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Terrible gas mileage V-6


redskinman

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I've probably only put about 6 or 7 hundred miles on rig since buying it and it's gotten terrible gas mileage. I was blaming it on the misfire I had but since replacing fuel injs and fixing misfire it hasn't gotten any better. Filled it up after fixing misfire, after driving it home from shop yesterday {getting valves adjusted} it was down to almost 1/4 tank so I filled it up again. It only went 94 miles on 3/4 tank for little under 10 mpg, that sucks!! One of the main reasons for buying this rig was for gas mileage, I wasn't expecting 20 mpg but I was expecting 12-13 at the very very least and hoping for 14-15 mpg. I would say 75% of this latest tank was highway miles. It's got new plugs, wires, pcv valve, fuel filter, new wires, new fuel injs, new distributor and cap, there's no reason for this bad of gas mileage, it's not even weighted down yet for a road trip. What the heck?

I am not using overdrive at all, which I guess would improve gas mileage some. I've read many posts about using overdrive with most being don't use it, but a recent facebook post was talking about it and everyone said if you have a V-6 leave it in OD all the time UNLESS the load on it is constantly shifting in and out of gear. So should I leave it in OD and how much better do you think that's going to improve gas mileage?

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I don't keep track of my MPG but I know it is over 10! When I did check my millage, just a bit under 10 was the worst I got going up into the mountains with a head wind and OD off.    Overdrive = 4th gear, why would people say not to use 4th gear?   If it is lugging or shifting in and out I turn it off and go to third gear or Drive as it is labeled.

Only my opinion.    Jim

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Go ahead and use overdrive on the highway. The V6 has a locking torque converter so there is no problem with heat build up in the trannie. No 4th is a 4 cylinder thing that doesn't have the locking torque converter No hills turn off ECT button too

Linda S

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The question could also be how long was it run with crappy injectors. if fuel and sludge has built up on the porting of the head and coked up the exhaust paths and gunked things up; its possible its reduced some efficiency.

couple other easy things to check

- make sure air filter is new

make sure tires are aired up well

- make sure you don't have stuck calipers

 

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x2

Plus you really need to take a trip, 500mi or so, keep track of the actual miles and actual gal used.

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16 hours ago, Totem said:

The question could also be how long was it run with crappy injectors. if fuel and sludge has built up on the porting of the head and coked up the exhaust paths and gunked things up; its possible its reduced some efficiency.

couple other easy things to check

- make sure air filter is new

make sure tires are aired up well

- make sure you don't have stuck calipers

 

Forgot to mention air filter is new, haven't checked tires they're brand new but that doesn't mean they were filled correctly.

it's getting its maiden camping voyage this weekend only I won't be the one driving it or camping in it, my daughter will be. I'm going to leave it out of OD because I don't trust her to know when to turn it off if it's getting a load on it.

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If the oxygen sensor goes bad the ECU no longer advances timing. Any check engine light or code?

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21 minutes ago, Skydancer2992 said:

If the oxygen sensor goes bad the ECU no longer advances timing. Any check engine light or code?

No

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13 hours ago, redskinman said:

Forgot to mention air filter is new, haven't checked tires they're brand new but that doesn't mean they were filled correctly.

it's getting its maiden camping voyage this weekend only I won't be the one driving it or camping in it, my daughter will be. I'm going to leave it out of OD because I don't trust her to know when to turn it off if it's getting a load on it.

Air pressure is very important I ran 50 all around in mine. It's a brick as Linda said speed, I have a fancy engine OBD2 reader in my Tacoma that plots all kind of things including average mileage if I'm towing my camper the difference between 60 and 65 is about 1.5 mpg and at 70 I'm down close to 3. 

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3 hours ago, Maineah said:

Air pressure is very important I ran 50 all around in mine. It's a brick as Linda said speed, I have a fancy engine OBD2 reader in my Tacoma that plots all kind of things including average mileage if I'm towing my camper the difference between 60 and 65 is about 1.5 mpg and at 70 I'm down close to 3. 

Very refreshing to see someone not running 60+ PSI in their tires besides me. :P

 

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15 hours ago, linda s said:

So how fast are you driving. Anything over 65 will definitely drop the mileage severely.

Linda S

I would say 60-70.mostly 65 range

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19 hours ago, Totem said:

The question could also be how long was it run with crappy injectors. if fuel and sludge has built up on the porting of the head and coked up the exhaust paths and gunked things up; its possible its reduced some efficiency.

couple other easy things to check

- make sure air filter is new

make sure tires are aired up well

- make sure you don't have stuck calipers

 

Is that something shop should have noticed when doing valve adjustment?

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i returned from two small trips taken over the last 10 days. both trips were NON INTERSTATE I AVERAGED 12.5 TO 13MPG

Edited by hunkaman
STOPPED TOO SOON
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I regularly get about 13mpg in my V6, but I stay close to 60mph and keep tires between 55-60psi. I only turn O/D off on hills, and if I leave it off for long, mileage will drop to 10 pretty quickly. So... you're not far off the mark. 

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13 hours ago, Ctgriffi said:

I regularly get about 13mpg in my V6, but I stay close to 60mph and keep tires between 55-60psi. I only turn O/D off on hills, and if I leave it off for long, mileage will drop to 10 pretty quickly. So... you're not far off the mark. 

Ok :D

So next trip I will take everyones advice and report back,thanks

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23 hours ago, redskinman said:

Is that something shop should have noticed when doing valve adjustment?

a valve job wouldnt be a port n polish job, which would involve removing and steam cleaning the head. They should have reported it if it looked bad.

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23 hours ago, redskinman said:

Is that something shop should have noticed when doing valve adjustment?

I'd have to say no if all you took it in for was to adjust the valves. Doing this job does not require removing the heads so he's not going to see any internal problems other than what's visible removing the valve covers.

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everyone is throwing ideas out there.  I would look for a vacuum leak - something like the PCV hose off can make these things run like crap. 

basic tune-up - yah makes a lot of sense.   adjusting valves - I would put that further down the list due to cost.

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  • 5 weeks later...

I just did a 3000 mile trip from California to Utah and back. I tracked mileage throughout and am pretty consistent at 12.5MPG. I run tires at 50psi and generally 55 to 60MPH.

Note that I run pretty heavy (full water tank, partially full waste tanks, two adults, kid and dog + lots of cargo). Also lots of mountains on this trip (constantly going up and down).

Edited by Mark Krueger
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It's refreshing to finally hear some accurate and not exaggerated MPG's. I have difficulty believing others claiming to get 15 to 16 MPG in their 6 bangers. I get a little over 14 MPG in my 4 banger fully loaded light pedal 57 MPH OD on flats and downhill only on freeways and many back roads. 

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8 hours ago, jjrbus said:

My V6 will get 15-18 mpg,  <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< When I put it up for sale  :rolleyes:

Aint that the truth!!!

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What I have found it does not matter what you are driving/towing 10 to 14 at highway speed is about it for an RV. unless you are on back flat roads doing 50 max. It's no wonder big jet aircraft  burn 9 ton's of fuel and hour!

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I wish I could slow down and get the numbers I hear about, I'm normally on the interstates doing 70+ and still getting passed.  That is why I don't keep tract of MPG, if I knew what it is,  I would quit driving the Toy.

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11 minutes ago, jjrbus said:

I wish I could slow down and get the numbers I hear about, I'm normally on the interstates doing 70+ and still getting passed. 

Ya'll better stay on the East Coast ;). The speed limit on most of Wy interstates is 80, Utah/MT too. You havent lived untill you have a set of Rocky Mt. triples blow past at 80+. They snake a bit in a cross wind. :blink::blink:

 

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Must be a man thing. I piddle along and let people pass me, why would I care. Have never gotten honked at or the flying finger ever. On smaller roads I pull over as soon as I can to let people by. Speed limit on highway 5 in Cal is 70. I'm usually going 55. It's amazing, I still get where I'm going. Ya know there are still old VW buses out there and I can easily pass them. In fact out here in California they go for more than my Sunrader, way more

Linda S

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I think its a retired or independent wealth thing vs. employed thing... the retired or indys have all the time in the world and go at their pace. The employed only have a couple days paid vacation to burn which demands results in being places by certain times and home again in order to go back to work for the man. So yup a man thing.  :)

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14 hours ago, WME said:

Ya'll better stay on the East Coast ;). The speed limit on most of Wy interstates is 80, Utah/MT too. You haven't lived until you have a set of Rocky Mt. triples blow past at 80+. They snake a bit in a cross wind. :blink::blink:

 

A while back I posted a picture of one of your speed limit signs, thought it was the route # at first :o      We have the bulk of the nations retired people here in Florida so they keep the limit at 70 for the old folk. 

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A 400 mile trip, 70 mph around 5.7 hours 60 mph 6.8 hours about 8 less gallons of gas what's the rush? Enjoy the ride.

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Well to update this on my rig,took my first camping trip in it,packing lightly just for 1 night.Drove from cypress to galveston{86 miles}used 1/2 tank of gas.had OD on,High speed of 62 most of the time going between 50-60 because it was raining most of the way.Got not quite 12 mpg on that run.After filling it up put 148 miles on it till tank was near empty,average of 10.5 mpg{but I did run generator for about 4 hrs,not sure how much gas gen drinks}A little better then before but still disappointing  numbers to me:(.

Love my toyhome but looks like I should have done a lot more research,like jjrbus said,when these are being sold the mpg numbers are inflated and I bought into the hype.If I would have known actual mpgs on these rigs I would have tried to get a smaller motorhome with a v-8 so I could pull what I needed behind it.

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4 hours ago, Maineah said:

A 400 mile trip, 70 mph around 5.7 hours 60 mph 6.8 hours about 8 less gallons of gas what's the rush? Enjoy the ride.

often times the water park, front desk office hours, etc.  is closed by that hour,  Now imagine a 1200 mile trip...4 hours.

Gas is only $2 bucks and change; to the working man that has good paychecks but little time - time is worth more than money.

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