Not sure if this is normal or not, but I wish it didnt do it, when I start my truck, even when its hot, it idles at like 1500 for about 4-5 seconds, then slowly down to idle speed, is this normal or is the IAC valve not doing what it should? My friend has an 02 mustang gt, and when he starts it, even when cold, it almost immediately goes to idle speed. I wish mine did that.

 

built, my stock 98' 4.6 does the same thing and the best explanation that I have got is the valve seals are leaking a little oil into the cylinder and causing it on start up. My 03' 5.4 doesn't do it. Maybe that will help.

 

hmm i dont think thats my problem. I never see smoke.

 

yea, I think its really a PCM error with the injector drive part on startup, again I don't know and have give up trying to figure it out. I didn't say but I do have the smoke at cooler temps.

 

I have no smoke from mine on start up!!!Mine has always done cold since i bought it with 45,000 miles.It never does it if the motor is warm

 

Same here that's how mine has always started - No worries..You just the normal Joe 4 now any ways - That is until you shovel the coals to that new motor on stand-by... Wahooo!!!

 

haha yea lol ill have some irregular idling but i think it will be normal!

 

A cold start or restart depends on the following provided there are no faults;
The coolant temp, the air temp.
The start opens the IAC to admit more air. This raises the speed.
If cold engine, a software timer is running in the back ground as well as how fast the OX sensors heat up to temp and able to control the fuel injection and slowly close the IAC down to match the software program value.
If the start speed goes hi even on a hot restart when not really needed, there is most likely a problem somewhere but it won't hurt anything otherwise..