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-   -   Pulse and glide with Caravan automatic (actually EOC) (https://ecomodder.com/forum/showthread.php/pulse-glide-caravan-automatic-actually-eoc-374.html)

popimp 12-21-2007 04:34 PM

Pulse and glide with Caravan automatic (actually EOC)
 
I've been wanting to try Pulse and Glide with the van. Actually turning it off and coasting. I tried coasting in Neutral with the engine on but I don't think that it actually works at highway speeds.

My manual says

TOWING A DISABLED VEHICLE
With Ignition Key
Your vehicle may be towed under the following conditions:
The gear selector must be in NEUTRAL, the
distance to be traveled must not exceed 100 miles (160
km), and the towing speed must not exceed 44 mph (72
km/h). Exceeding these towing limits may cause a transmission
geartrain failure. If the transmission is not operative,
or if the vehicle is to be towed more than 100
miles (160 km), the vehicle must be towed with the front
wheels off the ground.

Damage to the transmission may occur if the following
precautions are not observed:
• Shift into PARK only after the vehicle has come to
a complete stop.
• Shift into or out of REVERSE only after the
vehicle has come to a complete stop and the
engine is at idle speed.
• Do not shift from REVERSE, PARK, or NEUTRAL
into any forward gear when the engine is above
idle speed.
• Before shifting into any gear, make sure your foot
is firmly on the brake pedal.

brucepick 12-21-2007 08:14 PM

Well, if your foot has to be firmly on the bake pedal - I think that means no P&G. At leaset not with the engine off.

I've been doing what P&G I can with engine idling in neutral. My owners manual lets me shut down if coasting up to 40 mph but I usually don't like to do it. Gotta use the battery to restart, headlights blink out to upset other drivers, etc. etc.

I don't have a ScanGauge or SuperMID so I can't prove that coasting with engine idling saves fuel, but I think it does. But obviously not as much as if you can shut it off!

I'm pretty sure my next car will have a standard tranny. Thing is, Volvos last approximately forever so it may be quite a while.

newtonsfirstlaw 12-21-2007 08:43 PM

I'd say P&G for this in Neutral is not an option.

MetroMPG 12-21-2007 08:52 PM

I'd say P&G for this vehicle at highway speeds isn't worthwhile anyway. Just a hunch, but I bet the transmission losses under accel (and the inability to control for load) combined with the aero losses during the coast at higher speeds would make it an awful lot of work for little or no gain and arguably more wear. I could be wrong - haven't tried it with the SG in this type of vehicle.

Lower speed engine off coasting is another issue. I've done some in my brother's Chrysler minivan (same as yours, but not sure if his V6 is the same displacement as yours) - approaching stop signs, that kind of thing. You probably already know the steering is MASSIVELY heavy on the van without assist. Brakes are A-OK for one or 2 reserve-assisted applications, of course.

Also, you probably already know you can get to neutral with a palm-forward "push" of the lever, right? (Pushing away and slightly up.) No need to pull the lever to get to N. The "push" movement minimizes the risk of selecting R or P by accident.

RH77 12-21-2007 08:58 PM

Minivan Dynamics
 
Quote:

Originally Posted by newtonsfirstlaw (Post 2791)
I'd say P&G for this in Neutral is not an option.

Well, this is up to interpretation. "Firmly on the brake pedal" translates to a safety issue -- we don't want the generally public choosing a gear without being ready!

Perhaps a "mild" P&G scenario can develop. My car has the same limitations in the manual, but I've engine-off coasted for over a year, at speeds up to 70 mph. Knock on wood -- no problems after ~20K miles (130K total miles).

I've EOC'd in late-model Caravans and found that they don't like initial D-to-N shift, and after startup, the shift back into D (including an attempt to rev-match). It feels like a harsh engagement. The steering is VERY stiff too -- as I'm sure you may have noticed.

An decent increase in FE can be attained with engine-on coasting. P&G is up to interpretation/testing in this case...

RH77

popimp 12-21-2007 09:49 PM

I think that as long as the speed is less than 44MPH than it shouldn't be a problem. My question is how long is the 100 miles. Would the 100 miles reset after you started to drive again or is the 100 miles for the life of the vehicle? I tried P&G with engine off today and set the SG2 in Hybrid mode. I think I'll keep it up in the city and avoid it on the highway.

popimp 12-21-2007 09:52 PM

The P&G with engine on does not work at high speeds. I verified this on my way from Mississippi to California. Although the SG2 reported about 30mpg I only got about 26. As far as engine off goes I'm not gonna try it on the highway only in the city.

popimp 12-21-2007 09:53 PM

Quote:

Originally Posted by MetroMPG (Post 2792)
I'd say P&G for this vehicle at highway speeds isn't worthwhile anyway. Just a hunch, but I bet the transmission losses under accel (and the inability to control for load) combined with the aero losses during the coast at higher speeds would make it an awful lot of work for little or no gain and arguably more wear. I could be wrong - haven't tried it with the SG in this type of vehicle.

Engine off coasting is another issue. I've done some in my brother's Chrysler minivan (same as yours, but not sure if his V6 is the same displacement as yours) - approaching stop signs, that kind of thing. You probably already know the steering is MASSIVELY heavy on the van without assist. Brakes are A-OK for one or 2 reserve-assisted applications, of course.

Also, you probably already know you can get to neutral with a palm-forward "push" of the lever, right? (Pushing away and slightly up.) No need to pull the lever to get to N. The "push" movement minimizes the risk of selecting R or P by accident.

What kind of MPG did you get in your brothers van?

MetroMPG 12-21-2007 10:06 PM

I don't know - it wasn't SG equipped.

Make sure you won't be in any situations where you may need to steer quickly - I'd try it first (steering, engine off) away from traffic if you haven't already. You may change your mind.

Quote:

Originally Posted by popimp (Post 2814)
My question is how long is the 100 miles. Would the 100 miles reset after you started to drive again

I would say it resets. It's likely a lubrication issue -as soon as you start the engine, you're OK again. Oily bits re-oiled. (But don't sue me when it falls out the bottom of the van, OK? :))

popimp 12-21-2007 10:11 PM

The steering was diffictult. I won't use it during turns only on straight aways. So basically when I'm EOC it's like towing a disabled vehicle according to the manual right?

MetroMPG 12-21-2007 10:17 PM

That's what I would say, yup. And I agree with Rick - I think the "brake to shift" warning is a safety issue and not a technical one (except from P, but you're not doing that when EOCing).

popimp 12-21-2007 10:20 PM

It was kind of weird watching the SG2 display 9999 for my MPG when EOC. One more question then I'm done. Would it be better to wait until the engine is fully warm before doing EOC?

brucepick 12-21-2007 10:53 PM

I found my steering got a lot lighter when I went beyond 44 psi to about 50.

That lightness is what gave me the idea to remove the belt that runs the p/s as well as the a/c. I'm sure powerLESS steering would be tougher at 30 psi than at 50-52.

Though I suppose you already have your tires up where you want them...

RH77 12-22-2007 02:30 AM

Quote:

Originally Posted by popimp (Post 2826)
One more question then I'm done. Would it be better to wait until the engine is fully warm before doing EOC?

That's a good question. Many technique-oriented hypermilers use a kind-of "stepped-up" approach to warming up a vehicle: Pulse up to certain speed, shut down and coast, restart, pulse, coast, shutdown, repeat.

Since I have an automatic, especially with a cold-soak, I do this only when I have to stop for extended periods (traffic light, parking toll booth, etc.) I feel there is a lot of stress on the engine/transmission with fluctuating temps at cold start (especially below 30F) -- so it's kept to a minimum. It's a personal decision on how much wear you want to place on the starter, battery, and other components -- especially at cold startup.

Quote:

Originally Posted by brucepick (Post 2831)
I found my steering got a lot lighter when I went beyond 44 psi to about 50.

That lightness is what gave me the idea to remove the belt that runs the p/s as well as the a/c. I'm sure powerLESS steering would be tougher at 30 psi than at 50-52.

Though I suppose you already have your tires up where you want them...

I agree. At 50 psi, steering is much lighter in my application. But with the Chrysler-based minivan design, so much weight and pressure is placed on the front axle -- making it harder to steer. I've rented about 6 Chrysler minivan variants (Caravan, Grand Caravan, and Town/Country). 2.4L I-4, 3.3L, and 3.8L - V-6s. Mileage ranged from 18.5 mpg in the 3.8L mpg to ~22 in the 4-cyl (combined). I grew up driving an '88 Plymouth Voyager SE, 3.0L (Mistu) V-6. At 250K miles, the speedo/odo quit, but it kept going until 300k (?) before we sold it and I got my own car. The Plymouth was virtually indestructible. Good times :thumbup:

RH77

MetroMPG 12-26-2007 03:49 PM

Popimp: any updates on engine-off coasting the Caravan?

popimp 12-26-2007 04:21 PM

Yes I did it for a day but I haven't driven the van since then. To get the least amount of jerk I have to give the van a second or two before I take it from Nuetral to Drive after starting.

popimp 12-26-2007 08:37 PM

I filled up today and got 25.47 MPG. I drove on the highway from here to San Francisco with is about 50 miles one way. There was a bit of city driving while I was there. I'm not sure if EOC is working or not but I got better MPG compared to my last highway drive, although I won't rule out fill errors.

DifferentPointofView 12-27-2007 01:36 AM

I experience a surge in rpms when shifting to drive from neutral and also with the same bit of surge when shifting back to drive. Maybe a Chrysler thing? It says somewhere in the manual that it shifts automatically into neutral or the highest gear possible (I forget what my manual says) I'll only shift to neutral at stoplights now.

popimp 12-27-2007 03:03 AM

Are you shifting with the engine on or off?

DifferentPointofView 12-28-2007 09:50 PM

It's an auto tranny, and of course it's with the engine on, because to have RPM you have to have it on.

Who 12-29-2007 02:10 AM

I can't seem to get any success using P&G above lockup speed on the TC. It's most advantageous when in urban traffic where I can't go fast enough for the slushbox to shift into 5th.

It would be nice to have really controlled situations to check TC slippage (oh how I wish the ScanGauge could do RPM/MPH or KPH) and it's affect on mileage. I'm temporarily in Florida on vacation and it's really flat except bridges, so I am finally getting ideas of steady state speeds and also very controlled climbs. The one thing that has surprised me is that the best way to go over a bridge is to hit it really fast and bleed speed all the way to the top. Climbing at a steady 50 - 55 MPH is actually quite bad due to major slippage. So even though I try to go 52 or 55 MPH, I hit the big bridges at between 65 and 70. DSG or bust!!! ;)


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