Is there a reason for having a IAC and a Cruise Control system on a vehicle? Essentially they work the same, but the cruise control is more accurate and has a longer stroke, making it more capable. I'm just wondering why don't they intigrate idle air control into cruise control.

 

my guess is they don't want to link the two systems because cruise control is an option maybe in some countries. also, im pretty sure that iac is only active at idle and doesn't need to be monitored or controlled any other time.

 

^What he said. It's an IDLE Air Control. It is only functional at idle to ensure the proper amount of air gets in depending on whether the engine is cold or at operating temperature. When you are using cruise you are not idling.

 

Rallyman--Dont nock him for the question. It would be pretty easy to set up a system that incorporated the two into one unit (hypothetically speaking).
DTN...
Business wise it just doesn't make since to make something more complicated and less reliable for more money. Relatively speaking the cruise control is a very basic component in a car--doing away with bypass valve and relying solely on the throttle plate would probably cause some idle issues. The way the plate is controlled would probably have to be redesigned.

 

^^ But, it could potentially bring costs down. Not having to manage extra systems, parts stockage, labor. Are you saying the cruise control is less reliable then the IAC? Personally, i use my cruise control alot and have not had any problems, but i have had issues with my IAC. The cruise is able to retain speed in my car +/- 1MPH at any RPM in any gear. It would make sence that it would be able to regulate the RPMs fairly precicely in a similar manner with a bit of tweaking.

But, if you say it is unreliable in comparison to IAC, that would be an answer I'm looking for. It makes sence because of the phase shifting capabilities of the IAC that it could be more accurate.

 

You meant iac right? Not iat--intake air temp.

Accuracy is the issue for one. The iac makes constant changes at idle to compensate for temp/altitude/etc. It's very accurate/precise. All your cruise does is tighten and losen a cable--thats pretty much it. Keep your cruise control on going up and down hills and tell me it doesn't fluxuate. It's been thought of before its just not easily intigrateable and cost effective. Yes, the cruise control is very reliable--it's very basic and it works great that way (thats why it hasn't changed).

 

^^ yeah, IAC. corrected.