All of a sudden power loss

Tiny
MRSLEGER
  • MEMBER
  • 2002 MERCURY COUGAR
  • 91,000 MILES
I just got this car and it was performing well when rpms 3000 and over. At lower rpms it was cutting out and only if I was on the gas to shift down or manually shift the transmission or overdrive off switch would it not cut and hesitate. So I was looking at the plug wires and noticed they had never been changed. So I got new spark plugs and wires. As I changed the plugs one was very different than the other 5. It smelled of fuel and was wet. Next was test drive and no more low rpm cutting out. So that was a victory for me. Until I was on the freeway and got on the gas and no power at all. As long as I stay light on the peddle it will operate normal but 2800-rpm and up it performs terrible as I'm on the gas and I'm looking at my tach. 3000 rps is when it starts to sound like its got a k&n air filter or no air filter. Lots of sound but being made. But power is lost. What did I do? I would rather have it cutting out like b4 I made my repairs. It was better than now. At least if I kept the rpms up it would haul and was fun to drive. Now I dont even want to pass slower cars in front of me please help.
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Thursday, April 18th, 2013 AT 5:43 AM

5 Replies

Tiny
WRENCHTECH
  • MECHANIC
  • 20,758 POSTS
If you keep driving it ion that condition, your problem are going to really multiply.

The first thing you need to do is have the stored trouble codes read and then I would take a complete compression test.
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Thursday, April 18th, 2013 AT 6:00 AM
Tiny
WRENCHTECH
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I know you're asking for more help but until you can start giving me some info, I have no way to conclude anything.

What was the compression reading in that cylinder?
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Thursday, April 18th, 2013 AT 11:43 AM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
From your description, I dont think the engine is breathing properly. What I mean is that the cat converter may be clogged causing all these issues.

A back pressure test will tell if they are clogged. Simple test doen by a shop where they remove a o2 sensor and insert a gauge and measure the pressure.

A fuel pressure test should also be done to see if the fuel pump is working correctly as well.

Start there

Roy
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Thursday, April 18th, 2013 AT 3:19 PM
Tiny
WRENCHTECH
  • MECHANIC
  • 20,758 POSTS
Let's not forget that we have what appears to be a bad cylinder that is fouling plugs.
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Thursday, April 18th, 2013 AT 4:51 PM
Tiny
MRSLEGER
  • MEMBER
  • 21 POSTS
Does the gas tank have to come out to change fuel pump?And what is the procedure to do this?
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Sunday, May 5th, 2013 AT 2:01 PM

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