I'm having trouble understanding what's going on with my 95 z28. First off is having a hard time accelerating and is stuttering and has a weird rattle at low rpms till about 2-2500. So I got the codes ran a while ago and had code 32, I changed the EGR valve a few days ago and now I'm getting code 32 still and also codes 29 and 48. I read that 29 is probably just the air pump fuse so I checked it and sure enough it was blown so I swapped it. Code 48 is maf so I tried the unplugging trick but no difference. What else could I be getting code 32 for? Why is my car stuttering? Also I have a weird sound coming from the rear right at low speeds (especially noticable in parking lots) and when I get on it from a start or the 1st to 2nd shift there's a hard clunk from the right rear as well.

 

If you have an active DTC 48 for the MAF sensor, the PCM has defaulted to running in speed-density mode, calculating Mass air flow from RPM, MAP, and IAT sensors. If this is the case, the “unplugging trick” isn’t going to change the way the engine runs. There are 3 wires in the MAF connector:

pink = 12 volt supply

black = ground

yellow = variable frequency signal to PCM

Key on, engine running or off, connector off the MAF sensor, check for 12 volts between the pink wire and the black wire. If you have 12 volts, and the connector pins are undamaged and free of corrosion, the MAF sensor is probably faulty. If your multi-meter has a frequency scale (Herz, or Hz), reconnect the harness, and check the frequency between the yellow wire and ground. At idle you should see 2,000-2,500 Hz. Alternatively, borrow a known good MAF sensor. Clear the codes (pull the PCM BAT fuse in the under hood box for 30-seconds), and run the engine with the known good MAF sensor to see if the code comes back.

Is the engine stock or modified? If modified, who tuned it?

DTC 32 for the EGR system shouldn’t cause stuttering, unless the EGR valve is stuck open. Does the engine idle smoothly? If the EGR valve is stuck open, the idle will be very rough, to the point of almost stalling? The code can also be set by a stuck EGR vacuum solenoid, leaking vacuum lines between the intake manifold and EGR valve, plugged passages in the intake manifold, faulty MAP sensor.

Need a better description than “weird sound” for the problem at the right rear? Does it sound like the brake pads rubbing a rotor, the screech for the little metal finger on the brake pad rubbing the rotor to tell you the pads are worn out, a cyclic bearing or worn U-joint noise, etc.?