Hey guys
I.m new to this forum, and was wondering if anybody can give me some advise on a problem I am having with a 4.6 2003. Problem WAS that the Idle speed was to low, and when it was put in drive or reverse (gear) the engine would kill..the dash had a light, so I took to Auto Zone to have the code read, and it came back with Po443 EVAP and P1507 IAC valve..so I changed the IAC thinking this is the problem. Now when I start it up in park the rpms goes to 2500 and then backs down a few seconds later to 1000 and stays there for a few seconds and then down to 700 800 rpms where it belongs..If I give it gas its acting like the throttle is sticking, but it not.now when i go down the road it stays at 1000 rpm, like the cruise is on, when i come to a stop it coughs slightly and goes down to the normal rpms after 3 seconds. It idles great with no missing, no hesitation whatsoever. I took the IAC back to Auto Zone, and exchanged it for another one, thinking they gave me a bad part, put the newer part on, and the same thing happens. I took the old original part cleaned it with carb cleaner, reinstalled it and its back to the low idle still again, back to the original problem, whats going on here? Is it possible that the computer has to be reset, for it to reconize the new part, or do I have another problem?

 

The computer does have to be reset.

Disconnect the neg. battery cable for about 10 minutes.

Then you have to drive the truck. It may take time for the truck

to re learn driving conditions.

Did you address the P0443 DTC yet?

BTW welcome to FTE!

 

what do i do for the po443 code? I haven't done nothing on that end..

 

Could be a bad gas cap seal or a bad hose in the evap system.