jocamino

Hey I'm replacing the heads and was wondering if I use a EGR valve block off plate Will I have to have it tuned?

Injuneer

There are two possible codes for the EGR system. DTC 26 (Quad Drive Module #1 - 93 only) will set if you disconnect the EGR vacuum solenoid. The code can be eliminated with w resistor. I'd use at least 1,000 ohms. If you don't delete the solenoid, it's not a problem.

The second code is DTC 32. This code sets when the ECM cycles the EGR system, and looks for the correct change in MAP (manifold absolute pressure). IF it doesn't see the MAP change, due to exhaust gas flow, it sets the code. For the OBD-1 cars, the diagnostic is not very sensitive, and maybe 1/2 of the deletes do not set this code. Drive it, and if it sets, you'll need to have the code deleted in the tune. There is a minor impact on ignition timing related to EGR, but nothing to worry about.

Are you installing ported heads? If so, you are going to want a tune, because it will change the voumetric efficiency (VE), and in your 93, controlled by speed-density, this is a critical table.

And, finally, EGR has no effect on performance. Not used at idle, not used over 3,500 RPM, not used at WOT. Can be a problem if the valve sticks open though.

jocamino

Thanks for info. I'm just putting stock casting on it. Have a crack in #3 cylinder and its for my 17 yr old. But thanks again.