I have a 1994 Z28 with an automatic transmission. I get an intermittent service light and a P0029 code is referenced. When this happens the car seems shift harshly. 1994 should be OBD - I, right? I thought P0029 is an OBD-II code? -- P0029 Exhaust Valve Control Solenoid Circuit Range/Performance (Bank 2)

Does this refer to an engine problem or transmission? If it's an engine problem why would this affect the transmission shifting? I could see a TPS sensor doing that, but what does this refer to, exactly. Wouldn't it be related to a shift solenoid problem since it's a 4L60E transmission?

Googling only brings up posts that list the codes--nothing specific on how to resolve the issue. If this is a valid code, what can I do to fix the problem? Is there a specific solenoid I need to look at?

Thanks in advance for the help!

 

Your our is OBD1 and does not generate P codes. If the scanner shows a P code it is not a OBDI scanner or it has a problem. The closest thing to your code is DCT 29.
DTC 29 refers to the AIR pump control circuit. The PCM sees a voltage other than 12 V or less than 1 V on the control lead going to the AIR pump relay. When the PCM does not see the expected condition it disables the lead to prevent damage to the PCM and sets the trouble code. Look for a bad AIR pump relay, a short or ground on the control lead, blown fuse #7 (under hood panel), or a defective PCM (unlikely). The control lead is the Brown wire going from pin A14 on the PCM to pin E2 on the relay.
Rough shifting could be due to the PCM going on limp mode. Check to see if there are any other codes, and try a different scanner.