I have some driveability issues and wanted to know what symptoms a bad/ failing idle air control valve would have- First- upon first cranking and until the engine reaches normal operating temperature the idle is around 2500-3000 rpm Then when at idle afterwards the idle oscillates from about 800-1300 rpm When taking off from standing the car has symptoms like it is starved for fuel - shudder, lack of power, etc. - if you let off the throttle then apply more gently all the power is back and drives normally. Things that have been checked: fuel pressure- both at idle and at throttle- checked while driving- is within specs (I forget the exact PSI) when acting up the fuel pressure INCREASES slightly, like the injectors are not opening? EGR valve and EGR control have been checked and ruled out. The EGR I know can cause similar symptoms but doesn't seem to be the culprit. All vacuum/intake hoses/etc have been checked for vacuum leaks- all small lines were replaced. The MAF is working and the ground was checked to make sure it was getting grounded properly
At highway cruising speeds (50-70mph) the car is smooth with good power and acceleration. At lower speeds when you press quickly on the throttle you will get bucking and hesitation like you are in the wrong gear or are running out of fuel. Also when running the AC all symptoms are magnified somewhat- especially starting from standing- the car will almost die...
I had an injector go out completely and I replaced it but can injectors fail intermittently? that would explain my problem but it doesn't seem really likely? Thanks for any advice on what to check!
-rw