View source for Cold Start idle reduction

[[Car_MPG_Efficiency_Modifications_Main#Drivetrain_Mods_-_Engine_Mechanical|Back to main mod page]]

[[Image:ColdIdle.JPG|right|thumb|300px|Frame|]]
'''Introduction'''<br>
Cars when started cold can have a high idle level. This means high RPMs and high fuel usage.

The high idle is designed into the cars to warm up the engine quickly and to ensure that the car doesn't stall out while the oil is cold and thick. 

If your car has a high idle when it starts up cold and you want a more efficient car and you don't mind the risk of stalling or increased engine wear this mod is for you.


== Instructions for mod ==
Cars will set the volume of fuel used by attempting to match the amount of air that feeds into the engine so the modification is performed by reducing the air that flows into the engine while the car is cold.
[[Image:IdleControlValve.JPG|right|300px|Frame|]]<br><br>

Depending on the car type there are different ways to perform this mod.

For a car with an older style thermomechanical idle device <br>

- Locate the idle control module (next to the air inlet manifold)<br>







[[Image:IdleControlValveRemoved.JPG|right|300px|Frame|]]<br><br>












- Remove the idle control module (if the idle control module is to be removed completely from the car the radiator may need to be drained and the coolant pipes may need to be removed)<br>





[[Image:IdleControlValveBlocked.JPG|right|300px|Frame|]]<br><br>











- Locate the channel which feeds the thermomechanical idle control device<br>
- Install something (maybe a sheet of metal from a drink can with a few holes so there is a little extra air when idling) to reduce the air flow that can flow through this channel<br>














[[Image:ColdIdleBeforeAfter.JPG|right|thumb|600px|Frame|Fuel usage at cold start before and after mod]]




- Reinstall the idle control module (which may sandwich and hold the flow restricting metal)<br>
- Test the car can start and idle when cold, if the RPM is too low when cold turn off the engine, remove the restricting metal and poke holes in it until the idle level is sufficient.<br>


















== User experiences  ==
Please enter your user name and any relevant data in the table<br>
{| cellspacing="0" Border=1
|+ User data
! User Name !! Car Make, Model, Year !! Cost of Mod !! Time to Perform Mod !! MPG Before Mod !! MPG After Mod !! MPG improvement guess !! Instruction Link
|-
|Saand || Mazda, 626, 1991 || $0 || 1 Hour || 0.369 L Fuel used over 850 seconds from start up || 0.259 L Fuel used over 850 seconds from start up || 0.108 L max saved every cold start|| 
|}

== Problems / Consequences of mod ==
- Engine stalling or a very low idle.
- Low idle while in drive may cause the engine to stall to avoid this double pedaling may be required.

== References ==
=== Forum thread links ===
[http://ecomodder.com/forum/showthread.php/disconnected-idle-air-control-lower-rpm-after-cold-618.html Disconnected Idle Air Control - for lower RPM after a cold start]

=== External links ===