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-   -   How to increase my mpg?? (98 civic LX 5-speed, AC always on) (https://ecomodder.com/forum/showthread.php/how-increase-my-mpg-98-civic-lx-5-a-23684.html)

mattrich67 10-14-2012 03:21 PM

How to increase my mpg?? (98 civic LX 5-speed, AC always on)
 
I have a 98 civic Lx 4dr lowered timing at 14* (runs a little better then12*)
Tires at 45 psi synthetic oil full tune up valves adjusted new filters.
Just installed my vacuum gauge last week (still trying to figure out the best shifts)
I have to run my a/c since its so hot here in Vegas and I have two kids always with me.

Couple questions.
When I use my vacuum gauge is it better to

I guess what it all comes down to is a higher vacuum 12-25 reading and a higher rpm 3000-3500 reading better then a lower 0-8 vacuum reading and a lower 2000-2500 rpm reading

EXAMPLES:
While shifting should i Keep my vacuum closer to 15-20 (idle) and hold the gears longer and then shift at 3500 so it stays in a good vacuum range after shift or shift at 23-2800 and have the vacuum go closer to 5 in the (poor )

Also when climbing a hill on freeway do I try to stay in fifth and have vacuum readings in 5 poor/ fair or shift to 4th and 3000-4000 rpm and feather the pedal to stay in good 12-18 vacuum readings


Thanks for all your responses and your help

Gealii 10-14-2012 05:03 PM

I couldn't tell you how to drive with a vacuum gauge cuz i never had one but you want to do short shifts. This is basically saying that you want to be in the highest gear you can without lugging the engine. People say they can cruise at a very low rpm without lugging, but as soon as they accelerate it lugs. The goal is to be in the highest gear you can while accelerating without lugging. When i was in my 5speed i would hit 5th gear at 37mph and accelerate in 5th all the way up to cruising speed.

I couldn't tell you about hills only did 1 extreme hill and lets just say i should've shifted down 1 more gear when i got to the top i could smell the clutch.

bestclimb 10-14-2012 07:20 PM

unless you need to shift down to avoid slowing down too much on the highway leave it in 5th gear and let the speed drop off just a tad while going up hill, you can get the speed back up on the next down hill or flat. Really the best thing to help your mileage is data, get an instant fuel consumption display of some sort you will be able to see for your self. It will pay for it self.

nmtmechengineer 10-15-2012 01:35 AM

I used to use a vacuum gauge back in college on my 87 Celica, so I can relate to this question. Although it depends on if you are driving in the city or high way. I used to use the hypermiling techniques before I read about them. Driving with load or rolling to an intersection without stopping.

What looked at was the engine dyno for the engine in my car which was a 3S-FE Toyota engine. It had a pretty flat torque across the RPM range. Thus I shifted at a lower RPM. In addition, it made sense to me because for most calculations regarding force the velocity is squared.

BTW the vacuum gauge I mostly used on the open road or highways because it is very sensitive to the gas petal input.

Just my 2 cents.

California98Civic 10-15-2012 03:05 AM

Use the search function for other threads, but here is one that will help you: http://ecomodder.com/forum/showthrea...uge-21278.html

j

mattrich67 10-15-2012 03:42 AM

Thanks for all the replies.

I have tried for a week and a half now to get the best mileage I can and I'm not gaining as much as I would have liked. I have gone from 25 mpg from the first tank after I bought it. ( it was sitting for 6 months ) these last two tanks I have only got 32 mpg withy the a/c on and that's with coasting to lights 65 freeway prob 60 town 40 freeway. I have been using the vacuum gauge and try very hard to keep that vacuum anywhere from 5-15 driving and then feather the pedal after I hit my speed goal.

How are you guys getting such awesome mpg. I thought with me driving like a grandmas grandma would get me maybe 40 with the mix driving and a/c but when I only saw 60 miles and its already in between full and 3/4 tank I don't know if its worth driving that cautious and that much concentration.

Is it me or something up with the car. I have changed everything and did all the fluids. It seems a little sluggish when I hit any type of incline. Seem like I always have to shift down??

mattrich67 10-15-2012 03:45 AM

I have a Mac tools scanner that has live data is there anything I can look at or test to see of something is not correct? O2s iat load or short fuel trim long fuel trim?

Thanks again

MetroMPG 10-15-2012 11:31 AM

First: consider more active use of the a/c - shut it off on grades or other times when the added load would otherwise make a downshift necessary. Turn it back on when cruising or when you have to decelerate in gear (DFCO).

Second: going by the fuel gauge is a lousy way to estimate your current fuel economy. It's not accurate enough. You really need a digital MPG gauge - ScanGauge or equivalent if you want to know fuel consumption use in-between fill-ups.

Third: in my opinion, focusing on how to use the accelerator is not where you should be spending your efforts (at least in city driving). Get in the highest gear you can, then worry about the brake pedal - It's the enemy of good city MPG. You should be driving without brakes as much as possible, looking far ahead in traffic, planning & anticipating, and coasting as long as possible in neutral when approaching stops/turns (without impeding traffic!). Every time you hit the brakes, give yourself a dope slap.

Fourth: how realistic are your expectations? 25 mpg to 32 mpg is a pretty big improvement already. That's a 28% increase! And you're apparently beating your highway MPG rating now.

When you ask "How are you guys getting such awesome mpg?", which guys are you talking about?

The Civic owners getting extreme MPG are not using the A/C, they're definitely not cruising at 65 mph on the highway, and they're definitely not driving like Grandma ever did! They're using advanced techniques that may not be appropriate for you or your driving environment. http://ecomodder.com/forum/EM-hyperm...ecodriving.php

mattrich67 10-15-2012 12:09 PM

Wow!!

The best way to calculate fuel mileage is how much fuel you use on gas gauge. And if I only go 150 miles on a half a tank I know I'm not getting but more then 30-35 mpg. If I got like 200 miles on half a tank I know I'm doing right.

Anybody can trick a on board computer. I do it all the time in my scion xb. I can get that to read in the 30 mpg range but when you do the real math and calculate the miles to gallons and read 24 mpg not 30 then you know you can't fully trust a on board gauge.

3rd
When my civic is supposed to get 28 mpg city only that's what I expect on a average driver. Now since I'm driving slower at takeoff, coasting to a stop, shifting under 3000 rpm, and driving the most efficient as I am able to do. I would think that I could make at least 5-8 mpg better.
Also my 32 mpg is 40% freeway

Fourth : thanks for that advise

Fifth :
I have seen over and over civic owners non hybrid getting 40- 50 mpg with only changing driving habits and maybe a grill block.
That's why I am asking and if they can get 50 mpg why can't I get 40 mpg.

OR are they going by a scan gauge readout!?

And yes the ones I saw did go 60-65 mph on freeway.

OR

Are these people live in a town that's all flat ground no hills just smooth drive nice wheather

This is the stuff I am asking.

MetroMPG 10-15-2012 12:38 PM

Of course you're right: the final word goes to miles divided by gallons at fill-up time.

But if you want the most useful feedback between fill-ups, use a resettable, properly calibrated digital fuel economy gauge. The overwhelming majority of "high MPG" drivers here use them for that reason.

Saying "I'm not getting but more then 30-35 mpg" by the position of the needle on the fuel gauge just isn't accurate or timely enough to use as feedback.

Gealii 10-15-2012 12:39 PM

Chances are those civics are either taking advantage of the lean burn function or they are engine off coasting. Shifting sooner if your shifting under 3000 try lower if you can shift up and not lug the engine its a plus.

Civics are probably using a device of some kind thats aftermarket whether its a scangauge or mpguino. Mpguinos are popular on civics because they give the fuel readouts during leanburn

mattrich67 10-15-2012 12:59 PM

Thanks Gealii

I'm not saying 32 mpg is bad. But if I can drive regular with out paying 90% of my attention to how I drive and get 29 mpg or close to it I don't know if its worth that much attention. And effort. But if I can do this and get 35++ then yeah it's fun and beneficial.

I'm looking to get a scan gauge here in the next couple weeks. So we will see what increase I get.

PaleMelanesian 10-15-2012 01:02 PM

Shift sooner. Keep it under 2000 until you get to cruising speed and the gearing won't allow you to go that low. When you're accelerating, go ahead and use the "poor" vacuum reading and keep the rpm low. (Autospeed article explaining BSFC)

AC. Consider using it less. I live in Texas. I don't need it in the morning (with kids on board going to school). In the afternoon I wish mine weren't broken - I'll give you that one.

Coast in neutral - actively look for places where you can. There are a lot more than you'd think, once you start looking. The engine is idling at ~800 rpm instead of 2000+, so it uses less gas.

Oh, and I second and third the idea of getting a gauge. With calibration, they can be VERY accurate. And it will open your eyes as to what works and doesn't work for mileage. Minute-by-minute feedback is so much better than trying to guess from the fuel level.

bestclimb 10-15-2012 01:09 PM

Quote:

Originally Posted by mattrich67 (Post 334181)
Wow!!

The best way to calculate fuel mileage is how much fuel you use on gas gauge. And if I only go 150 miles on a half a tank I know I'm not getting but more then 30-35 mpg. If I got like 200 miles on half a tank I know I'm doing right.

Anybody can trick a on board computer. I do it all the time in my scion xb. I can get that to read in the 30 mpg range but when you do the real math and calculate the miles to gallons and read 24 mpg not 30 then you know you can't fully trust a on board gauge.


that works and I have done that but an instantaneous fuel usage gauge is orders of magnitude better. Ultra Gauge, Scan Gauge or MPGuino. I am partial to the Ultra Gauge for it's display and lower price point than the Scan Gauge. The mpguino as stated is the one to get if your car has lean burn.

The aftermarket ones have the capacity to be calibrated. a built in one that is incacurate is still a good indicator if you calibrate your head to it.

Quote:

Originally Posted by mattrich67 (Post 334181)
3rd
When my civic is supposed to get 28 mpg city only that's what I expect on a average driver. Now since I'm driving slower at takeoff, coasting to a stop, shifting under 3000 rpm, and driving the most efficient as I am able to do. I would think that I could make at least 5-8 mpg better.
Also my 32 mpg is 40% freeway

Fourth : thanks for that advise

You may be taking off too slowly. I am kind of a fan of moderately heavy acceleration (at a lowish RPM). you use more fuel quickly but are up to an efficient cruising speed sooner.

The biggest gains as long as you are not lugging up to speed or flooring it and winding it near red line before shifting is made in how you slow down. try not to use your brakes.

and you are welcome.

Quote:

Originally Posted by mattrich67 (Post 334181)
Fifth :
I have seen over and over civic owners non hybrid getting 40- 50 mpg with only changing driving habits and maybe a grill block.
That's why I am asking and if they can get 50 mpg why can't I get 40 mpg.

OR are they going by a scan gauge readout!?

And yes the ones I saw did go 60-65 mph on freeway.

OR

Are these people live in a town that's all flat ground no hills just smooth drive nice wheather

This is the stuff I am asking.

I think most of us go by miles traveled divided by the fuel put in the car. Our guages are calibrated pretty closely (my MPGuino was within 1% of the tank)

Hills are a good thing. up using a high load (less throttling losses) and down at nearly no fuel. for instance my flat and level 50mph consumption is 40mpg. Up hill I can get 25mpg. Down the same hill I am not using any. RT fuel for the hill is 50mpg (this is in my escort. My civic was about 10mpg better for all the values)

Good luck

California98Civic 10-15-2012 01:17 PM

Get an Ultra Gauge because it is cheaper than the ScanGauge and simpler to install and possesses more abilities than the MPGuino. When you get it, I promise that if you are driving a manual Civic we'll be able to show you how to improve your numbers. The UltraGauge will pay for itself in 3-10 tanks, depending on how effectively you use it.

Pulse and glide technique works best with a good gauge and the practice of coasting (where safe!) with the engine off. Pulse and glide is the best MPG move on the whole list, if you learn to accelerate in the best load range and if you learn the art of coasting with the engine off.

In the mean time, shift around 2000 or 2200 rpms instead of 3000. And slow down a little more even: 60mph on the freeway is perfectly legal and not an obstruction and it's a mile per minute!

james

kennybobby 10-15-2012 02:41 PM

i don't know if a BSFC curve is out there for your engine, but after looking at all of them that i could find and making CALCULATIONS of fuel consumption for various acceleration profiles up to a given speed--i found that the best acceleration technique is to rev it on up at the more-efficient highest power and torque region rather than prolong and drag out the acceleration for a longer time period at a lower power level (grandpa mode).

For example using 100 hp vs 60 hp to accelerate up to 60 mph used ~30% less fuel to cover the same distance. This works because you are using the fuel most efficiently, albeit at a higher rate, but for a shorter time.

i tested this on my BA van and mileage went up from 13's to 16's. i tested it on my VFR750 motorsickle and mileage went up from low 30's to low 40's. i'm also using coast in neutral, and staying off the brakes, which is probably the biggest factor, but it's definitely made it more fun to drive...i used to accelerate like grandpa, like there was an egg under the pedal--not anymore, i get on that thing hard at WOT when accelerating up to cruising speed.

What this means is that you want to get down into 1-4 on the vacuum gauge when accelerating and rev it on up to where the engine is making it's most efficient torque. If you are then at cruising speed go ahead and double or triple shift it up into highest gear. Try it you might like it and be surprised at the results.

mattrich67 10-15-2012 02:49 PM

Now these are the responses that I have been trying to get. This helps me and probably a lot of others to realize and understand.

I also was thinking I was accelerating to slow and dragging out the gear to long rather then getting to the desired speed and then pulse and glide or coast.

I have been shutting off the a/c when I am pulling a hill or needing to speed up like getting on the freeway. And it helps.

My last civic was the same year make model and I remember getting 280-320 to the tank averaging 32-38 mpg and that was just driving however now I have this civic and I am trying to get the best gas mileage and I get the same as I would with the old civic without trying. Haha

mattrich67 10-15-2012 02:53 PM

What gauge do you guys recommend

Scan gauge 2

MPGuino

Ultra gauge

I get so excited reading these posts and replies I just want to go drive around Vegas and see how much I can improve tank to tank

MetroMPG 10-15-2012 02:58 PM

Please put your car in the garage and start a fuel log so we can watch your progress:

Your Garage: [ Add new vehicle ]

bestclimb 10-15-2012 04:24 PM

Quote:

Originally Posted by mattrich67 (Post 334227)
What gauge do you guys recommend

Scan gauge 2

MPGuino

Ultra gauge

I get so excited reading these posts and replies I just want to go drive around Vegas and see how much I can improve tank to tank

any are good. I have used a MPGuino in my civic (sold the car kept the gauge) I currently use an Ultra Gauge.

I like that the MPGuino reads the raw data from the VSS and injectors, so it's accuracy (once calibrated) can be very very good.

I like that the UG and SG give more than just fuel and speed information such as trouble codes raw sensor and what not. and they are accurate enough in the MPG department for my uses.

Gealii 10-15-2012 04:46 PM

I would go with the Ultragauge at least at first. The only reason i see getting a scangauge is if you have a hybrid. The Ultragauge has all the same functions as a scangauge minus the hybrid help. It can be used as a code reader, is more accurate the factory needle gauges, and can be calibrated to closer to your mpg readouts. The ultragauge is also much cheaper than a scangauge. And plugging into the obd2 port makes it easily exchangeable to another vehicle

serialk11r 10-15-2012 05:58 PM

The guys who are saying keep it under 2000 or whatever, are you sure about this? These small engines tend to hit peak efficiency at slightly higher rpms. My 1ZZ is not a Honda D16 but the 2 are quite similar (91.5mm stroke vs. 90mm stroke, I have 1.794L though), and while there are no published complete BSFC charts that I know of the peak thermal efficiency at maximum load is at 3200rpm or so.

Additionally, I can't go up a very (emphasis on the very) slight incline in 5th below 1600rpm, because the engine bogs. If I hold at 1600rpm (about 30mph) on flat ground my mpg is only so so, high 30s ish. When I go up to 2000rpm or about 36mph then I'm getting 45mpg or so. If I try to hold 1000 rpm, I need so much load that I only get 30mpg according to Torque. Hence, I try to not dip below 1700 unless I'm coasting in gear to a stop. For those pesky 25mph roads I tend to accelerate and then put it in 5th and give barely any throttle so it doesn't DFCO on me. That way I don't need to put in neutral and idle (depending on the ECU's mood the idle can be as high as 1200rpm sometimes :/, or as low as 600), which consumes only marginally less fuel than having the engine do a tiny bit of work in 5th, and makes rev matching a downshift easier, as well as giving me the option of DFCOing.

California98Civic 10-15-2012 09:52 PM

Quote:

Originally Posted by serialk11r (Post 334299)
The guys who are saying keep it under 2000 or whatever, are you sure about this? These small engines tend to hit peak efficiency at slightly higher rpms. My 1ZZ is not a Honda D16 but the 2 are quite similar (91.5mm stroke vs. 90mm stroke, I have 1.794L though), and while there are no published complete BSFC charts that I know of the peak thermal efficiency at maximum load is at 3200rpm or so.

Additionally, I can't go up a very (emphasis on the very) slight incline in 5th below 1600rpm, because the engine bogs. If I hold at 1600rpm (about 30mph) on flat ground my mpg is only so so, high 30s ish. When I go up to 2000rpm or about 36mph then I'm getting 45mpg or so. If I try to hold 1000 rpm, I need so much load that I only get 30mpg according to Torque. Hence, I try to not dip below 1700 unless I'm coasting in gear to a stop. For those pesky 25mph roads I tend to accelerate and then put it in 5th and give barely any throttle so it doesn't DFCO on me. That way I don't need to put in neutral and idle (depending on the ECU's mood the idle can be as high as 1200rpm sometimes :/, or as low as 600), which consumes only marginally less fuel than having the engine do a tiny bit of work in 5th, and makes rev matching a downshift easier, as well as giving me the option of DFCOing.

I know it might seem counter-intuitive but it seems to work well. Look at Palemelanesian's PaleCivic fuel log. He accelerates between 1500 and 2000 rpm at about 80% load. I do about the same, often 2200 RPMs. A distinction worth something might be that we're not at "maximum load" as you say, if by that you mean WOT and 100% load. We are at maybe 30% throttle and seeking about 80% load, which is generally regarded as the best region on the BSFC map for fuel economy purposes. I'm not claiming expertise, just experience. It works, and lots of guys here argue this is why.

serialk11r 10-15-2012 11:53 PM

Quote:

Originally Posted by California98Civic (Post 334344)
I know it might seem counter-intuitive but it seems to work well. Look at Palemelanesian's PaleCivic fuel log. He accelerates between 1500 and 2000 rpm at about 80% load. I do about the same, often 2200 RPMs. A distinction worth something might be that we're not at "maximum load" as you say, if by that you mean WOT and 100% load. We are at maybe 30% throttle and seeking about 80% load, which is generally regarded as the best region on the BSFC map for fuel economy purposes. I'm not claiming expertise, just experience. It works, and lots of guys here argue this is why.

Oh, I understand that. I also accelerate at 70-80% load. I also understand that at lower load, the peak BSFC comes at a lower rpm. For example the S2000 has best 100% load BSFC at ~4700rpm eyeballing it off the chart, but the peak efficiency arrives at 3000rpm.

What I have trouble believing is that the efficiency at 1500-2000rpm is better than it is at say 2000-2500. Most engines have their efficiency falling off at all load levels below 2000rpm. I try to get out of first early if I don't need to immediately accelerate since 2nd gear has much more controllable power on my short geared car, but otherwise I shift at 3000 to avoid landing much below 2000rpm in 2nd.

My car can be driven if I use the 1500-2500rpm range only and I'd prefer to use that range because it makes the shifts easier, but I have a strong suspicion that at 1500rpm the engine's efficiency is already pretty crappy. Maybe my engine is just in bad shape. The only hard and fast numbers I have are 1500rpm in 5th seems to get less mpg than 2000rpm in 5th, which is my best steady state cruise speed. On a road that I know is pretty much completely flat, to hold 1500rpm in 5th requires a somewhat high load, and Torque (which can read fuel flow rate and OBDII speed) seems to suggest that 4th (1900rpm) gives slightly more mpg than 5th. My 5th gear is about the same number of revs per mile as the 6th gear on an AP2 Honda S2000, so we're talking VERY short.

I'd like to do more testing on this as I do a few more tune up things to my engine. I don't burn through gas very fast so it's hard to do tank to tank testing. Yesterday Torque said I got 33mpg on a 50 mile drive even though I was pulse and gliding most of the time on the highway below 60mph, and drafting a semi...perhaps it's just my engine needing some work.

PaleMelanesian 10-16-2012 10:19 AM

I've been doing this for a few years now and I've tried all the combinations of load and rpm. 1500-2000 (sometimes 2200) and 80-90% load (13 psi MAP) is the best for mileage in these Hondas. On flat ground I can gain speed from as low as 1000 rpm, so 1500 is a conservative limit you can stretch and go lower if you like.

mattrich67 10-16-2012 11:03 AM

I just purchased my ultra gauge so I will let you guys know what I find out

PaleMelanesian 10-16-2012 11:37 AM

Excellent! You won't regret it.

mattrich67 10-16-2012 03:26 PM

I didn't know about the ultra gauge. I was looking to buy the scan gauge everyone talks about. But I just did want to spend 180$ for one yet. But for the 1/3 of the price and everyone says its easier to use and does all the same stuff unless u have a hybrid.

I spent 80$ for the gauge and all 3 mounting brackets windshield the Velcro and clip so then I can mount a bracket in my 08 xb and have fun

mattrich67 10-17-2012 02:55 AM

So i can be prepared when i get this ultra gauge what are the main displays should i be using and what should i want to read off of them when driving? :thumbup:

also one thing i have been forgetting to ask is what should my air intake temp be reading at?

Gealii 10-17-2012 05:26 AM

Quote:

Originally Posted by mattrich67 (Post 334625)
So i can be prepared when i get this ultra gauge what are the main displays should i be using and what should i want to read off of them when driving? :thumbup:

also one thing i have been forgetting to ask is what should my air intake temp be reading at?

Everyones gauges are different but i run
instant mpg, avg mpg, air intake temp, engine temp, engine load %, rpm

Your air intake temp is probably reading close to the outside air temp considering most cars come with a cai or close to it. But the warmer the intake air is the better

kennybobby 10-17-2012 09:48 AM

Acceleration Duration?
 
Quote:

Originally Posted by PaleMelanesian (Post 334431)
I've been doing this for a few years now and I've tried all the combinations of load and rpm. 1500-2000 (sometimes 2200) and 80-90% load (13 psi MAP) is the best for mileage in these Hondas. On flat ground I can gain speed from as low as 1000 rpm, so 1500 is a conservative limit you can stretch and go lower if you like.

Hey PaleMel there is no messing with success and i have seen some of your impressive data and results in other posts, so you definitely know how to drive those hondas.

Let me ask you what is your typical acceleration times to get up to 40 mph and up to 60 mph from rest--in units of time in seconds or minutes :D such as the case may be...?

PaleMelanesian 10-17-2012 10:25 AM

Well, I usually don't hit 60 at all, since only one short stretch of my commute is even 55 mph limit. That's part of my secret: a good route.

I haven't measured, but it's probably about 15 sec to 40 mph. I'm still in the ballpark of other traffic while accelerating. 1st gear only to get rolling (5-10 ft), 2nd up to 10 mph, 3rd up to 20 mph, then 4th gear up to 40. I usually stop there and glide down to 20, then pulse back to 40. If I'm in a hurry I'll use 5th gear with 30-50 mph pulse-and-glide instead, and lose about 5% mpg.

Gauges to use (I have Scanguage which shows 4):
  • Trip mpg - my most important gauge. Keep this moving up for the entire trip. If you must lose some on a hill, gain it back and more on the other side.
  • Load - 85-90% load for acceleration is most efficient.
  • water temp - for diagnostics
  • volts - for diagnostics, especially with engine-off coasting and headlights
  • instant mpg - if I had another spot, I'd show this one

bestclimb 10-17-2012 12:05 PM

I like the 6 guage screen page 1 to have MPG instant, %load, MPG AVE, UG volt, short trip MPG, DTE

page 2 gets the same except trip MPG instead of mpg ave and trip gallons used instead of UG voltage.

The next 2 pages have engine type guages rpm, temps and the like.

California98Civic 10-17-2012 12:08 PM

Quote:

Originally Posted by PaleMelanesian (Post 334659)
[*]Load - 85-90% load for acceleration is most efficient.

Whoa. You keep upping that number, no? I seem to recal you saying once that you thought over 80 was a waste. Then that you sought low mid 80s (I think), but suggesting as high as 90% is striking. I have to wonder if that would work on my very hilly route, where I unavoidably get stuck even at lights, on a steep incline 1-3 times per leg of my daily commute. Would you describe your experience more?

PaleMelanesian 10-17-2012 02:17 PM

I changed my approach since Sentra did his instrumented study on pulse loads. His best was 92%. I watched my Loop gauge more and determined that it's actually hard to hit Open Loop. I was initially fooled, because the first 3 seconds it really wants to go open loop. Once it gets past that, it locks in Closed Loop until well above 95 LOD. So now I target upper 80's to 90, trying not to pass 95. I *think* that change was one factor in my 90 mpg tank this summer, beating last summer's 88.

Oh, and I confirmed my 15-sec 0-40 acceleration.

mattrich67 10-17-2012 02:45 PM

That's very smart. I never thought about watching open and closed loop. If u can run in closed loop that would give the computer Ecu to run in its best cleanest fuel mixture possible.

These are great things to look for.

Thanks for the advise palemelanesian

mattrich67 10-17-2012 02:53 PM

Hey palemelanesian

So lets see here a couple things if I'm learning correctly

80-90% load as long as I am in closed loop
Short shifts (try to be under 2000 rpm)
Stay in closed loop

What about TPS % I hear a lot of different things?
What is a good WAI Temp or do you look at this?

Also I know people say coast in neautral to a light but what if I'm coming to a stop should I downshift and use my gears to slow down? Doesn't it go into lean mode if I do this?
Coasting in neutral just goes into reguluar idle fuel mixture reading doesn't it?

California98Civic 10-17-2012 03:38 PM

Quote:

Originally Posted by PaleMelanesian (Post 334686)
I changed my approach since Sentra did his instrumented study on pulse loads.

But Sentra drives an Xb, right? You're confident the BSFC map is similar, I take it.

PaleMelanesian 10-17-2012 03:46 PM

I used his testing as an incentive to try some new things. It seems to work for me, so I'm going to keep doing it the new way.

Matt:
TPS is related to LOD but less useful. To get 80% load at low rpm doesn't take much throttle opening at all, while at higher rpm you really have to bury the pedal. LOD is a constant target no matter what rpm you're running.

Engine braking is good IF you have to brake. If you can plan ahead and coast to a stop, that's better. If a light changes or a traffic event forces you to bleed off speed, engine braking is good. Above 1200 rpm, our cars shut off the fuel completely, letting the wheels drive the dead engine. When it gets below 1200 it turns the injectors back on to avoid stalling.

serialk11r 10-17-2012 04:02 PM

Hmmm 85% load...that's quite high!
It's hard to tell what load has the best BSFC, but most engines seem to be within 15% of peak efficiency by 50% load. I think this has to do with the fact that higher combustion pressure starts to be wasted after ~50%. More power offsets the proportionally higher friction at low load though, so peak efficiency comes at higher loads. I think any OBDII car keeps closed loop even at WOT below some engine speed, I know mine does.

I try to use 60-70% load to accelerate because it offers most of the efficiency but makes controlling acceleration and avoiding braking much easier. Additionally, when pulse and gliding, the longer pulse may consume a bit more fuel but I think it reduces the proportion of transient conditions (needing to rev the engine back up) and idle. I love slightly hilly highways because I can pulse up the incline at 50-60% load without building speed at all, and then drop into neutral down the hill and lose speed slowly. But most importantly the lower load makes it easier to drive since there's less power coming on. With my featherweight car and absurdly short gears this is especially an issue, although your Civics aren't much heavier! I ditched my spare for luggage space so I should be at 2175-2180lbs with full tank of gas.


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