'01 3.3L Grand Caravan, poor gas mileage...

[Lscman]

I was all excited about the EPA highway fuel economy estimates for my '01...until I compared real-world readings to my old minivan....

I am real disappointed with the highway fuel mileage of my 3.3L '01 Grand Caravan. I consistently get between 19.5 and 20.5 MPG at steady speeds of 65-70 MPH with almost no cargo. It's city "putzing around" fuel mileage seems to be OK....around 17-18 MPG. The highway calculations are accurate & consistent. I used long trip (300+ mi) & full tank topoff methods, filled before and after on level ground, even same gas pump, using same methods.

Is this typical highway economy?? I was expecting 23-25 MPG. This vehicle runs smooth as glass and the OD and torque converter lockup is functioning properly. Never any engine trouble or warning lights. The vehicle coasts nicely, so brakes are not dragging. Tires always kept at 36 psi.

.......My 4 WD '92 Aerostar extended length minivan had a 4L, 4WD and steep 3.73 gears, yet...with it's inefficient shoebox shape, it got the same fuel economy. It got 18 city and 20 highway too! These vehicles weigh about the same.

[windsorboy]

Have a 2004 Grand Caravan SXT 3.8L... getting consistent 18MPG City, 19-23 Mixed, and 30-32 Highway. Something is up with your van.

[Lscman]

Your 4200lb van gets 30-32 MPG at 65-70 MPH...are you serious? With all due respect, I kinda doubt you're getting 7 MPG better than EPA rating. That'd be a first. My buddy's 2.4L std Caravan....it gets 28 MPG.

A 31 MPG value is higher than most 3.0L to 3.5L V6 sedans weighing 500 lbs less, with a roofline 2' lower.

Anybody else care to share what kind of economy they get at 65-70 MPH with either 6 cyl??

[windsorboy]

Sorry... my highway mileage is with Canadian conditions @ 100-110 Km/h (approx 55-60 MPH or so... we don't drive 75!!)... and doing that in my environment (dead flat... kinda like kansas)... I get 30-32 MPG... which is exactly what it is EPA rated for 19-32MPG (city/hwy) or thereabouts. City mileage is just that... pretty much 100% city, mixed driving is probably 40-60 (city/hwy) split. I'm not especially lead footed but then again I don't granny it either... however I do have it where the tranny is shifting conservatively.. these damn 41-TE's are fragile and I want mine to last. So yeah, in my world this is realistic... in your world... maybe not. It all depends on road grading (I'm dealing with 0%), traffic, driving style, gasoline (we have cleaner gas in Canada), speed limits, # of passengers, etc etc etc. The other guy's figures are extremely low IMHO and that is what I'd get driving foot to the floor 90% of the time LMAO.

[Lscman]

(going) approx 55-60 MPH or so... we don't drive 75...

I get 30-32 MPG... which is exactly what it is EPA rated for 19-32MPG (city/hwy)

Thanks for clarification. I'm not sure what my vehicle gets under 60 MPH & that could be the difference here. My motor really loafs along under 62 MPH.

FYI, a 2900lb 4 cyl Neon econobox is rated 32 MPG highway. Your 4300lb 3.8L van is rated 25 MPG. I'm not doubting you got 30 MPG once or twice, but I'm betting that's not your running average for highway use. That's a good bit higher than folks who own Intrepids.

[windsorboy]

Ah, I forgot... our gallons are different from yankee gallons (larger) and therefore mileage is much greater simply because we get more miles per Canadian gallon since it is larger. That's why... my window sticker lists EPA mileage at 31 or 32HWY (I forget) but it must be listed in Canadian gallons.... and that is what I do get consistently.

[Lscman]

Thanks, friend.

Seems we're talking a different language. I forgot a gallon was not always a gallon.

[gas28man]

I have a 1996 Town & Country with the 3.8 L.

With everything in working order, I consistently got highway mileage in the 24-26 range. Whenever it dipped below 22, I could be assured there was something wrong. It now has 256K miles on it, and it's getting down around 23-24 on the highway, and about 20-21 in combined city-highway driving, 18-19 in the city. I suspect my master cylinder is finally on its way out (at 256K, it oughta be), so there may be some drag in the brakes affecting the current results.

In answer to your question, I'd definitely look for something wrong, like a bad EGR valve, vacuum leak, dirty filters, or a bad sensor of one sort or other. Maybe even something simple like a loose or faulty spark plug wire. Do you know how to read the trouble codes, by turning the ignition key on-off-on-off-on? Do a Google search for "Chrysler Trouble Codes" and you should find a number of sites that tell you how to read the codes and what they indicate. You need no tools or code readers. Your Check Engine light on your dash will flash out the codes. This may give you a preliminary idea of what's up. With a 3.3 in an empty Grand Caravan, you should definitely be getting the 23-25 you expect on the highway.

Write back and let us know what you find.

[Lscman]

Thanks, gas...for the gas figures.

I just bought this thing, but it seems to run & idle smooth as glass with no engine knock. That would rule out a bad EGR.

The van has 55K miles on it, so maybe it is running rich due to a dirty, clogged air filter. I haven't had time to check it. Another possible problem is the O2 sensor. Maybe it got a tank of bad gas at some point & it's running rich due to sensor out of calibration. They will usually not throw a trouble code. As I mentioned, the van has no check engine light or other symptoms indicating trouble.

[Lscman]

Well.........

Just got back from 1000 mi trip with fresh air filter element and new OEM-spec spark plugs.

Highway mileage at approx 65-70 MPH remains at 20 MPG (USA gallon).

This engine runs smooth and never misfires, but I perceive a very slight, intermittent power-surging at near-steady cruise throttle positions that may imply poor A/F ratio. It is noticeable at various throttle positions & engine temps, even at full operating temps. Based upon past experiences on other vehicles, I'd interpret this surging to be a marginally-lean condition. The vehicle does not hesitate though, when throttle is pushed down. I see that Dodge reprogrammed my CPU memory in this 2001 van sometime in 2002.

Has anyone had an Oxygen sensor or MAP (manifold pressure) sensor go out of calibration on these 3.3 or 3.8 engines?? I notice there is no mass air flow, so I'm assuming these 3.3 & 3.8L motors use "Speed Density" fuel delivery control. In closed loop mode, the O2 sensor(s) would surely affect gas mileage. Does this vehicle have multiple oxygen sensors?

I wonder if Chrysler revised anything significant in later 3.3L production. Would a 2004 engine computer work in a 2001 for troubleshooting purposes?

Again, the van is not throwing any codes or intermittent engine lights.

Any repair info or experts here?? Thanks

[majj]

I have an 2002 with the same problem. I took it in for multiple checks and talked to dealers, mechanics, drivers, etc. I have been told that this is one of the cases when the smaller V6 may actually result in worse gas mileage. I didn't really believe it, but after repeated inquiries, it seems to be true. (Let me know if you find anything different)

I also ran into a friend who's in-laws have an 01' with a 3.8 and an 02' with the 3.3 and that was the first thing they noticed when they got the second one new. They also had it in for multiple check and have never come up with anything wrong.

The reason I found this group is because I am trying to find out if there are any modification kits out there to boost the power a little bit. I have been told to look into putting a K&N air filter on and seeing if there are any fuel injection modifications, computer upgrades, or fuel body spacers that can be used with this engine........

Let me find out anything different. I really want to improve our mileage too...

[gas28man]

Interesting observations. It sounds like we've covered all the bases.

In 261K miles on my 96 T&C with 3.8, I'm still on my original O2 sensor, and never had a lick of trouble from the MAP sensor, and am still getting 22-24 Hwy and 18-19 in town. I've been through 2 EGRs, however, and when those went out, mileage dipped by 10-15 percent. These mileage figures, of course, are taken from the on-board computer, but I have no reason to doubt the accuracy.

Just for grins, you may want to try an old racer's trick. Get a can of WD-40 and stick the little red tube in the nozzle. With the engine running, spray the WD around any spots where you think there might be air leaks, such as around gaskets, around vacuum lines, etc. If the engine surges when you spray, then you've found your leak. Still, this wouldn't necessarily resolve a mileage issue, but rather a loss of power -- although the two are often linked.

Have you looked into transaxle gear ratios of the 3.3-equipped models vs. those with 3.8s? This is about the only stone we've left unturned here, without getting into engine mods.

Rick