[Eighth_mile]

My wifes 2004 se focus with 2.0 zetec recently started sounding like a diesel when under light throttle and idling. I replaced the tensioner thinking that was it, but it still does it. It is SEVERLY worse when air conditioner is on. I am being told AC compressor bearing or compressor itself is bad and trying to fail.

I am leaning towards agreeing because it only has a tiny rattle when ac is off. Also having to deal with a surging idle that makes engine waver almost 3-500 rpms. I thought about mass air meter, but cleaned it and it still does it, although not anywhere near as bad as originally. Should I just burn it to the ground or fix it?

The car still gets good mileage and runs good when going down the highway, although down a bit on power. I still want to clean/replace injectors and put the E3 plugs in it.

Any suggestions would be helpful, but lean on the cheaper side of things first..

 

[iminhell]

Replace the plugs with stock plugs.
The fancy ones don't work correctly.

If cleaning the Mass Air Sensor seemed to improve it, then it sounds like a fueling issue. Could be something from a vacuum leak to a failing fuel pump.

Check for vacuum leaks,
Pull the vacuum line off the Fuel Pressure Regulator to make sure it has not failed,
Replace the fuel filter,
Check the plugs and wires,
Scan the car for codes,

That will at least narrow down the list of possibles.

 

[Eighth_mile]

plug wires are new
plugs will be getting replaced next weekend along with fuel filter. No CE light is on.
if I pull the vacuum line off regulator, what will the car do if its working properly?
I can check for vacuum leaks with starter fluid cant I? spray it around and if engine revs up or bogs some there is the leak in that area?

Thanks for suggestions but wont have an answer until next saturday at the earliest. Oh yeah, its on it 7th alternator.. I am getting plenty of practice with changing it out.

 

[iminhell]

You won't notice any change when removing the FPR line. You'll only want to check for fuel in the line, which is a sure sign it's bad.

I don't like spraying combustible liquids around a running engine. I think making a vacuum tester is a safer method.
Something like a tire valve and a plumbing cap (rubber one) over the throttle body, then pressurize with an air compressor.