Vehicle has a rough idle in all gears

Tiny
JILLIAN TAOY
  • MEMBER
  • 2001 FORD ESCAPE
  • 3.0L
  • V6
  • 2WD
  • AUTOMATIC
  • 180,000 MILES
I changed the intake manifold, upper and lower intake manifold gaskets, new IAC and sensor, new MAF sensor, new PCV hose, new OEM spark plugs, coils packs tested okay. All new oxygen sensors, new EGR gasket, fuel injectors tested okay. Cleaned the throttle body and still a rough idle. I can hear a hissing toward the back of the engine (near the firewall), sprayed it to listen for a change in the engine and nothing. Catalytic converter tested good. Cleaned and tighten the pipe connected to the EGR valve. Even replaced the brake booster! There are no oil leaks showing under the car. The rough idle started after changing the intake manifold. The intake manifold is an OEM part direct from Ford. What could it be?
Wednesday, October 9th, 2019 AT 12:41 AM

5 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,055 POSTS
Welcome to 2CarPros.

First, check to make sure the three vacuum hoses on the rear of the engine are not broken, cracked, and they are securely connected. Also, check the PCV valve to make sure it is fully in place and the hose to it isn't cracked or leaking.

Pic 1 shows the three vacuum hoses I'm referring to. Also, check the vapor management vacuum supply (pic 2).

Let me know what you find. Also, if you have a live data scanner, check the fuel trims to see if it is running lean which would indicate a vacuum issue.

Take care,
Joe
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Thursday, October 10th, 2019 AT 7:44 PM
Tiny
JILLIAN TAOY
  • MEMBER
  • 5 POSTS
The three vacuum hoses in the back where replaced and the PCV valve was replaced and secured. We check these areas several times to confirm. Also did a smoke test and no vacuum leaks could be located. I’m stumped
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Friday, October 11th, 2019 AT 3:49 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,055 POSTS
Welcome back:

Do you have a live data scanner? If you do, can you tell me the short term fuel trims at idle? Also, could the hissing be coming from an exhaust manifold leak?

Let me know.

Joe
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Friday, October 11th, 2019 AT 8:50 PM
Tiny
JILLIAN TAOY
  • MEMBER
  • 5 POSTS
Here are my fuel trims:
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Monday, October 14th, 2019 AT 9:58 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,055 POSTS
Welcome back:

You have a vacuum leak at some point. Bank 1 STFT are extremely high. Basically, the computer is trying to compensate for a lean fuel mixture by adding fuel to that bank. Are there any exhaust leaks? Something has to be letting unmetered air into the system before the catalytic converter.

Let me know.

Joe
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Tuesday, October 15th, 2019 AT 5:09 PM

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