Average..........MPG

[JHarris1385]

Just wondering what everyone on here is getting.

I have a current new low total of........9.3mpg for the last tank of mainly highway driving.....

This has been a problem of mine for a while now. My CEL will not go off for any reason. I have even installed a brand new MAF.

This all happened after power washing under the hood. With the lift and 9mpg its starting to REALLY hurt.

[etlsport]

what size tires did you end up with? larger tires will hurt your mpg.. make sure the shop inflated them properly as well, i know that low tire pressure can destroy your gas mileage (as much as 15% i hear) also maybe have your brakes checked to make sure they arent contacting the wheel during normal driving

[JHarris1385]

P265/75-16.....31.6'' i think

They look like they could use a little more air but not much. How much psi is too much in those?

[etlsport]

The best way to figure out what pressure to run in your tires is to take a tire chalk and put a straight line across the tread. Drive a short distance and check the line. If it has wore off in the center of the tire then you have too much air. If it is wore off on the edges of the tread then you do not have enough pressure. The line should wear evenly across the entire surface of the tread.

quoted from a jeep tip guide for aftermarket tires

http://www.ajeepthing.com/tire-maintenance.html

[JHarris1385]

I dropped three mpg after the lift. But I knew that was coming but during the lift. I also got a diag on it that assured me it was a faulty MAF sensor promising me to bump back up to near normal mpg, and clear the Check Engine Light. But $140 (MAF) + $80 (diag) later I still have piss poor mpg and a CEL...

[etlsport]

id invest in a scan tool of some kind (id recommend scangauge II from tone) for 160 u get the ability to read your own codes and lots of other engine vitals

as for the mpg i dunno what to tell you.. sounds like its getting progressively worse? which would mean somethin clogged and getting more clogged.. fuel filter.. air filter.. egr.. for now id probably remove the roof rack and fairing and window deflectors if youve got them as they are just adding drag.. and sounds like until you figure the problem out u need as much aerodynamics as you can get

[ZEUS]

Is it maybe a leak somewhere? The fuel lines are under a lot of pressure being fuel injected so things might not leak unless it's running. ????? :( ????? Your tires also alter your speedo and odometer so you might be getting worse than 9 mph in actuality... not that you wanted to hear that... sorry! I hope you get it figured out soon.

[Y33TREKker]

Do you have any kind of aftermarket air-filter/intake setup? Maybe the power washing got the element wet and it's creating too much restriction?

Or maybe the power washing made an O2 sensor go bad (hot exhaust - cold water).

If you're sure the power washing is what started the problem, what would other components could have been affected/altered by a high pressure stream of water?

[JHarris1385]

where is the o2 sensor?

I am throwing a multiple random cylinder misfire code.

[WILLY]

Power washing the engine compartment :eek: not a good idea,especially if the engine is hot,if you want to wash it do it when its cold or has only ran for a few minutes the do it with a gental spray not a full spray.

[Ldub]

Is it maybe a leak somewhere? Your tires also alter your speedo and odometer so you might be getting worse than 9 mph in actuality... not that you wanted to hear that... sorry! I hope you get it figured out soon.

Zeus,
Pardon me for sayin' so, but I've had a few fuel leak issues & if it was enough to decrease mileage, the olfactory sensor (nose ;) ) would pick it up.

As for tires...larger tires rotate fewer times per mile, putting less numbers on the odo. ...for a point of reference, 33's are about 10% larger than stock.
When I figure mileage, I add 10% to whatever's on the trip & then divide by gallons...& it's still pretty dismal. :rolleyes:

[Jolly Roger VX'er]

Just wondering what everyone on here is getting.

I have a current new low total of........9.3mpg for the last tank of mainly highway driving.....

This has been a problem of mine for a while now. My CEL will not go off for any reason. I have even installed a brand new MAF.

This all happened after power washing under the hood. With the lift and 9mpg its starting to REALLY hurt.

Bigger tires will surely cut the mileage down but not to the extent you have experienced. Tire pressure really seems to affect the mileage too. My original tires were always aired up to about 39-40 lbs with the tire stating like 44 lbs max if my memory is correct. My bigger Bridgestone Revo's are aired up to nearly 40 lbs too for max mpg. I suffered bad mileage a few years ago and changed out my Fuel Pressure Regulator and it raised my mileage up dramatically. Spazz suffered the same issue and changed his out too. Do a search for "Fuel Pressure Regulator" and see if any of this hits to home.

Also a few years back (I live on a dirt road!) I found out my rear calipers weren't releasing properly (dust in caliper sliders!) resulting in the inner pads "dragging" and wearing out prematurely as well as uneven wearing on that side of the rotor. It went unnoticed because since it was both the VX didn't pull to either side of the road while driving. I'm quite sure this didn't help my mpg either!

[Y33TREKker]

where is the o2 sensor?

I am throwing a multiple random cylinder misfire code.

I may have steered you in the wrong direction with that suggestion (O2 sensors). I was thinking of the O2 sensor locations on one of my other vehicles when that thought occured, but now that I've looked up the O2 sensor locations on a VX, I doubt that a high-pressure wash in the engine bay would have brought much water into contact with the O2 sensors. They're located more on the underside of the vehicle.

If I've interpreted the CD manual correctly, the cylinder misfire codes are based on crankshaft-position sensor (CPS - abbreviation) readings. These codes will be produced if the engine isn't running smoothly, which just causes the CPS to not be in the position it would/should normally be in when the readings are taken. In my opinion, that doesn't really narrow it down much though, because there are a few different things that can cause the engine to run rough in the first place.

I know the subject of spark plugs has been brought up. Have they been checked visually for cracks in the insulators, or possibly water in the spark plug wells? Those could cause misfires.

It may also be worthwhile to disconnect the crankshaft position sensor and apply some dielectric grease to the connector.

[JHarris1385]

So how would I get water out of the spark pulg wells.


Also where is the CP sensor?


Thanks.

[Y33TREKker]

So how would I get water out of the spark pulg wells.


Also where is the CP sensor?


Thanks.

Disconnect (-) battery cable, disconnect each ignition coil electrical connector, remove the two bolts that hold each ignition coil in place, then remove each ignition coil and spark plug boot by simultaneously pulling up and twisting back and forth the coil pack/plug boot assembly.

There may not be any water in the plug wells, but it should be plainly visible if there is any. Twisting up a paper towel and pushing it into the plug well would probably be enough to soak up any water that may be present. If there is any water present, you'd want to get it all soaked up before removing that spark plug.

The Crankshaft Position Sensor is located on the passengers' side of the engine block just to the rear of the motor mount.

Tones downloadable VX manual is located at the bottom of this page.

http://www.tonemonday.com/vxparts.html

The manual has a search feature that's very helpful too.

[ZEUS]

Zeus,
Pardon me for sayin' so, but I've had a few fuel leak issues & if it was enough to decrease mileage, the olfactory sensor (nose ;) ) would pick it up.:rolleyes:

Yeah, it could just be one of those "Jeep things you wouldn't understand"... :rolleyes: you get so accustomed to huffing fumes on the trail with the top off; it always smells like it's leaking! Of course, maybe it always is! :p

[etlsport]

im pretty sure ive got a fuel leak somewhere.. my scangauge tells me i got 17mpg.. calculations tell me i got a hair under 16

[Chopper]

Regularly get 18-20 or so but this is Fla. that is Phila. and things are way different... I am from Bucks Co. a lifetime ago. 16,17 is not unreasonable in the city.

[garfull]

15 on my 2 tanks since ive gotten the vx.

[Jolly Roger VX'er]

During the summer months I was averaging from 18.5 to 19.2 mpg in PA. With the fall/winter weather moving in I got 15.3 mpg this last fill-up. My Monte Carlo dropped too from 25 mpg during summer to around 22/23 mpg.