Start the engine, and spray a little carb cleaner around and on the EGR valve. If the engine changes sound are idles up are down then the valve is bad.
You can tell a bad valve by doing a compression test.
If your car has one, take the vacuum line to the modulator off and if there is fluid inside, the modulator is bad.
You can tell when a manifold tuning valve is bad when oil is leaking through it. You also can tell by inserting the dipstick into the valve and seeing if oil comes out through the dipstick.
Diagnostics
No, some rattle is normal.
Bad bearing Bad valve
Is your clutch bad or wearing out ?
valve seals and or guides bad
if you get to get gas the car has hard time to start
You could have a bad exhaust valve
I have read that a bad PCV Valve will contribute to gunking up your Throttle Body, which could lead to irregular acceleration issues. I am certain that there is more to a bad PCV Valve than that, as this is an Emission Control item, but hopefully someone who knows more will chime in. SUBMITTED: Friday, 03JUN11
You know the starter is going bad when you have a dragging starter.