Upping economy in a 3.0 Litre 2000 Dodge Caravan (Van now retired)
 

UPDATE, 30-August-2014 - I've decided to retire this van from fuel economy logs. I saw a fuel leak under the van. I will say that the highest I saw this go on a single tank was 28.54 and that was mostly on one trip, mostly HWY miles.

This thread is about modifying my Father's 3.0 Litre, 4 SPD Auto Transmission Dodge Caravan.

Current Deletions:

A/C Belt Removed
A/C Clutch Fuse
A/C Clutch Relay (From the fuse box)
Bug Deflector
Handles from backs of Driver and Passenger Seats
Roof Rack
Seats; Middle and Rear

(About 200 pounds removed between floor mats and seats)

Current mods:

Plastic Stretch Wrap on Hubcaps
ScanGauge II
Rear Side Skirts, Partial, Duck tape
Weather stripping in some gaps

General maintenance:

Air Filter Changed - 2013-May-7, 8, or 9
Fuel Injectors Cleaned - 2013-September-06 (This didn't seem to make much of an improvement compared to how it was)
Oil Change with 5w20 Full Synthetic Oil (2013-March-23; However, We added 10w40 non-synthetic in late August as we ran out of Full Synthetic)
Spark Plugs Changed - 2013-May-13

Things checked at fill-ups;

Fluids
Tire Pressure - 46 for Winter, A bit higher for warmer months (50, Maybe)

Other info:

14 Inch Tires

Things I'd like to do to the van:

A/C Clutch Removal (It's not hooked up anyway)
Seafoam + Oil Change (At the 135k Mark or later; As of this edit we just broke 132k on 2013-11-21)
"Street Sweeper" Aerodynamic Strips on Sides of Van
Windshield Wipers Deflector

Driving is shared in this vehicle; My Father and I both drive it.

Money saved target; $320 - At $203.5x so far

Austin

I'd estimate that anything over 25 mpg in "moon" is a good accomplishment. Nice work on the mods done!

Um, have you adjusted the ScanGauge at fillup time to get its gallonsreadout to match the pump display? :)

I had a '92 with the 2.6 and 3spd, it never did better than 27 on its very best day. That was a long trip on the Interstate with a brand-new cruise control.

Of course, it puked up its ECC on that trip, but that's beside the point.

Getting over 25 is really good. I'm fascinated to see if it keeps it up, especially if you go deeper into the tank.

Are you sure it's a 3 liter? I didn't think the mitsubishi 3 liter was available that late. I would think it was the 3.3?

Yes, It's a 3-Litre (See link Fuel Economy of the 2000 Dodge Caravan/Grand Caravan 2WD) and the ScanGauge was adjusted at the last fill up (EDIT: But did I do it properly?) Almost 6 gallons have been used so far. The van tends to get better economy if at a lower elevation; We're located rather high. (EDIT: Is that true?)

Also, The rear passenger seats were removed and the AC belt isn't connected.

Edit: The engine says it's a Chrysler.

EDIT: I'm wondering if it's true that the van gets better economy at a lower elevation and it's not just the fact that it's on a 100+ mile trip.

Big car, lots of place for stuff that you (really) don't (really) need ...
I take it you've already thrown all the excess weight out - along with the rear seats ? ;)


I once rented a Grand Caravan / diesel version - thirsty b@$t@rd that was.
Thankfully, there were 6 of us to spread the fuel costs.

Not sure how much of an air dam you can get away with in the snowy months, but that's another option. Filling up the (enormous) wheel well gaps couldn't hurt. Coroplast belly pans... lots of stuff can be done, it just depends how self concious you are. :)

Yes, The rear passenger seats were removed. A few things are carried around in the car but it's far from being a tool shed or Hoardasaurous Mobile.

I don't expect to be going far out with mods to this vehicle now. If/when I get a Geo Metro, I can do much more than I'm doing with this van. Also, Not much city driving is done in this van due to our location.

(Edit, 2013-September-18: I don't think I'm about to buy a Metro.)

(Earlier Edit: The below parts I now take with a grain of salt due to the fact I did such little coasting and not much distance in the tests.)

I tried to A-B-A the tire pressure between 50 and 55 PSI to find the most fuel-efficient pressure and I somewhat flunked it. At first I was going to use 50 PSI (Roughly) As A runs and 55 PSI as a B run but I'll have to reverse them. A third A run hasn't been made. The pizza pans were on for all these tests which is partially why there isn't another proper run at 50 PSI; They take time to take off and on.

Averages and totals for "B" Runs, (Roughly 50 PSI) Counting going from home to the gas station:

35.95 MPG AVG
0.10 Gal
188 FWT Max
3.8 Miles
1754 RPM Max
42 MPH Max
24.5 MPH AVG
$0.40 Cost

Averages and totals for "A" Runs, (Roughly 55 PSI) Counting going to the gas station (Again)

32.03 MPG AVG
0.15 Gal
188 FWT Max
5 Miles
1898 RPM Max
42 MPH Max
21.6 MPH AVG
$0.69 Cost

I did drive more for the "A" Runs but I think these are still somewhat valid, Especially when comparing my first ride from home to the gas station compared to my second run which was fairly close:

First Drive, at 50 PSI:

40.5 MPG AVG
0.06 GAL
186 FWT Max
2.4 Miles
1754 RPM Max
42 MPH Max
26 MPH AVG
$0.23 Cost

Second Drive, at 55 PSI:

38.9 MPG AVG
0.06 Gal
184 FWT Max
2.4 Miles
1898 RPM Max
42 MPH Max
24 MPH AVG
$0.24 Cost

I didn't deflate the tires from 55 back to 50ish today.

Also, I must note that I use hills (Down Slopes) for acceleration when and where possible.

Austin

That's weird - - - I'm a bit surprised you seem to be getting better mileage at 50 than 55psi in the tires. I wouldn't have guessed that.
:confused:

Lose the bug deflector on the hood. Easy mod, and good for another 0.296 MPG, guaranteed! ;)

There's probably a flush, transparent tape substitute, to guard against stone chipping.

I'd like to take that off but it'll stay for now. I put the battery on a trickle charger for now and hopefully we'll have an oil change soon.

A full synthetic oil change and a new oil filter were had today. However, The van feels different now; My MPG doesn't seem to be quite on par compared to how it was before, Especially considering this thread with the aerodynamic drag I had:

http://ecomodder.com/forum/showthrea...0-a-24779.html

I didn't go on the same trip today but I went on a similar one. I think that pulse and gliding doesn't work or I'm exceeding the best engine load, I didn't turn the engine off for this though. Also, The tires are over-inflated; I must find the most efficient tire pressure.

EDIT, 2013-September-18: I wasn't used to how the van felt after the oil was changed.

So, if the A/C belt is off, why don't you also take all its hardware away? An A/C compressor, condenser, evaporator and other stuff is quite heavy...

It hadn't occurred to me to do that, I'll ask my Father about it. We don't actually know if the A/C works. Thanks.

If you ever do that, it would be better you make sure any remaining cooling gas (in the case it might be the R-134a) to be drained and recovered instead of just thrown away at the atmosphere, since it's a "greenhouse gas". Ironic, isn't it?


Often, an A/C doesn't work due to the absence of the cooling gas :D

Another likely reason is the compressor or its clutch. A belt and a $300 clutch are a lot more spendy than opening your window. Lots of folks'll just cut the old belt off and move on.

I set the tire at 45 PSI and the van accelerates quicker than at 50 or 55 PSI.

Edit: I don't think the MPG numbers I was reporting were accurate, I don't believe this Scangauge II was set up very accurately.

(Edited again, 2013-September-18)

Another edit: I wonder if it still accelerates faster at a lower pressure?

The bug deflector was removed. The ScanGauge has been calibrated a bit, The Speed setting was upped by 2% over stock settings so far but it may require even more to be accurate with the stock Trip meter. The ScanGauge speedometer must be fairly close with the trip Speedometer prior to adjusting the Tank settings, Right?

It also seems as if heavy-load low-gear acceleration pulse and gliding from 45 to 65 and back to the Drive gear doesn't work very well in this van or if it does there's not much of an improvement over other methods I've tried plus it maims my judgment of other drivers and when I should pull out from streets to roads (Which may cause tailgaters to be behind me) and other things; I'd also rather not damage the transmission too much.

EDIT, 2013-September-18: If I am to glide more I need more glide time. Also, Changing the Speed setting distorted the SG2's estimated Miles Traveled and the van's on-board Speedometer reads a bit high.

I must report failure; My previous high MPG numbers were false readings. I'm still calibrating the ScanGauge II but at the moment the current MPG is at about 25, According to the pump and stock Trip meter even with discrepancies at the last fillup though even that may be a little optimistic. I wonder how high the FC was prior to removing the tire on the roof.

I still believe I can get over 35 in this van, Though. I only need to keep going.

Edit, 2013-September-18: I didn't understand the SG2 instruction manual very well prior to "Calibrating" the SG2 in my earlier days. We also didn't have complete fill ups often when I originally posted this reply.

After a long trip, The economy was at about 37.8 according to the SGII. (It's probably closer to 30.) Pulse and gliding was experimented with again and it appears to work when done properly; Not at WOT but at a IGN rating close to what would be if the accelerater wasn't pressed; Pulsing for three seconds then gliding for nine.

Is this an appropriate place to post this?

The duct tape grille block was removed on the return trip as the fWT was almost up to 210 at a red light.

Edit/Update: When I was trying to pulse and glide as I described here, I hadn't watched videos on the subject; I did it in trial-and-error prior to this.

We had the air filter and spark plugs changed. I also put more air in the tires. I think that will be it for modding the van for a while, Unless I can find something cheap to do.

And I only recently with this last fillup started to adjust the ScanGauge at fairly properly; Until recently, I'd only zeroed the tank for a baseline though I thought it was higher when I started this thread.

For some reason, The SGII is reading wonky when I check the tank info - It says we went through over 1,200 gallons, Got 2.7 MPG or so and that the water temperature is under 40 below. Why is it doing that?

There's not much to talk about today but the van had some low economy last month due to going to a small local station that apparently sold us some dirty gasoline. The SGII because it's gone wonky as of late too so I don't know what FE we've gotten in the van lately.

EDIT: That wasn't appropriate grammar, Was it? "The SGII because it's gone wonky as of late too so I don't know what FE we've gotten in the van lately."

I kinda text searched your thread and saw no mention of a "Grille block"... It seems to me that many people have seen mpg economy improvememtns from simply adding a grille block. Give it a shot and let us know what mpg gains you see.

Thanks

I'm not about to put a grille block on the van right now, But Thanks. I did have a full one on the van a while back in the winter and it was all duct tape. I have to mention though, I was warned that these vans can overheat rather quickly and considering the (Poorly maintained) 1997 Plymouth Voyager I drove prior to this van had paint coming off the hood from overheating, I'll need to be careful. But the ScanGauge II does have the FWT meter which I can use.

BTW, The fuel economy seems to have gone up lately compared to how it was in June and July since we've been buying gas from larger chain gas stations. For those who might not know at the time reading this reply, Back Months ago we bought gas from a small local station and it was like burning a rope that was watered down - The meter said we were getting about 16 MPG at one time which is probably the lowest I've seen it read, I might be getting higher FE than that in the Caprice.

I still need to reset the ScanGauge II.

Earlier Edit, 2013-August-31 - Reason for editing: I added "Read" to "probably the lowest I've seen it," to make more sense

Edit, 2013-September-18: It wasn't actually a completely full grille block, It was on the higher two vents but the lower ones were still open. Also, I do feel like adding a partial grille block.

The fuel injectors were cleaned today. Initial thoughts are that the van accelerated faster but it might have slowed down faster too? Am I imagining it? Perhaps; The Walmart employees put the tires at 35 PSI so I had to set it back up to 46 hot.

Also, My theory of getting higher fuel economy at a higher tank doesn't seem to hold true given the latest fuel log.

Father and I put stretch-wrap over the hubcaps the other day. After testing it initially, Plastic was falling out so we taped it in. Although the plastic wrap is more prone to holes it's not going to rust like a pizza pan nor is it going to fall off just like the two front pizza pans did.

Edit, 2013-September-18: I much prefer the plastic smooth covers at this time.

As of 2013-09-14, It would be good to write down some trips as according to Google Maps, To see if the odometer works properly at this tire pressure.

Also, Perhaps with the weather changing a small grille block of duct tape will be added along with a block heater or water temperature heater.

I reset the SG2 prior to today's fill up (Which read 25.1 MPG with 200+ miles on one trip this September 13th) then it was still acting up at the fill up time and I set the tire pressure to 50ish today.

Here's a photo of the plastic wrap on a hubcap:

http://i50.photobucket.com/albums/f3...psfd3b9af6.jpg

I put a duck tape partial grille block on along with partial rear side skirts made out of tape.

Original post edited.

I had a 1998 3.0 liter Dodge Caravan. Just before I sold it I took a 2000 mile R/T from Houston TX to Iowa pheasant hunting. The Caravan had 280,000 miles on the odometer. I consistently drove between 60-65 and averaged 26mpg. I estimated my mpg by dividing miles driven by gallons purchased, I don’t have a ScanGauge. I’d pulled out the back seats so I could sleep in it, but still carried the weight of my camping and hunting gear as well as my 75lb golden retriever. If memory serves me correctly, I inflated my tires to 45psi. All things considered, I was very pleased with the 26mpg I was getting. The 3.0 liter engine was an excellent engine, gave me no non-maintenance problems, and was still running great when I sold the Caravan at 286,000 miles (wish I could say the same for the AC and AT LOL).
Steve

The van seems to be going through coolant faster than we'd like so I removed the duct-tape grille block. I might add it again in winter conditions, When it can make more of a difference. We also need to replace brake pads.

Also, Since I reset the SGII to factory defaults I haven't had any wonky tank readings but we also haven't filled the tank up since 2013-September-17 yet.

If your losing coolant I'd say you have a leak somewhere, your engine has a long hidden metal tube that runs under the intake manifold to the water pump (that's buried in among the cam pulley's), perhaps it's leaking from there when the system pressures up and then stops leaking when you let it cool down. If your running it hot I'd be very very careful, aluminum heads are not very forgiving when they're overheated. They tend to warp and also develop cracks between the sparkplug hole and the exhaust valve. Like I told my late wife and kids, if you're overheating pull over as soon as it's safe and either call me or call a tow truck and tow it home.

Anyhow, good luck with it.

Steve

Or it's the elbow pipe back to the water pump. Or it's the supply and return to the rear heater... Lots of places to loose coolant in those rigs.

Whatever the case, We have a "Stop Leak" Additive we might be putting in the van soon prior to filling it up with more coolant.

The SGII was bugging out again at re-fill time; It said some high figure like 1700-1800 gallons used.

Be careful about using too much stop leak, it can clog up your cars heater and even effect the radiators cooling capacity (a hard lesson learned). I have had good luck with it though, I even used it to temporarily (for 60,000 miles) fix a cracked head (the exhaust valve seat to spark plug hole crack I mentioned earlier). However, when I finally had to replace the spark plugs the crack opened up again and I couldn't get it to stop leaking after that.
Steve

Thanks, I didn't add the stop leak but my father did.

There's not much to add now except I found 55 MPH might actually be less efficient on highways than a higher speed in this van? Constant throttle at 55 had lower instant MPG readings than at 63-65, At a TPS between 16-25; 16 is the zero (Not holding down the throttle) point.

Going up some long hills, I think I should stay at 45 instead of 35 (While keeping speed limits in mind as they might decrease) and keep the Instant MPG reading above 10 even though the gauge isn't calibrated; On some smaller inclines I can lose 5 MPH and regain it on the way down. And I have to keep the traffic in mind when doing this. Why is it that so many times I've seen many people tailgate me or be so close to it?

Oh and if I were to take the A/C Clutch Relay out of the fuse box, Would that help economy at all? I also noticed I can make a switch for a fuel injector fuse cutoff switch, And would like to do that.

Instant MPG readings aren't the best way to measure consumption at a given speed - they're notoriously fickle.

Better to drive a stretch of road in both directions, and reset/read the average consumption meter at the same points, at the same speed. Average the results.

I'm willing to bet you a donut your van gets its best economy just after the torque converter locks, like practically every other vehicle out there ( http://ecomodder.com/forum/showthrea...you-15182.html ). Anything beyond that is downhill.

Actually, in some vans and trucks, it's possible you may get best economy just after the top gear engages, but before the lockup point, owing to lower road speed (lower aero drag).

It might save a little bit, if your A/C comes on automatically (as most do) when you turn on the defrost setting on your climate control.

I'm wondering where to test the van to see what fuel economy we get from it at given, Constant speeds with the cruise control on; I could go on I-80 but there aren't many flat long stretches of road that I know about within fifteen miles of the house I'm living in as of this post date; Perhaps the best thing to do is just test on I-80, I can still gently pulse to 65 on a down slope and then glide down to 55 on up slopes after the test.

I did say that I got more FE at 55 than 65 before, But would like to repeat it now that the SG2 is working better and I'd like to test it differently.

I also timed the water temperature heat-up time (While driving it) And it took between seven and eleven minutes and about 3.3 miles to get to 175-185 Ferenheit, At about 73 degrees Farenheit. Hopefully we'll get a water heater some time, Not only for winter.

Will the defrost still work if I take the clutch relay out? (Maybe I should find out for myself.) The A/C belt is not in the van and I tried using the system with the relay out, It still blew air but I didn't try the defroster.

defrost
 

Defrost: you'll still get heat blowing on the windshield, but you won't have the dehumidifying effect of the AC. So it'll defrost like any old car without AC used to work.