2000 Mercury Cougar idle

JAMES79NEFF

MEMBER
2000 MERCURY COUGAR
6 CYL
2WD
AUTOMATIC
100,000 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

3 Replies

GREYHEN

MEMBER
4 POSTS

Does the check engine light come on?

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Tuesday, March 3rd, 2009 AT 5:41 PM

F4I_GUY

MECHANIC
3,302 POSTS

It sounds like an Idle Air Control Valve (IACV) issue. I would try servicing it first and see what happens.

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Tuesday, March 3rd, 2009 AT 5:55 PM

GREYHEN

MEMBER
4 POSTS

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

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Friday, March 6th, 2009 AT 1:22 PM