Runs rich and cuts out at low rpm

Harvey N Tawatao

• 3854 Answers
• Posted on May 08, 2009

SOURCE: idle is too low, car dies, engine runs fine

An IAC (idle air control) motor is designed to adjust the engine idle RPM speed by opening and closing an air bypass passage inside the throttle body. The car computer or ECM (electronic control module) receives information from various sensors and will output signals to adjust the IAC motor in or out to adjust engine idle speed by controlling engine idle air.
An IAC motor is highly susceptible to carbon and coking build up; if an IAC goes too long without cleaning it can cause stalling and poor idle quality. Some cars are designed with a large vacuum transfer hose that connects the intake manifold to the IAC (idle air control) motor. If a broken or dilapidated these vacuum lines can cause the engine to lose vacuum which will allow the engine to run rough and die. 
Inspect all engine and accessory vacuum lines to look for missing, torn or dilapidated lines and replace as needed. To check the IAC motor remove the unit, with the wires connected turn the key to the "on" position without starting the engine, the IAC should move in or out. 
If the IAC motor does nothing it has probably failed, replace it with a new unit and recheck system. Note: while the IAC motor is removed clean (use aerosol carburetor cleaner) the passages the IAC uses to control idle air speed.

Good luck and hope this helps

SOURCE: Cobalt not running at low rpm.......

All are possibilities but EGR valve makes the most sense. It's famous for causing poor idling and/or stalling at low RPMS. Best of luck.
Greg

SOURCE: rough loud engine sound when van idles

sounds like your lifters

SOURCE: what transmision is in a 1990 dodge ram van b250

You will have to refer to the id on the pan or on a tag on the transmission. There is the 727,904,and the 999.

SOURCE: 1989 Dodge Truck B250 Van V8-318 ignition control

its built into the ecm located right in the middle of he firewall from under the hood, big black box with two plugs.