The search function is broken so Iturn to you guys for some answers. I have heard it metioned on this site serveral times and I am wondering what it means. What is engine heat soaking? Some people have said when this happens they reset their ECU and everything is back to normal. The reason I'm asking is that my car seems a little sluggish since this heat wave across the South, and I was wondering if this could be it

 

Heat soak is when your in traffic on a hot day and you come to a stop. Hot air from the radiator and heat from the engine cause the air inside the airbox to be hot. When you try to go from a stop the intake sucks in a bunch of hot air and the car bogs when it takes off.

 

Heat Soak is where the air intake (Intercooler, Radiator, etc...) sucks up more hot air from parts of your that emit a lot heat such as the exhaust manifold or from the outside. The hotter the air the less dense it is and which in turn makes less power.

 

So this is just a momentary thing once you are moving again in traffic then it will get better?

 

It'll take a short period before everything cools back down after gaining some speed and allowing air to circulate, but not too long. In short, yes, it's a momentary thing.

P.S.
The search feature is back online and working fine

 

Generally true! I just got home of a round trip to California. Crossing west Texas, New Mexico, Utah, and Nevada, I ran many mile in temps between 100 and 108. The car performed Ok while on the road but I could definitely feel a drop in max performance while passing and such. Also, while dealing with traffic lights and such while driving through the local towns, it wasn't as crisp starting off from a full stop.

The heat soak you're asking about usually comes on when you're stuck in traffic, as others have commented on but the engine will also be effected if you're simply driving on a really hot day as I was on several days during my trip. Hotter air is less dense and all engines will loose power as the temperatures go up. It's an unfortunate fact of life.

Drive Safe,
Steve R.

 

In addition to just loss of power from a less dense air charge, I believe the ECM retards timing when intake air temps get high to prevent pre-ignition. This will be most noticeable during off-idle acceleration, when the ECM typically cranks in something like 40 degrees of timing advance.

With the temps over 100

 

i hate hot air.

 

Buy a good cold air intake;be careful of hydrolock on the cheap ones!