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2000 Mercury Cougar Base 3dr Coupe I4

2000 Mercury Cougar
Trim Info:
Front Wheel Drive, 3 Door Coupe, Compact
24 mpg city / 34 mpg hwy
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March 3, 2013, 12:01 pm

Stephanie C

Question: What is causing my car to shake?

A previous owner did not instal the engin properly and fluids were being fried on the cylinders. I installed a new engine, from an 02' cougar with 50k less miles, and it seamed to work fine. After a few months the car sounded like it was misfiring or the belt was slipping but when I looked under the hood I could not find any evidence to support that. It would also shake back and fourth violently while idle, accelerating, and at any constant speed. Since this first started it has gotten much worse and more constant. I know there are a few other things that have to be fixed but I don't foresee those having anything to do with the noise and the shaking.

March 3, 2013, 1:14 pm

Ron W
Expert Mechanic

Sounds like a severe misfire. Is the check engine light on? If it is, the codes stored will help find the source of the misfire. Could be a crank position or ignition module problem, or a fuel related issue. Sounds more like ignition.

You should also check with a part store to make sure those engines are compatible. Sometimes a model year different engine will not work due to the way the crank senors read (even if it fits physically in the car)

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March 3, 2013, 2:15 pm

Stephanie C

The engine light was on with the previous engine but not since the new engine was installed.
Yes the majority of parts from and 02' are compatible with an 01', myself and three mechanics have checked.

Someone else suggested that it had something to do with the transmission but would that have anything to do with the shaking or the sound or would it just be an additional problem? All fluids come back fine and have always been checked and replaced properly.
If it is more of an ignition module problem, do you have a suggested quote on what it would be to fix that?

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March 3, 2013, 3:14 pm

Ron W
Expert Mechanic

If there is an imbalance in the transmission (like loose torque converter bolts or a cracked flex plate), that could definitely cause this type of issue.

I just looked at a picture of a 2.5L engine for a 2001 Cougar. Says it fits 2002 as well, so you are probably right that it is a correct install. One thing I noticed, the coil pack (with the ignition module) still has spark plug wires. You might want to start with changing the plugs and wires as a simple tune up may resolve the issue. If not, the coil pack is under $50 and is another possible cause.

Lastly, if you have a mechanic friend, have them make sure the wires aren't crossed and isolate which cylinder (s) are the issue. That will help sort out if it is engine or transmission related.

From your description, it sounds very much like an ignition system issue.

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