So I have a 91 gta l98, and the car is mint besides the engine work needed. Ok when I first got the car it drove horrible, almost like it had a vacuum leak so I started searching around for a leak of some sort and found that the egr hose was completely disconnected, so I plugged that in and the car ran like a whole new animal for about a week, it didnt feel as strong as it could be, but much better that what it did before. So, thursday comes around and I cruise it down the the local track to see what it'll do so I can kinda see how bad its running. It managed a 15.6 at 92 spinning pretty good, but on the way home from the track, the car all of a sudden starts surging and pretty much just running like it was before, If you roll into the trottle it seems to run ok, but if punch it, it just falls on its face, it doesnt want to pull past like 3k rpm, its weird, however I was getting an engine code so I read it and it came out to be an egr issue. So I decided to just block it off. So far I have put all new plugs, wires, cap, rotor, and msd coil, I have cleaned the IAC valve and checked the voltage at the TPS. The car has no cat, it has been straight piped by the previous owner. I have cleaned the throttle body the best I could. And there is currently no engine lights and I looked over the engine very well and couldnt see any other unattached vacuum hoses? I'm really tired of dealing with this and just want to enjoy my car. Please help.

 

Hmmm well just blocking off the egr isnt exactly going to help you since the ecm will still be looking for it.If you get a chip burned to not rely on egr then that might help aswell..or just get a new egr.Also alot of ppl dont check the actuall condition of the vacuum lines.Just because they are hooked up doesnt mean they wont leak or have pin holes and cracks in them.Another thing I might suggest is check the o2 sensor...who knows how bad the previous owner had the car running with the egr not connected and your readings are all over the map which will throw timing off and not perform at all.

 

There is no connection to the EGR on a '730 ECM, it can't "look for it"

 

Correct me if I am wrong, but isn't there an egr solenoid that the ecm controls?

Check the egr valve, basically with the valve in your hand push the diaphram up and then block the air inlet with you finger. let go of the diapharam and see if it holds a vaccuum. once you let go of the inlet with your finger it should suck in air. that mean the egr is functional. make sure that there is no carbon buildup on the egr as well.

 

If you push up on the EGR valve and it doesn't move, you possibly have it stuck open and can act like a vacuum leak.

 

The 730 ecm does have an EGR solenoid and it does run a diagnostic on it. Stock setup is set for a diagnostic at 30mph. If it does not find the solenoid it will throw a code.
I'm not sure how the test is conducted. You may be able to leave the solenoid and remove the valve. A search should give you that answer.