So I Changed out my Spark plugs yesterday and found that 2 of my coil packs on the driver side was nicely coated with oil, which means my valve cover or gasket has to be replaced (can someone shed some light on that, Im not to sure). But one of the main reasons why I changed the plugs was with hopes that my MPG will change A little. It shows that i averaged 10.8MPG before and now after the spark plugs were changed it went down to 8.7MPG .... has anyone had this issue? will replacing the valve covers solve it?

 

Is the CEL on?

Also make sure you didn't accidentally switch the connectors for plugs 4 & 6. a very common mistake that can lead to a misfire and lowered MPG

 

I double checked the connectors and its fine, Ive had no warning lights either.

 

how did the plugs look when you took them out and how do the new ones look after the swap

 

I find it hard to believe that you can get that kind of MPG without a fuel leak. Your cat converters would be on fire by now if it was going down the tailpipe. Even when I run wide open all day (Raging Bull Run), I still get almost 14mpg.

 

well the 3 old plugs on the passenger side showed signs of normal wear (black with some carbon buildup) but 2 of the 3 plugs on the drivers side had oil on the coil pack and the plugs.

 

If i can get 14mpg i'll be happy. I'm currently dropped on H&R's and I have some negative camber all around so i need a camber kit. But that shouldn't affect my MPG so bad.

 

Is this what the cars computer is telling you? Does 10.8 mpg seem accurate with how many miles you are getting per tank? Maybe your computer is messed up.

 

Yeah, the info is based of the computer's readings.

 

Calculate your MPG by gallons used and mileage driven. I don't even come close to 8mpg.

 

Approximately how many miles are you getting per tank? I get about 23 mpg, refill at 1/4 tank and have gone about 360 miles at that point. I have 142k on my car by the way.

 

http://yhst-13387653796039.stores.ya...nivqvacor.html

 

8mpg is binge drinkingggggg

 

Yes, it will. Your alligment being off has a HUGE impact on your mileage dude.


You cannot go off the on-board readings. Do nothing until you get ACTUAL readings by calculating Miles travelled per Gallon consumed. Also, you didn't say what sized tires you have, are they the same diameter as stock?

Do the calculation for MPG by:

1. Fill the tank. Note where you fill up, you'll want to return to the same pump if possible.
2. RESET your TRIP odometer on your dash.
3. Drive for however long you like. It's recommended to run close to empty so you get an accurate idea of fuel consumed across a tank.
4. Return to the same pump and fill up again. Record Gallons to 'full'. Record Miles travelled from TRIP odometer
5. Divide miles travelled (TRIP mileage) by Gallons used
6. Now you have your ACTUAL mileage. Repeat this if you like a few times to get a more accurate average mileage.

Example:

1. Full tank
2. TRIP = 0
3. Almost empty tank
4. Filled tank.
350 Miles travelled on TRIP
20 Gallons to fill up tank
5 350 / 20 = 17.5
6. 17.5 MPG

^^Are the VC's that expensive???? The Maxima's (6th gen version) are only like $30-40 for the whole thing with built in new seals........ just curious.

 

Yes, they are 2-3 hundred each I believe.