Ok so I have a 01 3.8 MT Camaro. I was driving about 20 minutes ago... and it's NEVER happened before... but I went to accelerate onto the freeway, and my car started to shudder really bad. After messing with the problem while driving... I figured out that it only shudders when i step on the gas pedal like 40 percent or more.

It idles perfectly fine, it cruises fine at any speed. I even slowly got up to 4000 rpms just fine without it shuddering. It only happens when I throttle at more than a certain point.

What's the dealio?!?! Thanks

 

Nobody has any ideas?

 

check/change fuel filter, fuel pressure and air cleaner. when changing fuel filter dump the contents of the old filter (from the tank side) into a clear container and see if theres water and/or lots of crudd. try getting it scanned for codes to see if anything is showing there.

 

Thanks. I just changed the fuel filter but didn't check for crudd I'll have to dig it out of the trash can.

And a new update... it seems that the car runs fine when it's not all the way warmed up. After I installed the fuel filter and the car had been sitting for a couple hours... I took it for a spin and it was flawless for about 3 minutes. Then it started to be crappy again

 

i would suspect the fuel pump is failing.

 

When were the plugs & wires last changed?

 

Plugs and wires I'm not sure but I know it wasn't THAT long ago.

And if it was the fuel pump... wouldn't it shudder when i got to high rpms accelerating slow? Like I said... when I accelerate slow, I can get up there without any problems.

 

may or may not, only way to know for sure is to hook up the fuel pressure gage and tape it to the windshield and go for a ride to see if the pressure falls on wot. check the maf to see if damaged or dirty, check air filter, clean or replace if needed and maybe pull a couple plugs to see if theres any indication of fouling. give the local parts store a call and see if they can scan it for you for trouble codes.

 

Ok I'll try some of those thanks.

 

Keep in mind that the fuel injection system is "open loop" for the first few minutes of operation. That means that injector duty cycle is determined by lookup tables programed into the PCM. These have been experimentally determined in a lab using some pretty intense instrumentation and dynos.
Once a cetain time period following startup has passed, however, the PCM begins using info from the Oxygen sensors to determine fuel injector pulsewidth. This is called "closed loop" operation.
In closed loop operation the O2 sensor is the big dog -- if the mixture at the O2 sensors is rich, the injectors deliver less fuel; if the mixture at the O2 sensors is lean, the injectors deliver more fuel.
It sounds to me like your car runs fine when it's in open loop mode but when the oxygen sensor data is relied upon (closed loop) everything falls apart.
So I'd look very carefully at the oxygen sensors. Do you have a scan tool to monitor them?