I have an 05 Impala with 3.4L engine. From start-up the engine idles as if someone has foot fully applied to the gas. I took the car on the road; it accelerates to around 50 mph without applying the gas. I took it to AutoZone for free diagnostics. They pulled multiple codes: P0101, P0102, P0107, P0108, P0122, P0300 and P0405. Please help.
Many of the major electronic control circuits have apparently gone completely wacky:
P0101 & P0102 relate to the Mass Airflow Sensor (MAF)
P0107 & P0108 relate to the Manifold Absolute Pressure sensor (MAP)
P0122 relates to the throttle position sensor (TPS)
P0300 is a random/multiple cylinder misfire
…and P0405 is EGR related.
Adding all of that up, I don’t think that anyone will be able to help much from afar - you need someone really good with diagnostics - hopefully one of these things is awry and setting off dominoes (like maybe the TPS). But be prepared in the event that you need a new ECU (computer) for this car.
This is one of the signs that the engine management computer is defective. There’s no chance that all these engine management systems have failed all at once. However, the computer in your vehicle is warranted for 8 years/80,000 miles. So if you fall under this criteria, the dealer must install a new computer at no cost to you.
before the high idle started i had changed the plenum gasket, is it possable a part of the old gasket is stuck on a valve and make all the trouble