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Check engine codes

Tiny
COREY H JENKINS
  • MEMBER
  • 1996 CHEVROLET TAHOE
  • 5.7L
  • V8
  • 4WD
  • AUTOMATIC
  • 253,000 MILES
Check engine light came on. Had it tested at local auto parts store. Came up po507
What is this and how do I correct it?
Sunday, June 11th, 2017 AT 4:14 PM

11 Replies

Tiny
CJ MEDEVAC
  • MECHANIC
  • 11,005 POSTS
If the code is not just crying "wolf", the normal/usual symptom is your idle speed being higher than normal.

Things you can look for/do:

Look for vacuum leaks anywhere/ same thing from behind the throttle body to the engine/ around the EGR.

Could just need a PCV valve.

If it is dirty, clean the throttle body (both sides of the throttle plate) with throttle body cleaner.

Look for and repair any emission lines/ hoses.

Your IAC (idle air control) may be on the "downhill".

If you are seemingly not having a problem, reset the code and see if it returns.

I hope this has helped you.

The Medic
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Sunday, June 11th, 2017 AT 9:03 PM
Tiny
COREY H JENKINS
  • MEMBER
  • 80 POSTS
What does IAC on the downhill mean?
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Monday, June 12th, 2017 AT 2:08 AM
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
Idle air control motor which is mounted on throttle body. It controls the idle of car and is normally a small oblong hole on throttle body you can see it when duct work is off of throttle body.
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Monday, June 12th, 2017 AT 5:20 AM
Tiny
COREY H JENKINS
  • MEMBER
  • 80 POSTS
I know about the idle air motor, I was asking about the downhill meaning.
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Monday, June 12th, 2017 AT 5:52 AM
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
It controls the idle on the motor by opening or closing shutting off or letting more air in by how computer tells it what to do. See picture for description of operation I assume that is what you are meaning by "downhill".
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Monday, June 12th, 2017 AT 6:27 AM
Tiny
COREY H JENKINS
  • MEMBER
  • 80 POSTS
CJ medevac used that phrase.
Not sure the meaning.
Can the idle air control valve be put in backwards(180 turn)?
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Monday, June 12th, 2017 AT 6:58 AM
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
Not that I know of.
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Monday, June 12th, 2017 AT 8:00 AM
Tiny
RENEE L
  • ADMIN
  • 1,260 POSTS
Hi COREY,

The phrase CJ MEDEVAC called "on the downhill" means it is going bad.

Sorry for the confusion.

Renee
Admin
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Monday, June 12th, 2017 AT 11:56 AM
Tiny
CJ MEDEVAC
  • MECHANIC
  • 11,005 POSTS
Just got in.

I approve that message!

Sorry, South Carolina lingo.

The Medic
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Monday, June 12th, 2017 AT 4:19 PM
Tiny
COREY H JENKINS
  • MEMBER
  • 80 POSTS
It has a new idle air control valve.
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Monday, June 12th, 2017 AT 4:29 PM
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
Couple off things to try first clean IAC hole as well as throttle plate on both sides with choke cleaner then check fuel pressure with a gauge like it may have a bad or going bad regulator. Also, these earlier units had a lot of poppet valve trouble and they needed replaced because of this. You should have 60-66 psi with key on only it should hold at 55-60 psi.
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Monday, June 12th, 2017 AT 6:13 PM

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