shybx1969

A buddy of mine said the K and N filter he installed in his 08 silverado is getting less milage in winter (cold air) than summer, so he runs the (stock) air filter more restrictive in winter for better milage..Is he dreaming or is this based in fact. :roll:

Swiley383

It has been really cold here this winter and I noticed the same thing on my 01 it has a stock air filter. Not sure why could be the high mileage on mine I have no proof that is wheather related yet. We will see this summer.

TheYellaBrick

Icing up in the venturie areas reduces airflow...tire pressures also decrease (more rolling resistance), lubes in the gear boxes are stiffer....

shybx1969

This is true....i think itsa combo of things, i think if anything a less restrictive filter likka k an n would give u better milage no matter what the temp out :roll: ...but im no expert.

coloradoracerguy

Colder air is more dense. Denser air means more fuel is required to maintain the same a/f ratios. My truck is the same way. The computer is just compensating for what it sees as an increase in airflow....something else to consider as well, do you start and warm your vehicle before you drive it? If so, cold enrichment and warmup burn more fuel as well, causing your average mileage to go down......

shybx1969

Ok but in summer then do you get better milage w/a less restrictive filter when its warmer...

gearhead1011

I think he's mistaken. A vehicle with electronic fuel injection will adjust the fuel according to how much air is entering the engine so it makes no difference with fuel economy if the filter is more or less restrictive but a clogged air filter will limit performance. On the older carbureted engines the air filter being restricted would kill fuel economy because fuel was metered with a venturi effect and the restricted air filter would cause the carburetor to pull more fuel into the mix, sort of like having the choke on all the time. A common problem with a K&N filter on a vehicle with a MAF sensor for EFI is the oil from the element can coat the sensor wire and cause a problem with fuel control. When that happens it turns on the check engine light and sets a fuel control trouble code.

That being said the cold weather hurts fuel economy for a number of reasons but I think the biggest part of that is the fact that it takes much longer for an engine to reach operating temperature and go into closed loop. A cold engine needs a richer fuel mixture to run properly and a fuel injected engine uses engine temperature as one of the main inputs for fuel control. The gas you get at the pump is a different blend for cold or warm weather and the gas you get makes a significant difference in fuel economy.

TheRabbit

Not to mention he probably lets it warm up a lot longer before he starts driving. I know when it's cold my truck idles about 20 minutes every morning before I leave.

I'd tell him it's also the colder air that the truck is having to push through. Once the global warming is in full effect it'll get a lot better! lol

roadkill2

X 2 . . . That 20 minute idle or warmup is a mileage killer. My guess (?) on the air filter change is, he's wasting his time, but if it makes him feel good, fine with me . .

If he's that worried about mileage that bad, he needs to trade that Chevy off for a new VW Diesel . .

Swiley383

The mileage dose not make much difference me it could also just be wear on my truck it got 240,000 on it. I agree with Rabbit bring on the global warming I have had enough winter. The post just got me wondering since I have been blaming mine on high mileage.