Quick MPG Question

[dynomax]

I am still in the process of going through the maintenance items on this truck, but maybe a little prioritization on the more important ones or where I might get an MPG gain. (The ironman lift is taking me off maintenance item course ;P) New spark plugs don't look as cool as 1.5"

 

I just fueled up, I reset my trim meter every tank and always check it (don't log it, just mentally).

25.2L/100KM, thats 9.29US MPG. These last 2 tanks I went back to 87octane, typically I run 91 (we have ethanol in our 87 at 10%, but not in the 91octane)

Same driving, with 91octane 22-23L/100KM (10.5USMPG). I do all city driving, just the odd bypass here and there, but we'll call it all city.

 

Summertime, I get 19L/100KM (thats 12.3US MPG) all city

Last big trip all highway was 14.5L/100KM(16US MPG) avg (45mph roads and 65mph road mix)

 

2004 Chinook 3.5L Automatic 4x4

Auto hubs

Run synthetic motor oil

air filter is new

fuel filter is brand new

MAF cleaned

plugs are original with 130k kms on them (80k mi)

i'll assume everything else is original also

tires a a bit over stock (245/75/16 vs 70/16) probally not enough to affect mileage too much

no CEL (Ever since I've had it)

Comes up to temp really well

 

Next on my list in this order are new plugs -- Do these really last 100k mi???? (ngk 6240's) and

transmission fluid drain fill with mobil 1 synthetic), and diffs w/ synthetic

 

So is my mileage abnormal, or is there a quick fix for MPG or am I getting what everyone else gets?

Edited February 25, 2012 by dynomax

[pathfounder]

9.3mpg out of the VQ is horrible.

[devonianwalk]

I agree. 9.3 mpg is very bad. I did a tune up this past summer and average 15.8 mpg's (with mostly highway speeds and my manual hubs unlocked).

Edited February 25, 2012 by devonianwalk

[Towncivilian]

I get 17MPG with 100% city driving with my 2WD, those with 4WD get 15-16 around town I think. 9.3 MPG is pathetic.

 

Stick with 91 octane, it's ethanol free as you say and the engine prefers 91+ octane anyway.

 

Make sure your SES bulb isn't burnt out. Engage the parking brake and set ignition to "ON" and make sure the bulb lights up.

Edited February 25, 2012 by Towncivilian

[dynomax]

I get 17MPG with 100% city driving with my 2WD, those with 4WD get 15-16 around town I think. 9.3 MPG is pathetic.

 

Stick with 91 octane, it's ethanol free as you say and the engine prefers 91+ octane anyway.

 

Make sure your SES bulb isn't burnt out. Engage the parking brake and set ignition to "ON" and make sure the bulb lights up.

 

 

Just did that actually. I reset the ECU following some instructions on another board also. Over on thenissanpath, i used the 1st reset option. not sure what that will do if anything.

[Towncivilian]

This is unrelated, but it would be more beneficial and less wasteful (over time) to do a complete fluid exchange of the transmission using the cooler return line, rather than one or more drain & fills. Here are instructions on how to perform a cooler line exchange:

 

You will need:

• 12 to 15 quarts of automatic transmission fluid
  
• A clear gallon jug, something like an empty milk jug
  
• Another large container to store used fluid for disposal

1. Disconnect the transmission cooler return line and secure it in a collection bucket such as a clear gallon milk jug. This will be the hose on the passenger side of the vehicle; disconnect the end leading towards the transmission.

2. Have a helper start the car while you watch the bucket - once it's half full (2 quarts), yell for the helper to stop the engine.

3. Add 2 quarts of ATF through the transmission dipstick.

4. Drain collection jug into larger jug (i.e. a Disposoil - these only hold 10 quarts though in my experience, so have something else to hold the last 5 quarts).

5. Repeat steps 2-4 until you're out of ATF.

6. Check fluid for proper level (see the next question and answer for details), and recycle the old ATF. Any place that takes used oil will likely recycle ATF.

 

I'd also strongly consider installing a Magnefine in-line filter. The Magnefine contains a very strong magnet to catch all ferrous wear material, and filtering media in the range of 35 microns to catch anything non-ferrous. A 3/8" Magnefine will fit the OEM transmission cooler hose. See a Magnefine filter in use for 23,000 miles opened here.

[Howie]

That's horrible mileage. I have a 2001 VQ manual tramsission 4WD with over 140,000 miles on it, and I get 15-16 mpg with hubs locked in the winter, 17-18 with hubs unlocked in the summer.

[WOT]

This is unrelated, but it would be more beneficial and less wasteful (over time) to do a complete fluid exchange of the transmission using the cooler return line, rather than one or more drain & fills. Here are instructions on how to perform a cooler line exchange:

 

You will need:

• 12 to 15 quarts of automatic transmission fluid
  
• A clear gallon jug, something like an empty milk jug
  
• Another large container to store used fluid for disposal

1. Disconnect the transmission cooler return line and secure it in a collection bucket such as a clear gallon milk jug. This will be the hose on the passenger side of the vehicle; disconnect the end leading towards the transmission.

2. Have a helper start the car while you watch the bucket - once it's half full (2 quarts), yell for the helper to stop the engine.

3. Add 2 quarts of ATF through the transmission dipstick.

4. Drain collection jug into larger jug (i.e. a Disposoil - these only hold 10 quarts though in my experience, so have something else to hold the last 5 quarts).

5. Repeat steps 2-4 until you're out of ATF.

6. Check fluid for proper level (see the next question and answer for details), and recycle the old ATF. Any place that takes used oil will likely recycle ATF.

 

I'd also strongly consider installing a Magnefine in-line filter. The Magnefine contains a very strong magnet to catch all ferrous wear material, and filtering media in the range of 35 microns to catch anything non-ferrous. A 3/8" Magnefine will fit the OEM transmission cooler hose. See a Magnefine filter in use for 23,000 miles opened here.

 

I want to do this now!! Seems fairly simple

[dynomax]

I want to do this now!! Seems fairly simple

 

I just did this last night with mobil 1 synthetic. i am sure this truck never had it changed yet (80K mi).

 

Took it for a drive, it used to hang 3-4 shift, doesnt now, and is just smoother all around.

 

old fluid looked the color of slightly used motor oil.

 

I would have done the drain and fill if i thought it had been taken care of every 30k mi, but i don't think it has been!

 

I am going to carry on with drain and fill in the future now that I am full of synthetic.

Edited February 27, 2012 by dynomax

[dynomax]

That's horrible mileage. I have a 2001 VQ manual tramsission 4WD with over 140,000 miles on it, and I get 15-16 mpg with hubs locked in the winter, 17-18 with hubs unlocked in the summer.

 

Just filled up again with 91 octane, put 60miles on it, still getting 21.3L/100KM (11.04US MPG).

 

This is after my fresh mobil 1 synthetic oil change 5w30, fresh mobil 1 ATF swap, cleaned MAF again, and did the ECU reset. No CEL

 

My next move are plugs (80K on originals)? am i missing something?

 

I have the diffs on my list too but i can't see that being substantial in making MPG gains?

[albino]

I really wish I had read this two days ago before I did the drain and fill! I might have to get one of the magnefine filters though. It seems like a pretty easy/cheap install with great results. A significant amount of fluid won't come out of the transmission cooler lines unless the engine is running correct?

[pathfounder]

I really wish I had read this two days ago before I did the drain and fill! I might have to get one of the magnefine filters though. It seems like a pretty easy/cheap install with great results. A significant amount of fluid won't come out of the transmission cooler lines unless the engine is running correct?

 

The pump is run by the input shaft, so yeah, the engine must be running.

 

Anything that comes out with the engine not running is just leaking out, really.

[Towncivilian]

And you can pinch the lines to have even less fluid leak out.

 

Synthetic fluid in the diffs will probably provide a small gain in MPG, maybe noticeable (but this is difficult due to all the variables). I'd still recommend it either way.

 

The spark plugs aren't due per the FSM at 80k, but replace them anyway. No harm in doing so, and it might help your MPG situation.

 

Don't forget to grease your driveshafts occasionally, too. Your 2004 wants plain NLGI #2 grease, it doesn't necessarily need to contain moly (strangely grease w/ moly was recommended up until 2003, when the recommendation changed for some reason). That probably won't help MPG any, but it's a good idea anyway.