Scangauge tells me to lug it! - Fuelly Forums

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Old 06-12-2007, 10:07 PM   #1
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Scangauge tells me to lug it!

The subject sums it up pretty well.

I've been trying to keep rpms low while driving our 5 around town. Keeping acceleration to a modest clip, I had been limiting rpm to no more than 3000 or so, but based on what I saw today, even that is just too high. Today instead of keeping tabs on the instant MPG display, I was paying more attention to GPH, and even the difference between 4th or 5th gear at 25-30 mph is a difference of 0.2-0.3 GPH at the same speed. Considering that this is the difference between 1500-2000 rpm, that's fairly significant.

So with that in mind, I attempted to keep my revs under 2000 rpm even while accelerating for the freeway (light traffic, nobody cared). This small change took the economy for the school commute from the typical 27-28 mpg to 32 mpg.

Keeping the revs under 2000 isn't really lugging it so long as throttle is relatively light, but it allows me to run through the gears about as quickly as I would at full throttle, so the time spent in low gears is very short.

GPH is the one to watch.
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Old 06-12-2007, 10:17 PM   #2
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My car rarely sees above 1500 RPM (the exception is the highway when it gets up to 1900).



Scangauge strikes again!
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Old 06-13-2007, 04:43 AM   #3
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Snax

Im still finding stuff out about my Civic. It seems it doesn't like lugging at all. If below 1500 rpm and no load at all your ok. But soon as there is any load its toast. The mpg below 1500 rpm loaded. Like trying to make it pull in 5th gear is as bad as being at 4000 rpms sailing the tach twords redline.

I caught myself trying to get it into 5th gear at all coast low in the tach. This was hurting me. Now Im shifting into 5th around 2000 rpm. This is getting the car into 5th gear and in some case's at low load so the semi atkins head, ECU and intake can do there thing. Meaning as long as Im low load then my combustion fuel/air charge is then limited to a 1.5l charge instead of a 1.8l charge. Being below 1500 rpm and above 3000 or 3500 rpm defeats this feature.

Ive always watched out for the upper limit when driving for FE. But really haven't paid much attention to the lower limit. I did do some testing early on with the lower limit. And I found and proved it was working. But then I had a whacky ECU. It took sometime to get that sorted out.

With our Accord It doesn't like to be lugged. The only way to lug it is to get up to 45 to 47 mph and then the AT will lock in 5th gear. It does ok if you let the speed creep down to 40 mph or even 37 mph locked in 5th. But once you get down to 35 and 30 mph locked in 5th the mpg takes a nose dive. So with the Accord its better to let it do as Honda wants and down shift to 4th. Ive seen it locked down to 25 mph. Really takes a light foot to keep it lock. But hurts mpg.

I wish I could look at Hondas programing in there ECU's. As a matter of fact I wish the manufactures in general would let us look at the ECU and tranny control unit programing. If only to help us drive the cars for better FE.

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Old 06-13-2007, 05:59 AM   #4
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I think with the Honda's, accelerate moderate hard, shift b4 the VTEC changes to more aggresive timings and than cruise. I liken it to pulse and glide.
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Old 06-13-2007, 06:55 AM   #5
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I think I've found the limit of what's reasonable in our car at least. On flat ground it seems to be faily unstressed shifting at 2k, which drops it down to about 1200 rpm for the next gear. The only gear that really presents any problem at those limits is 5th with a mild hill. Otherwise with a light load, it will gradually pull all the way up to highway cruising speed from a paltry 25 mph.

I think that it's also useful to be watching timing advance as well. I think timing is probably a good indicator for what amount of lugging is effective. If your computer is keeping timing in the high 20s to 30s, then it's not really loading the motor very hard, but once it drops down into the single digits, an upshift or easing off the throttle are likely to improve efficiency. (Recall that more advance provides more time for a complete burn.)
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Old 06-13-2007, 08:12 AM   #6
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I don't see how you guys are shifting before 1500 rpm's. In my car barely touching the gas gets me at least there. I have been shifting between 2000 and 2500 all the way up to 5th and my last fill up I got 46.8 mpg. Since then I have inflated my tires to 40psi (may do more after this tank, max sidewall on my tires is 51psi) and I am coasting down hills whenever I can, engine on in 5th gear. I hope to get close to 50mpg on this tank.
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Old 06-13-2007, 08:33 AM   #7
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Quote:
Originally Posted by 96hb View Post
I don't see how you guys are shifting before 1500 rpm's. In my car barely touching the gas gets me at least there. I have been shifting between 2000 and 2500 all the way up to 5th and my last fill up I got 46.8 mpg. Since then I have inflated my tires to 40psi (may do more after this tank, max sidewall on my tires is 51psi) and I am coasting down hills whenever I can, engine on in 5th gear. I hope to get close to 50mpg on this tank.
You just gotta drive really slowly!

Welcome to the site, your mileage is already pretty good!
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Old 06-13-2007, 08:37 AM   #8
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You just gotta drive really slowly!

Welcome to the site, your mileage is already pretty good!
Yeah, that is the major adjustment for me ATM. I'm used to running 70 on the freeway home and about 5 over the limit anywhere else. I'm now running 60 on the interstate and trying to stick to the speed limits everywhere else. I am usually in 5th by the time I reach 40mph, but 1st and second I usually get up between 2-3k rpm's before shifting. Every other shift is around 2k and cruising on the interstate in 5th at 60, rpm's are around 2300. So I am getting there. I really wanna see if I can get this car over 50mpg since I commute so far daily. Would be nice.
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Old 06-13-2007, 08:41 AM   #9
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You just gotta drive really slowly!

Welcome to the site, your mileage is already pretty good!
Or hit the gas harder.
I've given up on the slow turtle starts. Boring drive. I think I'm starting to get the hand of quick starts, quick shifts, and coasting. Seems to be working too, last tank which I started on, and this one seem to be my best.

Hit the gas shift Before 2300 rpm
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Old 06-13-2007, 08:42 AM   #10
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>>I don't see how you guys are shifting before 1500 rpm's.

Depends on your transmission gearing. my VX's third gear is close to 1x1 so keeping the RPM shift points low is easier.
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