I am putting a 355 in an orginally 305 carburated 86 iroc-z but the new 355 does not have the exhaust gas ports in the heads so from what i understand i can't use the EGR? So if i delete the EGR is it going to throw a trouble code?...I want to try to keep the cc carb and most of the emissions but i do not want to have to buy new heads...will i be okay if i delete it or is my computer going to have problems?Thanks

 

If you leave the EGR vacuum control solenoid connected but disconnect the vacuum lines, the ECM won't know the EGR is not there. So you wouldn't see a fault light.

 

my 92 tbi running the 7747 ecm will still give an egr code if I cruise on the high way for about 20 -30 min that is with solenoid still plugged in

 

That is interesting, I wonder how the computer knows the EGR Valve isn't there or working. What code do you get?

 

This may not be the same, but on the newer vehicles that are OBD2 compliant, the PCM looks at the O2 readings to see if the EGR valve opens. It should go slightly lean as the valve is commanded open.

Now as for your carbed car, I don't think the computer is smart enough to know if the EGR works. My 84 has had the vacuum line to it dry rotted off it for the past few years (Hence not working) and I've had no problems, although that could be contributing to my high speed lean-out issue.... Oh well, TPI coming really soon anyway, so I don't really need to worry about it!

 

But would that be a good idea without re-calibrating the prom?

Does'nt the GM-software consider "EGR ON" when handling the spark advance?

 

I don't know if it's a good idea or not really. But so long as the engine isn't routinely retarding itself due to knocking, or running lean or rich I'm not sure it would be a problem.

I do think the whole idea of recirculting dirty exhaust rubbish into the inlet system is cruelty to engines.

 

One thing could be a lower combustion temprature at cruise.

 

YES,
Depending on application, some calibrations add alot of advance if the ecm THINKS the EGR is on.

 

thats a big negative there fella. the idea here being an average value over time, but to your credit, short term fuel trim is figgered in on occasion, too.(MAF) GMspeak, that is. sometimes Lazy o2=EGR CODE

The EGR Flow Rate Diagnostic uses changes in the Manifold Absolute Pressure (MAP) during actuation of the EGR valve to determine how effectively the EGR system is operating. The EGR Flow Rate Diagnostic forces the EGR valve open during a closed throttle deceleration or forces the EGR valve closed during a steady state cruise. Selection of the cruise test or the deceleration test is determined by the Diagnostic calibration.
A complete test of EGR valve flow rate is the average of MAP changes over several valve actuations. The results of each single test are averaged to minimize variation and avoid misdiagnosis. Failure of the EGR valve is indicated when this averaged value exceeds a calibrated fail value.
Usually only one test is run per ignition cycle. The following are two occasions where multiple tests are run during a given ignition cycle:
The Fast Initial Response (FIR) feature is enabled after a code clear or battery disconnect.
The Rapid Step Response (RSR) feature is enabled due to an abrupt change in the measured flow rate.
This diagnostic is intrusive in that it opens the EGR valve when it is normally closed, or vice versa. This may result in a perceptible change in engine speed on automatic transmission equipped vehicles during the deceleration test. Operation of the vehicle should not be affected, but you may notice the engine speed fluctuation on vehicles equipped with tachometers.