I've recently run into a problem with the 3.4 in my dd Firebird. The shop I entrust some of my repairs to told me that the camshaft is bent causing the engine to miss at higher rpms and I need a rebuild.

I just did new plugs and wires and the car idles beautifully and drives fine below 2000 rpm but when I accelerate above about 2500 rpm there is a rapid backfiring type sound that comes out of what sounds like the CAI. I'm wondering if the real problem is a bad or bad injectors? The injectors have 140k on them and the engine has 56k (the original crapped out at 86k so I installed a new GM crate 3.4). I'm thinking the motor is still relatively new to have a camshaft problem but the injectors if plugged/ clogged could cause a higher rpm problem since their workload increases with the RPM's.

Anyone have some sound advice or ideas?

Should I buy a new set of injectors or could something else be at play here?

 

Let me try to simplify what I'm experiencing.

While the car is stationary I can redline the engine without issue.

While under load the rpm's struggle to climb above 2500 RPM.

Would this be indicative of a fuel problem?

 

clogged cat maybe

 

No Cat.