SuDZ

When I first start the Max after it has been sitting for a little while I seem to be idling pretty high. Around 1200-1500 Rpms. If I let it run or if I drive it it will drop back down to normal after a few minutes. But at first like I said is almost double what it should be at. Any Idea what would be causing this? I just this weekend did an oil change and the fuel filter will be done this weekend but looking to see what else may control this.

Thanks

SuDZ

Sonic

Check the idle adjustment screw, it sits on the throttle bosy and is black in color. Try turning it and see if it lowers the idle. Otherwise, make sure the Idle Air control hose is still attached onto your intake. It is the small hose that sits right next to the two bigger hoses on the intake resonator.

Sonic

Otherwise, the car will idle that high until the car is warm.

SuDZ

I will check it out. Is it common for this to become undone or altered?

SuDZ

Sonic

No. However, when you start MOST cars up, they idle at ~1300 rpms for about 15 seconds, then slowly spool down until they settle at ~650.

Daniel B. Martin

Any air which "sneaks" into the engine from a source downstream of the Mass Air Flow Sensor is called False Air. False Air will cause RPMs to increase. There are several possible sources of False Air. Because your RPM increase is seemingly random the first place to look is the flexible duct which conveys air from the MAFS to the Throttle Body. The engine moves around a bit on its flexible mounts during normal operation. If there is a crack or split in that air duct, engine movement may cause the crack to open and close. Every time it opens, RPMs go up. Every time it closes, RPMs drop.

Other sources of False Air include a damaged or disconnected vacuum line, a stuck-open Positive Crankcase Ventilation valve, and a leaky power brake vacuum line check valve.

False Air is one of those problems which does not set a Diagnostic Trouble Code and turn on the Malfunction Indicator Lamp.

When the engine reaches normal operating temperature the electronic engine management system goes into Closed Loop mode. The Oxygen Sensors sense the concentration of oxygen in the exhaust stream. The Engine Control Module (the computer) uses the signals it receives from the Oxygen Sensors to adjust the fuel mixture. False air puts extra oxygen in the exhaust gas. The ECM responds by directing the fuel injectors to correct by supplying extra gasoline. More air plus more fuel equals higher RPMs.

We commonly refer to the accelerator as the "gas pedal". With modern fuel injected engines this has become a misnomer. It is more properly called the "air pedal".