Originally Posted by malcolm_x

Be peaceful, be courteous, obey the law, respect everyone; but if someone puts his hand on you, send him to the cemetery.

Originally Posted by sxoc

Thats the temperature correction used for petrol station fuel pumps, so you can be fairly confident its correct

Your ECU should have a compensation based on ambient temp, coolant temp, speed/load (i.e. gas velocity which affects heat transfer) and soaktime for hot start compensation. This is all designed to create a modelled fuel temperature as it passes through the injector. However, it probably won't compensate for an increase in bulk fuel temperature caused by prolonged idling, which is where your fuel cooler comes in.

Having said that, you'd be (un)lucky to raise your bulk fuel (i.e. fuel in the tank) temp much more than 20-30 degrees above the ambient. You can see from the correction data that is about a 3% enleanment, which probably isn't enough to worry about assuming your car is running / mapped correctly. Of course if its too lean to start with then its a problem

Of course if you have a car with a lambda sensor then it corrects itself in the areas where it runs closed loop, and may apply the correction in the open loop region too. if its running fully closed loop with a wide band sensoe then you have no worries at all.

Overall, unless you do a lot of idling then don't bother, as its not worth the effort and wont gain you anything. The cars that I know of that have them fitted are things like Bentleys which tend to waft about on very light loads with a lot of fuel being heated by the engine and then returning to the tank. A better way to avoid the problem is to run a variable or 2 stage fuel pump arrangement, that only supplies just above the required fuel, or a returnless system (most common on modern cars) that doesn't return anything to the tank so bulk fuel = ambient temp.