Hey, I've spent many a long hour over the last few months scouring Usenet, the Web, and my Haynes (painful, yes) manual, trying to figure out how to fix the miss I have in my V6 3.4L 1995 Camaro, now I come to you for some help.
Let me first tell you what I've tried already:
Replaced spark plugs and wires Replaced 02 sensors Installed new intake gasket and resealed manifold Replaced IAC Cleaned throttle body
Here's the problem: The car starts up, but when it's idling at 900 RPM's, it'll violently shake/shudder and immediately drop (like a burp) like -50 to -75 RPMS from where it was idling, seemingly "catch" itself and recorrect itself back to 900 RPM's. There is a short delay between each hiccuup; but, it seems pretty consistent when in idle. From low RPM accelaration it feels sluggish.
I have had the car into a dealer, for the plugs and 02 senors, they didn't uncover any engine codes when they had it hooked up. I'm pretty sure the ECM is working, since after I put together my manifold I forget to hookup the MAF sensor and the check engine light went on. If I unplug any device, IAC comes to mind for this test, the check engine light will come on.
I was there when they hooked up a scan tool and it seemed like all the sensors were putting out "good" results. I haven't run a compression test on the engine, should that be my first move now?
Based on my most recent research, it seems like maybe my EGR is stuck open; however, in the 3.4L GM cars these are digital. Is it possible my EGR is broken and not sending an error code? Also, is it worthwhile for me to pull it off, look for the valve, and then, assuming it is dirty, try to "de-carbon" the valve and associated passageways?
Otherwise, what else should I be looking at in my car? I don't have a lot of experience hunting vacuum leaks in hoses, should I be looking for that first of all? Is the problem I have a "miss" or is just an idling problem? Got any helpful hints or candid advice? Please post or email me back at (nospam) snipped-for-privacy@ncf.edu.