How to accelerate in P&G mode?

[1993CivicVX]

Originally Posted by monroe74

This came up in another thread a few weeks ago. My VX pulls smoothly from 1000 rpm. Or even a bit less. Even in top gear, and even going up a moderate grade, and/or with one or more passengers. I think other VX owners have reported a similar experience. I think there might be something about your engine that is not providing proper power at low rpm. I realize you're still getting good results, but I think maybe you could do even better.

I think I suggested you check the timing. I don't recall if you mentioned doing that.

Yeah, I remember this. Maybe there is a discrepancy between our definitions of "smooth" but my car will not pull at 1000 rpm in 5th gear smoothly--it will do it--but I wouldn't characterize the mild vibration and unwillingness as smooth. 1250RPM in 5th gear and the car is very happy. I don't think there is anything wrong with the car--just an old engine (200,000+ miles --dunno how many exactly since the odometer only works about 60% of the time)

[monroe74]

Originally Posted by 1993CivicVX

my battery is often too low to start the engine using the ignition

I do a fair amount of EOC. I do tend to avoid it at night, because I'm a little concerned about the headlights draining the battery. Nevertheless, I think there might be something wrong with your charging system. Unless you're doing something extreme, I think you shouldn't often have this problem. I have a feeling maybe you need a new battery. Have you checked the level in it? It could also be something simple like a corroded connection.

Also, with a warm engine, the cranking required to start it should be very minimal. So this might be another clue that your engine isn't running quite right.

Slightly embarrassing to have to push the car in the middle of town and then jump in and bump start it.

Years ago I had a bunch of cars that worked this way. I would routinely look for parking spots that would let me roll downhill. But this was because they were old sports cars in poor condition. A few Fiat 124 Spyders, an Austin-Healey Sprite, an Austin-Healey 3000, and a TR-4. At one time or another, these cars had faulty charging/starting systems.

British car inside joke: Why do the British drink warm beer? Because Lucas makes their refrigerators. (Lucas is the company that makes electrical parts for British cars.)

Anyway, you have a Honda, not a Triumph, and I think you probably shouldn't be having this problem. Like someone said, you can solve the problem with an external charger, but I think that shouldn't be necessary, unless there is something extreme about the way you're using the car (e.g., I assume you don't have a 10,000 watt stereo).

I realize the VX has some special logic which restricts the way the alternator works, but I think you still shouldn't be having this charging/starting problem.

Originally Posted by 1993CivicVX

Maybe there is a discrepancy between our definitions of "smooth" but my car will not pull at 1000 rpm in 5th gear smoothly--it will do it--but I wouldn't characterize the mild vibration and unwillingness as smooth. 1250RPM in 5th gear and the car is very happy.

Yes, the word smooth is subjective. But when I say smooth, I mean really smooth. No vibration or unwillingness. Even down to around 800 or 900 rpm, although it's hard to tell just using the dash tach. This assumes fairly level ground, no passengers, warm engine.

Then again, 1250 is not radically greater than 1000, and the dash tach perhaps isn't a precision instrument, so maybe what you're observing and what I'm observing is not drastically different.

[Hateful]

I just go by sound;Automatic 4 speed BTW..... When accelerating I listen for the steady increase in RPMs and a nice smooth gear change, then the same repeated for the next gear.
When cruising at highway speed ( or my version there of) I listen for a certain up/down sound almost as if the transmission was slipping.Then shift to neutral when I feel I'm going fast enough for a good glide.

[R.I.D.E.]

Best mileage in my Del Sol was 47. Pale does much better in a heavier car with the same basic engine tranny combination (I think).

Aero drag in city EPA cycle is 29%, highway is 70%, so aero is always a factor.

70% throttle in low enough gear to have your revs peak at 2200, then shift to higher gear.

Draft if possible, it's easy here with fairly heavy traffic.

Instead of EOC (which you stated you don't use, like me) here is an option.

Whenever you need to slow down use the highest gear practical to keep engine revs above 1000 RPM. I used to never downshift to slow down, but now I think it is a big factor in my mileage improvement.

If you know your traffic light patterns, try to time it so you don't have to decelerate more than a coast, but if you find your self having to stop for a light, try to use downshifting to stop all fuel delivery, which is the same as shutting the engine off (no fuel delivery).

I find the ideal average for me is 1 to 3 pulse to glide, at about 40 MPH average speed. 2200 in your car should be about 52 MPH. Thats for a 1.5 engine (not SI) and manual tranny (which I assume you have).

At above 50 MPH average try to find a draft. Vehicles with larger frontal areas than yours are best. It may be better to just draft than to try to P&G at higher speeds, try both methods to see which works best for you in your situation.

The same applies to the CRV except drafting would be much more effective.

Drafting for me is 3 highway stripes between me and the host vehicle on the Interstate at 65 MPH (about 125 feet). Lower speeds would be closer. At 45 MPH around here if you give the car in front of you more than 6 lengths, someone will always pull over in front of you and then slam on the brakes and turn right. I try to keep my minimum stopping distance between the host vehicle and my car. Closer may be more effective but it also becomes a lot more dangerous.

Every suggestion should be considered and adjusted to your specific desires and the traffic you have to deal with. I have driven 64 east from Richmond at 77 MPH, in bumper to bumper traffic with less than 5 cars lengths between any vehicle, for 60 miles, without anyone moving more than 200 yards ahead or behind anyone else. Thats pretty much the saturation point for a 2 lane (each way) Interstate at 65 MPH.

regards
gary

[sonyhome]

Hmmm... I'm not quite sure I follow.

From a stop, 1st quick to 2nd, up to 2000RPM, 3rd to 2000RPM, 4th to 2000RPM, coast.

That would be better than 1st/2nd/3rd then coast (higher RPMs), or 1st/2nd then coast (even higher RPMs)?

Would it help to take a counter videos while P&G'ding, with different scenarios to have experienced P&G'ers tell which looks and sounds liek the best P&G?


I usually P&G from 35 to 45, and I play the lights. If it turns orange and I'm close, accelerate, if I'm far, coast or even brake to get green before I have to stop.

I don't draft in city traffic because people's driving is erratic. I find P&G more effective, as I can coast 3-to-1 like said above, my commute is flat or slight inclines perfect for P&G with a low roll resistance car.

[sonyhome]

For the fuel rate monitor, photos would be good, not just the taping of the injector, but overall what was done, the tapped wire needs to go back to the cabin.

Also the tap gives you:
-duty cycle
- engine RPMs

But you're missing speed to get MPG.

Therefore it'd be nice to tap another signal to get speed or tire rotations.

With that, we could do a cool ultra precise hypermiling analyzer.

[palemelanesian]

There are two different things going on here: accelerating, and cruising. For accelerating, use light throttle. For P&G where you would otherwise be cruising, use heavy throttle.

For accelerating, use first gear just to get moving. Go into 2nd gear at < 5mph, and from there use very light throttle up to a max of 2000 rpm before shifting, and keep shifting early as you gain speed. Use this to get up to, or nearly up to, your cruising speed.

Once you get up to speed, then start cycling between heavy throttle and neutral coasting - pulse and glide.

[sonyhome]

[Off topic fuel meter]

Thanks! With that long a wire you still don't disrupt the ignition? Great, simple...

You do have RPMs with that tap, just not measured by your voltmeter. On a PC you'd see the frequency of the pulses, and the duration of on vs off (your duty cycle).

With VSS you have your speed.

With some software smarts, you have your knowledge of when you shift gears or coast...

That is definitively a project I'll want to do, including the software part.

I think using the audio input channel is the easiest. Can be done for injectors, but what about VSS? What kind of signal is it going to be? Gotta look around.

[theholycow]

Should we take this over to the fuel meter thread?

Originally Posted by sonyhome

[Off topic fuel meter]

Thanks! With that long a wire you still don't disrupt the ignition? Great, simple...

The wire isn't connected to the ignition, it's connected to the fuel injector. Anyway, I too was concerned about disrupting the fuel injector, but my FE keeps going up and I'm not throwing any codes, so I it seems to have no ill effect.

You do have RPMs with that tap, just not measured by your voltmeter. On a PC you'd see the frequency of the pulses, and the duration of on vs off (your duty cycle).

Careful with terminology. It's a dwell meter as used here. While you could get RPM data from it, why go to so much effort and do it the hard way when you can just get RPM the old fashioned way from the tachometer wire? Even easier if you're using a PC, use a $30 (on eBay) ELM327.

It probably won't work with your '93 Del Sol, though, unless that car is OBDII.

With VSS you have your speed.

You'll get that with the ELM327 too. Since it's so cheap, that probably ought to be your starting point. I'm pretty sure there's open source software for it so you can write your own piece without rewriting everything.

With some software smarts, you have your knowledge of when you shift gears or coast...

Again, th ELM327 will cover that too, with throttle position.

That is definitively a project I'll want to do, including the software part.

Whichever way you do it, I'd like to be involved a little. I can't really write code unless it's simple, and I can't help with hardware due to geographical differences (unless you happen to live in the RI/MA/CT area).

[sonyhome]

(OFF TOPIC)

Originally Posted by theholycow

Should we take this over to the fuel meter thread?

Sorry, phased out of existence

Why not?

The OBD2 stuff is out the window, I want OBD1 or plain wire taps for the DelSol. For the CRV & OBD2, I have the ScanGauge.

Couple of notes:

I'm really slow at projects like that.
- This WE I stayed home, and got around to fix my CRV speakers
- ...and cut foam grill blockers for the CRV. Dunno if the foam worked, but got 30MPG @65MPH one way, and 26MPG @74MPH the other way (Short distances, flatish), without overheating apparently. Still warry to use that on long trips.