please help. 96 monte carlo z34 no power,bogs under accel

[evman100]

Hi and thanks in advance for any advice you can offer. I have a 96 mc z34 with 134000 on the odo, but who knows how many miles and the 3rd factory engine and transmission. The car will rev freely when not in gear. In gear under load it will not get out of its own way. It bogs, misses and makes a hissing sound that seems as if it is coming back through the intake portion(can't get it to replicate with foot on break in gear while revving). If I feather the trottle it will get up to speed but with lots of difficulty. I have had a similar problem in the past with the problem being the ignition wires. I changed the plugs and wires, hunted down a few small vacuum leaks and still have the same problem, had western auto plug in their scan tool and got back an "unspecified miss" and a "secondary air injection" trouble code. Any thoughts anyone?

[Jaysin]

This seems almost exactly what my Monte was doing after I built the engine. Good idle and rev in park but when I put it in gear and tried to go it seemed like it didn't want to. Sounded horrible and hissed under the hood and under the car. Turned out my cat was clogged. I cut that bad boy out and it was like new. (Except the damn exhaust leaks. Those clamps suck. Gonna weld it up in the summer) I'm not saying this is it but it is worth looking at.

Good luck, Jay

[Juglenaut]

Check the neutral safety switch. However a bad IAC in your case may cause a secondary air injection error, and the other way to...A bad secondary can cause the IAC to fail but not fault. In fact there is not direct code for an IAC on this year. Check the air injection relay and the air injection pump, The IAC runs off the pump's red wire.

[z34phoenix]

with that many miles, did you change the 02 sensor? i have gotten an intermittant secondary air injection code P 0172 IIRC and i was told that it could be the O2. that is my next project.