ok, here's the scenario. I've searched a bit, but haven't really found any threads that adressed my situation exactly, so I thought I could go ahead and ask.

I am in the process of installing MAC midlengths on my 94 Z (OBDI). Due to frustration with the fitment of the egr pipe to the passenger side header, I have decided to block off the egr system entirely. I have the blockoff plates, and will plug the vacuum line to the intake.

From what I have read, as long as I don't unplug the egr solenoid, I should not throw a code with my OBDI computer.

My question is, what impact will this have on the sniffer test? I have read that the egr system lowers NOx emissions under a load in higher gears.

During my header install, I confirmed my earlier suspicions that the previous owner had hollowed out the cat. My car still passed the sniffer last time I got inspected. I am going to put a carsound cat on with my new setup.

Should the addition of the cat more than make up for the loss of the egr for the NOx emissions?

I'm hoping that Injuneer will respond to this thread as I noticed in some of his previous posts that he commented frequently on what the egr system does to effect emissions, and thought that he might know how all this might work together.

Thanks to all

 

Oh, and I realize that it won't pass visual technically, but I'll take my chances that the guy at the shop won't notice or care, but I'd like to be within the actual limits for the pollutants.

Also, would getting new O2 sensors help the car run any cleaner? I have no idea how old the ones on there are.

 

I would think that having a cat - when you had none before - would have a much larger affect on reducing emissions of NOx than the EGR system. How much the EGR affects the emissions level in a rolling dyno test is probably somewhat dependant on what your State's "drive cycle" is. Not evryone uses I/M240.

The 93-95 OBD-I PCM has a diagnostic check for EGR circulation. The test just doesn't seem as sensitive as the one in the OBD-II setups. But it isn't impossible to get an EGR code on OBD-I.... maybe 90% never throw a code, and the other 10% do.

 

My '94 just threw a code for EGR recirc the other week. I have non-emissions long tube. The egr solenoid is still plugged in.

 

In the event that it does throw a code, are OBDI PCM's capable of having that functionality "turned off"? Without having to get the plug-in test that OBDII cars get here in Texas, I would guess that there would be no way to tell if the computer had been monkeyed with.

Thanks again.