I have an 03 F 150 with the 5.4. Occasionally when going to start it it will crank but not start until I hit the gas. It also has a rough idle. When I hook up my scanner it shows no DTC's.

My first thought would be the IAC, should that throw a code? I tried cleaning it, but according to one of the stickies cleaning doesn't help very often.

So basically what I am asking is will a bad IAC cause a no start?
If I should replace it, is there any brand that is better than the others, or should I stick with motorcraft?

Thanks!

 

Yes, a bad IAC will not throw a code nor will it start unless you pump the gas to it.

 

I bought mine at the Ford dealer, plus a new gasket. Works great.

 

The IAC I put in mine was from Napa Auto Parts. I know it wasn't Motorcraft. Mine didn't throw a code either, just started idling rough. After reading several posts on here, replaced it and it has idled fine ever since.

 

Thanks guys. Sounds like i will be picking up a new one soon. Seems like that should be the most likely cause.

 

BTW, pumping the throttle does not do anything.
It's not a carburator.
Only thing it would do is allow air to enter as the IAC would do.
Holding wide open above 7/8 throttle, as detected by the TPS, will shut the fuel off to the injectors.
This is how you would clean out the cylinders from being flooded from an ignition failure or fouled plugs.

 

When mine went bad, the only way it would start was to give it gas.