I have a 2002 Z28 with a cam and AFR 205's among other things. Recently the car has been acting strange. It has always seemed to need a few minutes to warm up to operating temp before it ran smoothly after the heads went on. Recently, the idle has sounded a bit weird, and it will shudder, and not want to accelerate when I try to give it gas, if not warmed up completely. It feels just like a miss, or something. One day it was hesitating and shuddering even after being completely warm. I changed the fuel filter, and plugs and it seemed to help it a lot. Also, the idle will occasionally dip down to ~500 rpm and surge back up to normal. (only happened two or three times) I put it on the Tech2 at work, and I didnt have any misfiring happening. I did remove some type of "lean fuel trim" code, or something worded similarly though. Would this be a clue?

Once it is warmed up completely, it seems to run fine though. But it seems to take a long while for the engine to not shudder when I give it gas during the warm up. What might be the cause of this happening? Have any of you guys had a similar problem? I've been told by one tech at my work that it could possibly be an O2 sensor, and another tech told me thats most likely not the problem. I was also told to check my fuel pressure while cold, and then when warm. I'm not sure where to look next...

What would be a good way to diagnose this problem?

Have any of you experienced something similar?

Where would you look next?

Ant input or help would be greatly appreciated, b/c when my car isnt acting right, it drives me completely nuts and its all I can concentrate on.

 

anyone?

 

I was thinking 02 sensors as well....