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Ford Focus Runs Rough At Idle

Q. Hi, I have a 2000 Ford Focus LX, 2.0 liter SPI, not dual-cam, automatic transmission with about 71,500 miles. My problem has me stumped. The car idles rough, whether hot or cold, but it's fine when the gas pedal is depressed. I've changed the spark plugs, plug wires, fuel filter, oxygen sensor, air filter, had the fuel injectors cleaned at the dealership, and poured many bottles of injector cleaner into the tank.

Ford Focus Runs Rough At Idle

That seems to do the trick until I get close to empty, but will continue if I don't pour another bottle in during the next fill up. I use Chevron gas, if that makes a difference. I've been thinking it's my EGR system, so I unplugged the line from the solenoid to my egr valve, and no difference, although I feel a vacuum pulsation coming from the solenoid at idle. I hear that may be bad. Is there anything else I can try before I take the car in and dump a couple hundred dollars on it? I'd like to fix it myself.

Thank you so much for reading my email,

A. I'm thinking you're probably right about it being an EGR problem. The 2000 to 2003 Ford Focus has a problem with water getting into the Differential Pressure Feedback EGR (DPFE) Sensor. The specific fix for this depends on when the car was built.

The one procedure they all have in common is to seal the DPFE Sensor. There are two types of DPFE Sensor mountings. For the ones mounted on the firewall:

Firewall Mounted

  1. Remove the DPFE.
  2. Fold the insulation on the partition wall 900downward so it lays over the top of the EVR.
  3. Reinstall the DPFE such that the insulation is trapped in place between the bottom of the DPFE & the top of the EVR. Tighten to 36 +/- 6 lb-in. (4.1 +/- 0.7 N.m) (Refer to Figure 2).
  4. Verify the DPFE & EVR hoses are fully seated.
Ford Focus Runs Rough At Idle
Figure 2

Tube-mounted DPFE

  1. Remove the EVR solenoid.
  2. Trace out a 2.5" wide x 3" tall rectangle in the insulation, starting from the bottom, and just outside of the EVR mounting lugs.
  3. Cut vertically upward from the bottom along each of the two vertical lines, stopping at the line drawn horizontally.
  4. Fold the section of insulation 900upward.
  5. With the insulation held up, reinstall the EVR solenoid. Tighten to 36 +/- 6 lb-in. (4.1 +/- 0.7 N.m) (Refer to Figure 3).
Ford Focus Runs Rough At Idle
Figure 3

Another possibility common to all 2000 to 2004 Ford, Lincoln and Mercury products is vacuum leaks. So a through check of all the vacuum lines and hoses is a good idea.

Additional Information provided courtesy of AllDATA

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© 2005 Vincent T. Ciulla

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