Engine starts and idles high

Tiny
SCHRIMPIEMAN
  • MECHANIC
  • 166 POSTS
Your issue is likely the Idle Air Control Valve (IACV). It rests on top of the throttle body and is easy to replace - - just has two 8mm bolts, a gasket, and a small wire clip. If you remove the IACV, look inside. If it is black with soot, likely it needs replacement.

Since your check engine light did illuminate, it wouild be wise to get the exact codes. There may be other things hidden. Remember the car computer is not a tell-all, and just because the code says there is a fault, it doesn't mean that replacing the part which the computer says is malfunctioning is the cure.

But in most cases with the IACV, just replacing it is the cure.

Other reason for a high idle is a really bad vacuum leak. Check the PCV grommet connection and brake booster hose. Remove hose from brake booster and plug it with your thumb to test it.
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Wednesday, May 5th, 2021 AT 10:38 AM (Merged)
Tiny
WAZNEY
  • MEMBER
  • 1 POST
  • FORD TAURUS
I have a 1999 ford taurus, 3.0L with 136000 miles. After diving the vehicle for about 10 minutes, once in park the idle rises to about 2600 rpm. Sometimes it feels like it does it while it is in drive other times not. This morning it did not rise until about 6-7 seconds after it was put in park. No codes.

Leaky intake? Faulty ics? The air has to be there to allow the rpm to happen. But no codes. HELP!
Rww
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Wednesday, May 5th, 2021 AT 10:39 AM (Merged)
Tiny
BLMO
  • MEMBER
  • 72 POSTS
The idle air control valve could be bad. You can check it by removing it and looking at the bottom. You will see 2 chambers, and a conical "plunger". Actually, it's not a valve, but a motor that screws the cone in and out to control the air flow during idle. It may be stuck, which may explain the intermittent high idle.

Another possible culprit is the Mas Airflow Sensor. It converts airflow to an electrical signal and feeds it to the computer. If it is faulty, it could trick the computer into thinking that the airflow is too high, which will cause the computer to run rich. Tap on the MAF sensor with the handle of a screwdriver while the engine is running, and see if something happens.

However, both of these usually set a code.
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Wednesday, May 5th, 2021 AT 10:39 AM (Merged)

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