Rough idle

Tiny
TRAVISBIGT59
  • MEMBER
  • 1994 FORD PROBE
  • 4 CYL
  • 2WD
  • MANUAL
  • 170,000 MILES
I drive a 94 ford probe se 2.0L manual tranny and when at an idle the rpms are low and it vibrates more than normal, it seems like it wants to stall, and the acceleration is sluggish at takeoff. I changed fuel filter, pcv valve, spark plugs, and the mass airflow sensor. Its still doing the same thing. Any ideas what could be causing this?
Sunday, April 3rd, 2011 AT 11:41 PM

6 Replies

Tiny
CARADIODOC
  • MECHANIC
  • 34,330 POSTS
Check the fresh air tube between the mass air flow sensor and throttle body for cracks. There must be no air getting into the engine that doesn't go through the sensor.
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Monday, April 4th, 2011 AT 12:13 AM
Tiny
TRAVISBIGT59
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Well I just checked it and there is no cracks. I dont know what else to do.
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Monday, April 4th, 2011 AT 4:00 PM
Tiny
CARADIODOC
  • MECHANIC
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The next step would be to find a mechanic with a scanner that can read live sensor data to see what the Engine Computer is seeing. It will show whether the oxygen sensors are reporting rich or lean conditions vs. Switching rapidly between those like it should. You might also suspect a dirty mass air flow sensor. If it doesn't read the correct amount of incoming air, the computer won't command the proper amount of fuel to go with that air. You'll get the same result from a vacuum leak too.
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Monday, April 4th, 2011 AT 7:08 PM
Tiny
TRAVISBIGT59
  • MEMBER
  • 4 POSTS
I actually put a new mass airflow sensor on it already. I was gonna get my friend to put his scanner on it tomorrow. He told me he thinks its the idle air control valve. I really hope not cuz thats an expensive part.
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Monday, April 4th, 2011 AT 9:48 PM
Tiny
TRAVISBIGT59
  • MEMBER
  • 4 POSTS
Still havnt figured out the problem. I think I may have a catalytic converter problem. The exhaust smells funny and im just noticing this. I also forgot to mention when I get it over 2500 rpms it seems to stop vibrating and pick up power. Any help Plz
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Monday, April 18th, 2011 AT 2:46 AM
Tiny
CARADIODOC
  • MECHANIC
  • 34,330 POSTS
Boy, that sure sounds like a cracked air tube. That is REAL common on Probes. Instead, check for a vacuum leak in one of the smaller hoses. Try pinching them off at various places to see if the engine smooths out.

You can also try introducing a little propane through a vacuum hose. If that clears up the running problem, not enough fuel is getting in.
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Monday, April 18th, 2011 AT 3:52 AM

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