Engine Performance problem
2000 Mercury Cougar 6 cyl Two Wheel Drive Automatic 100000 miles
when I start the car the rpm jump to 2000 then fall to about 900 rpm the n engine starts shaking while idle jumps then dies restart car happens agin. Unplug maf sensor engine smoothes out. Replace maf sensor w/new one same problem. Unplug egr valve vacum smoothes out. What could this be
It sounds like an Idle Air Control Valve (IACV) issue. I would try servicing it first and see what happens.
March, 6, 2009 AT 1:22 PM
The Exact same thing was happening to my car.
The problem with this type of issue is that there is a lot of intereaction between the functions of alot of the sensors. In effect a failure of one item can look like it is caused by another, I disconnected my EGR valve and plugged the line at the hose. I also tapped on the valve to try and get it to return to the relaxed position. The car ran fine until I plugged the EGR valve back in. Replaced Valve and car has ran fine for 2 weeks (knock on wood). The CHECK ENGINE LIGHT would not come on right away. I got two codes P0171 and P0174. Which are LEAN BANK 1 and LEAN BANK 2