IAC question

fordmuscle395

Member

Jul 9, 2008

114

0

16

Sumter, sc

Oct 29, 2008

#1

• Oct 29, 2008

• #1

I was just wondering...
When i start my car I usually have to crank it twice to get it to run and is usually followed by rough idle until you drive it for a little . One of the things I'm looking at is the IAC. So I disconnected the IAC while it was running...should it act different? Also, I know on most cars when you turn on the A/C, the idle changes to compensate, does the idle change on these cars?

 

J

Jack's95gt

Member

Aug 15, 2004

443

1

18

Huntingdon Valley, PA

Oct 29, 2008

#2

• Oct 29, 2008

• #2

Another thing to look at is the fuel pressure. Rent a gauge (Autozone) if you don't have one and watch it through the startup and idle, and shut down. You should be around 35- 40 psi and it should hold that after shut down.

 

HISSIN50

"How long does it take to get help in here?

15 Year Member

Nov 29, 1999

31,179

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129

Oct 30, 2008

#3

• Oct 30, 2008

• #3

On the same fuel note, you can try cycling the key a few times before ever cranking the engine over (to build fuel pressure). If you do this and then it starts immediately, that suggests a pressure issue.

The IAC will compensate your cold idle, and loaded idle (like when the AC is on, as you noted). The hot (non-loaded) idle might not be affected, depending upon how your mechanical idle is set.

Good luck.

 

fordmuscle395

Member

Jul 9, 2008

114

0

16

Sumter, sc

Oct 30, 2008

#4

• Oct 30, 2008

• #4

I cycled the key a couple a times, like you said. Turned the key over...started up, but immediatly started losing idle speed, luggin' and crap, till its just on the verge of dying then picks itself up (w/o me touching the throttle) and idles fine. what do ya think?

The check engine light has never come on. Im gonna hook a scanner up to it to see if its throwing any codes, also Ill probably try that fuel pressure tester.

 

HISSIN50

"How long does it take to get help in here?

15 Year Member

Nov 29, 1999

31,179

33

129

Oct 30, 2008

#5

• Oct 30, 2008

• #5

Codes and FP testing definitely are next steps. It can still be an IAC issue but because it's tough to test an IAC on your own (it has a square wave output), you kind of replace one after deductive observations.

Good luck.