so lately ice been getting even worse gas mileage, i used to get around 250 miles a tank, and that was when i filled up at 17 gallons, now ive been getting 220 tops or sometimes lower than that. recently i had the upper and lower intake manifold gaskets replaced, after that my MAP, and MAF sensor started acting up, so i got them both replaced. its the only car me and my gf have right now so i had to get them at auto zone ASAP. they weren't ac delco replacements. Also, i got the fuel pressure regulator replaced again with an aftermarket brand. I only get gas from sunoco. The weather has been around 30 degrees here in Philly and i have a semi cold air intake. the cone doesn't go all the way in the fender its like half way in and it dosent have a shield for the engine heat, i don't know if that is a factor or not. but guys if yall know of any ideas that might help get my mileage back up it would be much appreciated

 

If,
You still have the stock air cleaner box... try putting it back in. and see if that helps... If not..Get an AC Delco MAF asap... 1 or both should greatly improve your fuel mileage. as the weather gets colder all vehicles will use more fuel. that's just natural.. also driving in the snow knocks down the fuel mileage and other various weather conditions always contribute to changing fuel economy.
A tuneup could also improve your fuel mileage ..
Plugs, wires, oil & filter change, fuel filter, air filter etc...

 

David mentioned what I was thinking, weather can play a part in this. With the cold weather, takes longer for the car to get to operating temp, this can play into MGP. Also, many people tend to start the car and let it warm up before going out somewhere OR while uncovering the snow. Even though it is good to warm a cold car before taking off, keep in mind, that time idling IS timing using gas.

Also, if you are like many others out there right now, you are doing a lot of holiday shopping OR stuck in additional traffic because of holiday shopping. Added stop-n-go/city driving is bad for MPG in general. But if your driving patterns have not changed at all due to the holiday shopping (be it you shopping or the added traffic of others shopping), disregard this item.

And lastly, some/most/all gasoline suppliers put extra additives in this time of year to ward off "fuel line freeze up". I believe the common additive is ethanol. The down side to ethanol, the move of it in your fuel, the lower your MPG (ethanol burns clean, but does not get the same MPG as gasoline).

So, just by the season we're in, you have a bunch of factors playing against you. I honestly don't have a way to tell you if all this should add up to 30 less miles per tank, I'll admit, it seems a bit on the high side.

Given the the time of year and NO ONE likes messing with a car in the winter, keep watch and just ensure it stays pretty consistent, ride out the winter, see if it improves in spring. If it's bugging you, then you can try some basic maintenance. I'm thinking MAF cleaner and change plugs/wires/upstream O2 and see if those steps make a difference.

 

oil change time lol i get to 3k mi and i get 200 mi out of 40 bucks of gas. new oil i get closer to 220

 

i did the whole tune up when i did the car, i even did the upstream o2 just dont remember what brand i used, i will spray the maf to see if that helps and make sure all tires have 40 psi, oil i just did not that long ago right before it started to get cold. and lastly i deff got rid of the stock airbox, what could that clunky box do anyway haha

 

Cold air intake improves performance, (During the summer)

Warm stock air box helps fuel mileage...
Collects and holds underhood temps. Thus using warmer air and less fuel consumption. (During the winter!) IMO

Great advise/info Jason!

 

I thought colder air = More MPG due to the engine heat not being as hot as opposed to the summer time? Hence the reason we use CAIS for the summer, esp when its insulated. I use a simple filter for my 2007, may need a bigger one by now, but my MPG seems to have improved with the 5.3. Maybe its due to the different engine? But my engine stays amazing toasty, and sometime even in the summer time, I think she gets way too hot. But winter time, shes nice and cool, I can totally tell the difference.

 

Colder Air=Better Performance/HP, not necessarily better MPG. But again, this time of year, it takes longer for the car to get to operating temp, which is part of the car running at peak performance for it's tune (as they are tuned to run at operating temp as that is what you are running at more often then not).

On the GM v6 since about '96+ almost all (if not all) flow coolant through part of the throttle body. As I understand, this is an MPG related reason, the slightly warm incoming air (especially during the winter) to help improve MPG. Many think it's to prevent throttle plate freeze up, I personally don't buy into that (unless you are taking the vehicle to Antarctica, then maybe). I say that because the '94-'95 3100 did not have coolant to the Throttle Body, yet '96+ 3100s do.

There is a lot that plays into MPG. Some of it can be the tune on the car. Such as your car Hiroska I believe has DOD (which is a system GM designed to help conserve fuel when it's not needed). Also, your tune may handle increased levels of ethanol better than the older Montes.

Again, there are so many variables that can impact MPG. It's not one single item.

 

So, what do you think is an overall look to see whats a good way to increase MPG? And have you heard of any "DECENT" increases on MPG? Supposely CAIS supposed to increase it by atleast 2 mpg? If im not mistaken? I cant rememeber so dont hold me to that. But what about changing out spark plugs? Lowering weight of the car? Lowering the car to the ground? What type of geographics have you heard to increase mpg? I would trust my monte has enough hp...well, not really ahahah, but you know what I mean, if HP is sitting minimal, what areas can MPG be improved in? I kind of hate DOD, it really doesnt help so much, but then again sometimes depending on how im driving, it does.

 

When you look at mods, like a CAI, they almost all make the promise of some type of a gain (HP, MPG or both). If those mods were truly tested in a controlled fashion, then they would have additional data to go with them regarding those claims.... Such as, "increased MPG based on highway driving and average outside temp being X" or "increased HP on this part of the power/RPM band", etc. It would also help to know about the control vehicle (make/model/drivetrain).

Lowering weight I don't think ever works against MPG or HP (but on icy roads, weight distribution to your drive wheels is important).

To be honest, I have spent more time trying to figure out how to go faster then I have on getting better MPG. I suppose the most important things would be:
- Buy gas from spots that use less ethanol additives (ethanol hurts MPG)
- Make sure the car is properly maintained (such as good plugs/wires, good suspension, proper tire inflation, ect).

But I don't know mods that would definitely improve MPG.