temps.

There's very specific criteria for EGR to be enabled.

On heavy load, high rpm, ERG stays disabled.. Hard driving will never invoke the EGR, so not having 'EGR' will not cause a 'melted piston', nor shorten engine life. Some other reason there.

And a cam overlap can even eliminate the need for a dedicated EGR system.

my EGR tube is blocked off and I can predict when CEL-32 pops on, which only is when engine at operating temp, constant light load, easy highway driving for about 15 minutes.. and then the CEL turns off when engine is turned off every time. I will tune this out, eventually.

Anyone follow that VW diesel emissions scandal? The 'defeat-device' was actually code to disable EGR. Some VW engineers and top brass were perfectly fine disabling EGR in 11 million TDIs, those engines ran great lol..

"The software sensed when the car was being tested and then activated equipment that reduced emissions, United States officials said. But the software turned the equipment down during regular driving, increasing emissions far above legal limits, most likely to save fuel or to improve the car’s torque and acceleration. The software was modified to adjust components such as catalytic converters or valves used to recycle some of the exhaust gasses." (that translates to ERG Valve)

 

I'll bite. Besides emissions testing, what is the ROI? How much more relevant will the O2 sensor reading be? How much benefit will be seen from the lowered combustion temp? Isn't pre ignition guarded against by the knock sensor?

 

I also have an 85 4+3. I kept getting code 32 also while highway (easy 55mph + in overdrive) for 30 minutes or so. It never caused any problems that I could see. Just annoying to see that dreaded yellow CHECK ENGINE light! So I replaced the EGR valve and the sensor that screws into the EGR mounting base. Note that the EGR for manual transmissions is different from the EGR for automatic transmissions. The problem still occurred! The last thing to replace was the EGR solenoid switch. That finally corrected my problem. That solenoid is a one year only part design for the 1985 year. I could not find one anywhere. I had to improvise one from another year to mount it correctly.

 

Before ethanol I was pulling 30-31mpg on the drive along I-80 from SE NY to NY OH; now it's 29-30mpg.

 

Ethanol does have a lower energy content