• The site migration is complete! Hopefully everything transferred properly from the multiple decades old software we were using before. If you notice any issues please let me know, thanks! Also, I'm still working on things like chatbox, etc so hopefully those will be working in the next week or two.

Cold Air = Lean?

SlowNA06

New member
Went down from PA to NC for Thanksgiving. Took the gtp. It runs pretty rich. Averaged like 25mpg on the way down. Here's the results on the drive back, when it was much colder. Reset everything with gas fill.

5256490891_375f7b8549_b.jpg

5256490897_078a707fe4_b.jpg
5256490903_150c635a5a_b.jpg
 


yes, cold air means the car will run leaner. colder air is more dense, therefore youll be getting more air per fuel charge. that is why normally you should retune a car that is running on the ragged edge of blowing up for winter because otherwise you will blow it up.
 
yes and no.

the o2 sensor does its job to up fueling when it notices that the AFR is high.

however, the colder air in this case is increasing timing VIA the IAT sensor which is increasing the possible MPG the car is able to achieve. however, most will see a decrease in mileage in winter for a few different reasons (winter blend gas, longer warm up cycles, more idling time, etc).
 
Please step on my toes if you don't agree but one thing that factors in often the sensors don't handle well is humidity variations. Over all an engine will produce less power with higher water content in the fuel/air mixture, regardless of temperature, the *effect* still occurs. As the PCM fights to make adjustments to compensate for many changes in altitude and air intake for mixture, listening to knock sensors for timing adjustments, water content and changing especially while traveling distances just throws a curveball to the whole process.
 
I agree, but I think that in the end that this is all academic.

You can't control humidity, water content of the gas, ambient temperature etc. What you can control is your driving habits and the mechanical operation of your engine (i.e. make sure it's operating correctly etc).

Both trivialize the remainder of the variables in the equation of fuel mileage.

Another thing: the DIC mileage on my GTP is a joke (fwiw). It's lucky to be within 20% for real accuracy.
 


Back
Top