Noob questions about pulse and glide

[puddleglum]

Thanks, sounds like I just need to master the techniques and not worry so much. I don't mind working the clutch as long as it doesn't cost me money. I've actually been enjoying driving again for the first time in a long time. I do have a SG and I watch it closely. I've been mostly doing what you said already so maybe just need to keep practicing. I have a full grill block, insulated belly pan, hood and around a good portion of the engine bay. It's just with a 4 mile commute and a third to half of that in neutral, it doesn't run long enough. Do you shut the engine off when you're stuck inching along in traffic?

[Fat Charlie]

It depends on just how stuck things are.

[California98Civic]

In stop/go, crawling traffic, I will bump start as low as 20 mph. And anywhere that I sit still for at least 7 to 10 seconds, I will shut down and use the starter when it's time to move. I slow-moving traffic, I do like trucks and let a little extra space open up in front of me. I roll along slowly at 25 or 35 MPH pluse and gliding. Regularly see some of my most amazing FE numbers in the worst LA traffic.

But until you are much more comfortable with bump starting I would recommend not trying it below 20 mph or 3 rd gear much. It is harder to do gently at really slow speeds.

[Magician]

I EOC a fair amount and I even bump start under 10mph sometimes... The little Civic VX engine doesn't mind a bit.
My Other Car is a 2000 Civic EX... I swapped out the engine for a JDM B16A that I actually get better MPG's (35mpg)than the stock engine... and have much more power if I so choose to use it. I don't drive it much as my VX is my favorite car of all time.

[Lemmy]

Forgive me being a bid radical, but isn't a puny four mile commute a bit of a waste of fuel? why not just cycle it? I got an 8 mile commute and cycle it in about 27 minute, only 7 or so minutes than I can manage it in the car.

[Magician]

Yes... 4 miles is a short commute, but my commute is only about 6 miles, but not very bike friendly and not worth the risk of injury, but this is slowly changing around the Omaha Metro Area. With my 50+mpg's.. I can drive to work all week on just barely over 1 gallon of gas. At $2.19 a gallon in the central part of the U.S.... not a huge concern. Even when our gas was almost double... still not a big deal with the economy I'm enjoying. It's fun driving one of the most fuel efficient vehicles ever made.

[ECONORAM]

Originally Posted by Mr. Pancake

If you have to slow down it is best to slow in neutral. The trick is to throw it into neutral early enough that you will be down to the target speed at the right time.

For example: if you know the speed limit decreases ahead find the spot where you can coast in neutral from and reach the slower speed zone at the reduced speed limit. This way you are throwing away less of the energy that was used to get up to speed in the first place.

Neutral, DFCO, brakes {last resort }

If your vehicle is like my pickup, even when you put the trans in neutral while moving, the engine rpms do not drop below what they were with just the throttle lifted while in gear. --> due to the engine management system.
Even with that, I have seen pulse and glide work, just not as well as my wife's car, which goes into DFCO if you lift off the throttle at speeds above 60mph.
Based on what I have learned from driving the wife's car, I am ordering parts to fabricate for my truck a cockpit and/or throttle activated fuel cutoff. This may be of interest to the OP, if the vehicle is injected.

[ECONORAM]

Originally Posted by Ecky

Here's a BSFC chart for my engine:




I generally drive at 50mph when the speed limit is 50 or above, which puts me right at 2000RPM, where the engine can most efficiently convert fuel into motive energy. From the chart, you can see that above ~75% load, efficiency begins to drop off, so it's best to accelerate at high but not full load.

I have a $3 eBay ELM327 bluetooth dongle paired with my smartphone I used to keep an eye on load until I got a feel for it.

So where, or how did you get this chart for your engine? I'd like to get one for my truck.
And, for those like me, who really didn't/don't understand the whole pulse and glide concept, take a look here at this autospeed page: AutoSpeed - FuelSmart, Part 1

[California98Civic]

I confess, I have always found BSFC maps labelled like this one a little confusing. The vertical axis is labelled "engine torque" but we are discussing it as if it is "load percentage." The below image from Autospeed article ECONORAM linked in post #28 above has a map labelled "engine load" on the vertical axis. Torque and load % are not the same thing, though. And on Autospeed graph it seems like 45% to 65% load would yield the best FE.

[puddleglum]

Originally Posted by Lemmy

Forgive me being a bid radical, but isn't a puny four mile commute a bit of a waste of fuel? why not just cycle it? I got an 8 mile commute and cycle it in about 27 minute, only 7 or so minutes than I can manage it in the car.

I missed this comment, didn't see it till now. Since it was about my commute I'll still respond. If I lived in a warm climate with less drastic swings between daylight and dark I probably would bike year round. I know guys that do it here, but my old body just won't take it anymore. Not to mention, to ride a bike in the dark on slippery streets in heavy traffic you have to have a death wish. I rode my bike most of last summer. I loved it and really hope to be back on it soon, maybe this week. I don't know if this guy would be so happy to be out riding if it was in the dark with 30-50 kph wind and wind chills in the -30's C. It's still been freezing nearly every night here.

Anyway, enough of that. I think my skills are improving. Set a new personal best for myself this tank so I'm happy. I think this car really is at its best in city driving. Thanks again guys for the advice, it's helped a lot.