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

[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 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.

[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.

[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.

[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.

Yeah, it could just be one of those "Jeep things you wouldn't understand"... 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!

[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