I have a 1997 Z28 with an OBD1 pcm and my RPMS are surging like crazy, first when I start the car it’ll idle about 1000 for a bit then eventually it’ll start surging from 500-1500, and even stall out too occasionally. This is a H/C car but has not been tuned yet. Fuel pressure is holding up and I have not found any vacuum leaks as of now. I currently have my O2s unplugged and MAF disabled, does that sound like it would be my issue? Also to mention my IAC counts go from around 70 at startup then work their way up to 160 if that could be my issue too. Thanks!

 

Here is a video of what EEHack is reading and what the surging looks like:

 

What are the cam specs? What size are the injectors? Why did you disconnect the MAF and O2’s?

With no tune, disabling things, you've totally destroyed the PCM's ability to control the engine. By disconnecting the MAF sensor you've forced the PCM into speed density. Speed density relies heavily on the MAP sensor reading. Throw in cam surge and the MAP is all over the place.

By scanning the camera around so fast you eliminated the ability to watch the critical readings like MAP.

 

It’s requested by my tuner to leave the MAF unplugged as well as the O2 sensors. Cam specs are 222/230 112 LSA, and LE1 heads, injectors are 36LB which has been tuned in.

 

I just went back and looked at your two previous threads. In both of them I tried to help you, and you never followed up.

”hasn’t been tuned yet”….. or “36LB which has been tuned in” ? ? ?

You're making this difficult.

 

sorry in regards to my previous threads my car ended up dropping a valve so I had to source a whole new block. But sorry I meant it’s tuned for injectors but not for the cam/heads.

 

Honestly the cam is just as big an impact for the tune as the injectors. If your tuner is telling you to leave your O2 and MAF disconnected, you may want to look for another tuner. Have you checked out Brandon Strong, owner of Strong Speed Works?