drop in mpg???

[slowteg97]

has anybody noticed a drop in mpg after installing new sparkplugs???? my truck has 65k on it had oem plugs still in it and i noticed the mpg were slowly dropping so i replaced them with an ngk iridium plug, and set the gap to .044. i seem to have lost about 2mpg. the only other thing done to my truck is a k&n drop in and i removed the sulfer thing inside the intake box. i was getting 20mpg no matter how i drove now im down to 18???? any ideas????

 

[Nuke]

How many fill-ups are you basing the change on? I'd give it at least 4 or 6 before I make any judgements.

 

[Mirlen]

Most likely due to winter fuel mixture but there are other winter factors that will cut your MPG:

http://www.metrompg.com/posts/winter-mpg.htm

 

[slowteg97]

yea , thats what i was figuring maybe something with fuel probably got a bad batch or something just kinda wierd cause it happened out of the blue but im just about through this tank and the mpg came up slightly already so ill fill up at a different station and see what happens. thanks for the replys

 

[love4runnin]

i'm from NJ as well and have 63K on my v8 Sport all stock motor and every winter I notice a drop in mileage. No matter what station I fill up at nor what type of fuel, I always drop 2 MPG. I attribute this to the fuel mix they add from November to late March because I always get back those 2 MPG's in April. Always.

 

[slowteg97]

thanks for the heads up with that, now i know what to expect.

 

[p nut]

Could be due to the spark plugs, too. If you noticed, the OEM plugs were dual prong. The iridiums you picked up are probably single prong. OEM manual specifically states that regular dual prong NGK/Denso should be used.

 

[slowteg97]

huh single prong dual prong???? ill be able to rule out fuel with in the next few days i m going to fill up again this morning seems like when i get gas a this certain sunoco my truck doesnt do to well but when i get it at the wawa down the road it fine i get 385 out of the tank vs 355 or 365 . the only thing i have noticed since the plugs was that the throttle response has improved and mid range power cause when passing people it pulls like a beast now.

 

[love4runnin]

I wouldn't go by your RANGE estimator, it's hardly rite. I would reset your trip odometer and go by that. The reason I say this is because my RANGE estimator usually tells me about 385 to 390 and i actually get 305 to 310 in the winter(Summer driving usually yields me about 365 to 370) but in the summer my RANGE says i should be getting 395 to 400.

 

[pickerdd]

You might also need to reset your truck's computer for it to register the change of the spark plugs.

When I changed the plugs in my old 4Runner the gas mileage decreased quite a bit until I reset the computer. It was also a good time to adjust my driving habits.

 

[Nuke]

The on-board computer does NOT accurately calculate MPG or range. Although it uses an accurate value for your distance traveled, the number of gallons it uses is imprecise. Hand calculate your gas mileage. It's the only way to get accurate numbers. The on-board info is good RELATIVE info only.

 

[Annoyed]

i'm from NJ as well and have 63K on my v8 Sport all stock motor and every winter I notice a drop in mileage. No matter what station I fill up at nor what type of fuel, I always drop 2 MPG. I attribute this to the fuel mix they add from November to late March because I always get back those 2 MPG's in April. Always.

Cold weather will ALWAYS result in a drop in mileage. Colder air is more dense; it contains more oxygen atoms than warmer air. As a result, the engine must use more fuel to maintain the ideal air/fuel ratio. In older cars, this was done simply by the more dense air created higher vacuum, drawing more fuel thru the carb. jets. In modern engines, the control computer does it. This will also result in a small increase in power output but not enough to see it. Also, cold weather requires even richer mixtures during start & warm up, which take longer in colder weather.

 

[slowteg97]

ok turns out i got a batch of bad gas cause after about 10 miles on a fresh tank im getting better mpg then before. i use the actual trip meter to figure my mpg which i use to get about 19.5 and 385 out of the tank. i know what ur sayin about that other thing cause when i fill up it will say anywhere from 400-420 which i know wont happen but i slowly drops as i drive and seems to be more accurate as i get lower on fuel. the only time i use the mpg calculator in the truck is to pretty much determine how my truck is running is use to read 20.9 21.5 usually and when i dropped to 17.9 i knew something was up. i know that thing is not accurate but it will let you know if something is going on with your motor. but like i said it seems to be alot better now with the fresh gas and now i can see how much the plugs have done for me cause now that thing reads 21.8- 22.6 once again isnt accurate BUT it lets me know my truck is running alot better.