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My Chrysler Grand Voyager LX 3.3, 2006 model, 36.000 km is new to me this spring. From highway driving (60 m/h) the trip computer reports 24 MPG, I expect 22 -23 from experience with my previous -96 Voyager 3.3, but the actual consumption is 19 MPG. Converted to US Gallon.

Can the computer be "that" wrong?

Is that poor mileage usual on 2006 model?

I have had the car to service while troubleshooting this situation, and they say "no error" and upgraded software.

What could typical be wrong in fuel system?

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Chrysler Grand Voyager LX 3.3, 2006 model, 36.000 km
 

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>Can the computer be "that" wrong?<

Nope but YOU can be and probably are

>Is that poor mileage usual on 2006 model?<

Nope you're absolutely normal, well........................the van anyway

>I have had the car to service while troubleshooting this situation, and they say "no error" and upgraded software.<

What a waste of time

>What could typical be wrong in fuel system?<

Absolutely nothing
 

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Hey there, welcome to the forum!

My Chrysler Grand Voyager LX 3.3, 2006 model, 36.000 km is new to me this spring. From highway driving (60 m/h) the trip computer reports 24 MPG, I expect 22 -23 from experience with my previous -96 Voyager 3.3, but the actual consumption is 19 MPG. Converted to US Gallon.

Can the computer be "that" wrong?

Is that poor mileage usual on 2006 model?

I have had the car to service while troubleshooting this situation, and they say "no error" and upgraded software.

What could typical be wrong in fuel system?
The computer shouldn't be that far off. I would wait and average your MPG over the next few tanks, and compare it to the computer. Make sure you reset the AVG MPG computer when you fill up, and fill all the way up (no half tanks). Also reset your trip odometer. At the end of the tank, when you fill up again, write down what the AVG MPG computer says, and then hand calculate your MPG with distance driven (for us, miles) divided by fuel used (for us, gallons).

I would also be careful and make sure you calculate imperial gallons to US gallons correctly, and/or that a conversion even needs to be made (I'm not sure if it does or not).

For a highway trip, the 24 MPG your computer is calculating sounds about right. 19 MPG sounds too low. But a lot depends on a lot of factors. As I said, I'd wait and average a few more tanks and then check and see where you are.
 

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check the mileage at each fill up and do the math that way. The computers are allowed to have some error and they measure fuel usage as a correlation to throttle (how much fuel is metered at a given time, over time) as I understand it.

Your numbers are not to far off anyway. These are big, heavy vehicles. Combined we see 18-22 mpg depending on the proportion of city to highway mileage.
 

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My Chrysler Grand Voyager LX 3.3, 2006 model, 36.000 km is new to me this spring. From highway driving (60 m/h) the trip computer reports 24 MPG, I expect 22 -23 from experience with my previous -96 Voyager 3.3, but the actual consumption is 19 MPG. Converted to US Gallon.

Can the computer be "that" wrong?

Is that poor mileage usual on 2006 model?

I have had the car to service while troubleshooting this situation, and they say "no error" and upgraded software.

What could typical be wrong in fuel system?

:hi2: Sagacar and welcome to the Chrysler Minivan Fan Club Forum. We hope your experience here is a pleasant one. Following are some tips to help with giving / receiving information, but firstly, your mpg problem.

- Perhaps your computer is already using US gallons rather than miles per Imperial gallon.
- The conversion mpig to mpg is 0.83. So, 24 mpig X .83 = 19.9 mpg whereas you show 19.
- Common factors affecting highway gas mileage are driving style, terrain, wind conditions, speed, load in / on the vehicle, and air pressure in the tires.
- 23-24 miles per US gallon sounds right (expected) for your vehicle

Jason's suggestion is what I would do. My computer often shows higher, by a mpig or two, than calculated from fillups.

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check the mileage at each fill up and do the math that way. The computers are allowed to have some error and they measure fuel usage as a correlation to throttle (how much fuel is metered at a given time, over time) as I understand it.
This is correct. The computer knows how much fuel it has commanded the engine to use, through the fuel injectors. The injectors are PWM, that is Pulse Width Modulated, so there's a very definite open and closed state. When they're open, fuel flows. When they're closed, fuel doesn't. At least that's how it's supposed to work.

Anything in the fuel system that's not up to snuff can cause you to use more fuel than your computer thinks you're using. Perhaps you have a leaky fuel injector. If fuel is leaking through the injector when the injector is closed, the computer won't know it. There may also be a leak in a line somewhere. It's also possible that the fuel pressure is not correct.

Again, though, to the original poster, I'd check over 3 or 4 or 5 tanks and then reassess.
 

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Discussion Starter #7
More info on situation

Again, though, to the original poster, I'd check over 3 or 4 or 5 tanks and then reassess.
Thank for a lot of tips.

I have measured 5 - 6 times already - full tank, read trip counter for distance (and it is checked OK with the actual distance) and use calculator. I do think that part is under control. I run the trip computer in metric mode. So also do I usually compare mileage as liter pr 10 kilometer. My previous 1996 Voyager 3.3, 180.000 km was fine at the same trip with 9,7 +/- liter pr 100 km. The brochure from 2006 says 10,5 liter and I measure 12,5 liter pr 100 km :confused: .

I usually not use A/C and I have checked the airpressure in tires. I like to have about 55 - 60 mph during this "tests" and the area is rather flat, at least compared to what it can be here in the Nordic countries.

I still have 2 months left of Warranty. My problem is that the service /salesman says 12 -13 liter pr 100 km is normal for highway (18 MPG/US). They have checked for errorcode with computer and here they stop.

Hope for solution before warranty runs out.

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Sagacar
2006 Chrysler Grand Voyager 3.3 LX, 36.000 km
Former: 1996 Chrysler Grand Voyager 3.3 SE, 180.000 km
 

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I would not consider 18 MPG to be normal for only highway, not under the conditions you're describing (flat, 55-60 MPH, etc). Do you let the van warm up a lot before driving off? Or does it sit and idle often otherwise?

The brochure may say 10.5 liters per 10 KM, but that would be a "highway only" measurement. You are measuring the entire tank, with everything combined (cold starting, town driving, highway driving, etc). How much of your driving is sustained at a constant 55-60 MPH, and how much is around town. My bet is that more of your driving is at a slower speed than you probably think. 18 MPG is not a bad average for a "combined" measurement, say 50% town and 50% highway. But if you're filling up before getting on the highway, driving for a full tank on the highway, getting off, then filling back up, 18 MPG sounds pretty low for that.
 

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:Wow1:
Anything in the fuel system that's not up to snuff can cause you to use more fuel than your computer thinks you're using. Perhaps you have a leaky fuel injector. If fuel is leaking through the injector when the injector is closed, the computer won't know it. There may also be a leak in a line somewhere. It's also possible that the fuel pressure is not correct.

Again, though, to the original poster, I'd check over 3 or 4 or 5 tanks and then reassess.
Very true but any half decent tech should be able to find that fairly easy.
The computer will show the fuel trim being leaned out from normal.

EPA says 17 MPG City and 24 Hwy and 20 combined.
This is for regular gas. Gas with ethanol will be slightly lower.

I'm pretty sure your trip computer is already MPG US galons not Imperial.
My Van computes pretty close to what I work it out to manually.
 

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Discussion Starter #10
Low MPG, more info and new testdrive.

Up til 4 tankfills ago I measured the mileage and actual litre and have had a range of 1,2 liter/10 km (19MPG) til up to 1,55 liter /10 km (16MPG) correlated to highway versus mixed driving. Nice correlation but too high level at highway, espacially when I compare to my previous 3.3 litres (Grand Voyager 3.3 1996 - owned it for 12 years). I live in Nordic country so meter is metric and computer shows liter/10 km. or liter/100km. During this time I read that the tripcomputer mileage pr liter often was real off compared to actual consum. However liter/10km was so high that I started more structured troubleshooting and talked to service people and owners to here what theire experience was.

Three tankfillings ago I twisted the sparkwires and just checked that thing was visual OK with wires etc.. Then I got 1,05 liter/10 km (23 MPG) at first time :biggrin: (measured usage/distance) and thought I found the error (80% distance highway (three trips of 100 km = 300 km) + town 140 km 14 trips of 10 km town). The next measurement was then a bad experience again. This was realy highway - 440 km nice highway with 4 pitstops, 3 with warm engine and one with cold engine, and one 10 km smooth urban drive. The MPG was then "back" 1,23 liter/10 km (19 MPG). That was the time I made this post.

I have been driving another car during the weekdays but now I tried a new experiment directly after the mentioned 1,23 (19 MPG) measurements: I ended that with filling the tank full and drove to parkinglot 11 km with warm engine. Yesterday I pulled off every wire, in both end, looked after it was clean and "twisted" them back. And then I drove 96 km highway - extremely smooth 55 - 60 mph., no load, no A/C, I then stopped at the gas station at home and filled 6,73 liter. This means 6,75 /107 > 33 MPG. This can be wrong of course since so small distance, but when I was filling up I was expecting at least 10 liters at the best when I was tanking, so I checked: the gas was coming out of the tankhose after several toppings and I saw gas was all the way up through the hose.

The computer said 0,87 liter/ 10 km (27 MPG) (lowest ever - reset just before test drive) and DTE was 600 km before filling up. This combined with the meter still at "full" before filling up makes me believe in this measurement. (The tankmeter shows a little over "full" when full). At least it must be much better than the regular "1,2 /19 MPG)" (the difference is 5,3 litres at this distance)

Of course I still have to get this confirmed but my theory is that there is something wrong with wires and/or spark combination, and that it get worse rather soon after getting good contact, or wires that somehow gives bad ignition. I do also feel small misfires typical around 40 miles/hour and running "idle" and cold engine, no error code. Kind of disappear when higher rev or accelaration. The car has 36 000 km on meter.

Is there any other experience that can help me supporting this theory?

I will probably change the wires just to be safe that they don't cause the situation. Is there any special recommendation on type of wires or sparkplugs for "this" situation? :help_wsig

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Chrysler Grand Voyager 3.3 LX, 2006 , 34.000 km
Sagacar
 

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Probably 19 hwy is about right if there were any stops at gas stations, stop signs etc. If you get out on level road and reset the thing at 60 or 70, whatever you want to do, it will tell you what you are actually doing on the highway. But stop once or twice and you will see how dramatically just a few stops impact mileage ratings. I would guess that you pure h/w mileage is like 24-25 mpg, around town 15-18. I have had two vans and that is what they average. If you notice anything dramatically change, check out the O2 sensor, I had one go from 20 to 12 mpg overnight after mine got hit, but no check engine light came on. Changing it reversed it change. I find my computer routinely is a mile or two high on its estimate.
 

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I just did a trip this weekend. The first tank was driving up to Virginia, mostly interstate, speeds of 75-85 the whole way, and then shuttin' it down in Virginia and doing a lot of local mountain driving where my folks-in-law live. Average that tank, for the whole tank, was about 21 (manual). I reset the computer a number of times during the trip to check shorter durations of economy. I was getting better mileage driving 75-80 without cruise than I was doing 60-65 with cruise.

On the drive back down yesterday, I only burned about 1/4 tank indicated (filled when we left) and the overhead computer showed 24.4 MPG. But since I burned so little fuel, I haven't filled it to manually check against the computer. But my manual calcs are always pretty close to the computer.
 
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