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Engine-Off-Coast
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Discussion Starter #1 (Edited)
When I'm driving sometimes I can see on the instant fuel economy bar graph that the car is going into lean burn. I want to hold it there, but it seems as though the power the car outputs while in lean burn is just a little too weak and so I can't "cruise" in LB. The car will slowly decelerate and then I have to hit the gas to get back to whatever speed I was going at.

There are a number of factors working against the car right now, so maybe y'all can identify which are the biggest issues?

- No IMA right now, my cousin and I are reconditioning a bunch of sticks, It'll probably be done in a couple weeks. We're doing his car's IMA pack first.
- It's cold outside. ( Canada )
- Missing three aerodynamic pieces under the front of the car. I'm on the wait list for one of those custom aluminum pans, that will replace all missing panels. I still have the big panels in the middle of the car and the strakes so that's good.
- I don't have LRR tires because winter. However, I did switch to Civic VX rims so at least the wheels are very light.

The IMA and missing aero components are just waiting-game type issues that will be resolved in the future. But I'm looking for solutions I can implement sooner than that. For example, I'm considering making an aerodynamic upper grill block.

The car is a 2001 and it has about 130K miles on it. I cleaned the EGR valve and changed the transmission fluid and oil about 1000 miles ago, but are there possibly other maintenance issues that I could look at to improve power in LB or at least let it cruise in LB? I can *barely* maintain 45 mph on a flat surface in LB.
 

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hmm, something sounds amiss - you should be able to maintain lean burn pretty easily at say 60-65 mph cruising on the highway... IMA won't have any bearing on your situation.

First would be the tires - depending on what you've got, it could be a huge difference or it could be a ... difference. I wouldn't think the same sized tires, just not LRR, would make too much of a difference; if you have over-sized winter tires - that could be the difference between say being able to lean burn at 65 mph vs. 55 mph (I'm kind of just making these numbers up, seems reasonable to me though).

The aero panels might be a couple mph difference...

I don't think cold weather would make much of a difference once the car's warmed up and you're cruising, but I'm not an expert on that... In general, cold weather does make it harder to lean burn, and I suppose that margin, teetering on the edge, even if you're cruising, can lower the speed you're able to maintain - so I guess I'd put that at a couple mph, too...

I'll leave it up to the experts to add anything else...
 

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Hypermiler
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You've mentioned 3 fairly strong contributors to increased resistance to 'gliding' through air: cold (cold here too), tires, and aero panels. But as eq mentioned, you should be able to hold lean burn, maybe not at the high mpg you'd normally get in better weather. Any snow or ice on the road is just more resistance to fight.

If you have an obdiic&c, you could monitor 'load', throttle position, or 'fuel injector duration' (I watch the last one). After getting into burn, VERY gently ease more into the throttle, but not so aggressively as to kick out of burn. I've learned to see and feel where the max engine load is before it wants to kick out of burn. I watch the fcd drop off too and 'settle for mid 70's or so on mpg.

If you don't have the obd, you could kind of 'feel' where the car wants to kick out of burn and stay under that threshold.

You may also consider airing up the tires a bit. A tough balance there with snow and ice on the roads.

fwiw: I was missing the 3 front aero panels under my mt. After installing Scotts' belly pan I saw an increase of 5% on the mpg.
 

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I find the same thing...

I can get into LB, and know I'm there since it'll "burp" when it should. If I'm doing 60, the car will gradually loose speed, and I have to hit the gas to increase speed, and fall out of LB. I've been wondering if there's something wrong w/ the car or with the driver :)

<== no ima and missing strakes and the passenger side under engine peice.
 

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When did you notice the poor lean burn performance? That might be a clue.

My vote for the elephant in the room is the winter tires. Nothing beats the RE92 LLR by a wide margin.

In addition to the factors mentioned, the constant cold intake air temperature is a negative. Also the density of cold air. All-in-all you have everything working against you.

I personally think that the car is normally challenged to maintain LB at 65mph under the conditions you mention.
 

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I personally think that the car is normally challenged to maintain LB at 65mph under the conditions you mention.
Tall gearing, but if you drop to 55mph its even harder. Maybe 4th gear would actually raise mileage at that speed?
 

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No IMA you say? What IMA codes do you have? Some IMA codes will disable lean burn, and make it impossible to even enter LB mode.
 

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Engine-Off-Coast
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Discussion Starter #9
@Balto:
Not sure what code, I forget, but it does enter lean burn. It just can't maintain it. I'm in Canada so I use metric settings, the FCD instant fuel economy will drop to about 2 L/100km which indicates lean burn to me and yeah there is a small range of throttle available, but if you push too hard then the fuel economy goes back to a normal 4 L/100km situation and the engine sounds different. I am like 95% certain it is going into LB.

Weather right now has been slightly above freezing. I've been trying to stay in LB at speeds of about 45mph typically in 5th gear but it just can't hold it. I'm not attempting this in precipitation, I'm talking about clear days sun out, nothing on the road, mostly flat driving.
 

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....Weather right now has been slightly above freezing. I've been trying to stay in LB at speeds of about 45mph typically in 5th gear but it just can't hold it. I'm not attempting this in precipitation, I'm talking about clear days sun out, nothing on the road, mostly flat driving.
My guess would be that the car will get better mileage in 4th at 45 mph, since the engine is close to 2000 rpm. This is the area of the engine where fuel is burnt more efficiently for a given amount of HP, related to the BSFC map, especially if the engine load is higher, like in the winter. If it were hot outside, like in the summer, then I would pick 5th gear for cruising.

Also, jime mentioned air density and the difference in air density between 70F and 0F is 15.2%, so it is a big factor. If it's colder than 0F outside, then the difference is more.

Jim.
 

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My experiencewith my 2000 in cold

Intake air heater made a big 105 difference when very cold here freezing or below.
Make a aero block for thr grill, another large help in winter. I believe the car has to use fuel to allow engine heat to be made to warm car interior under freezing...
Try those:) I thiink you will like the results. My undertray is plastic sign cardboard stuff...great here, ice, not so much... May need to wait till warm weather or the metal one gets done..
Good luck.
 

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What tires do you have on? I have snow tires on mine. You instantly loose 10mpg or more using snow tires. Holding lean burn becomes almost impossible with snow tires. Add onto the fact that civic VX rims are not aerodynamic as the insight wheels are.

Edit: As someone else mentioned the cold air temp is huge drop in lean burn ability. You would need to reroute air intake or modify the front grill vents.
 

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I recomend doing BOTH... Grill block AND Intake air heater!

Grill block AND intake air heater, BOTH help, here, in WInter. I KNOW that the extra cold you are dealing with THERE would respond even better to these mods. Our engines need to run on hot side of temperatures to stay in LB...and the hotter you get the engine (without overheating it, of course) the easieraccessing LB, can stay in LB longer, and more mpg increase you will achieve in LB with these mods.

I base this on MY DRIVING experience's last New years, primarily, when I drove out to Ft Riley, KS to see my son. (He's a MP in the Army, there. It was 19degrees, tops, during the day! when I got there NY eve, and stayed freezing or below till I left! Waaay cold to me (from ALabama!) Car did GREAT otherwise, but mpg plummeted to low 40's with heat on full force, constantly! Heat off, back to mid 40's 46-48(at 80+mph), ( w/o strong headwind to 49- 52 or 3 when heat off at 80 on Interstate. The headwind, at about 40-50 gusting mph, made a significant difference in mpg's, over time and many miles, as compared to coming home, same temperatures, with a tailwind of probably 20-30 mph.
I got 52 to 54 mpg at 80+ flowing with traffic . (heat on full blast)!

NOTE!! This was BEFORE any heat reclamation modifications!!

When I analyzed this I realized how little fuel is flowing at 60 or even 45 mpg's! Thats a gallon every 45 minutes (or so). AT 60mpg's a gallon per hour.
Think about flowing that fuel constantly for one hour! Thats a SMALL (coffee straw?) stream (actually much ess than that still trying to visualize it!) but a VER, VERY small quantity of fuel burning, thus heat energy being produced to heat the car! MUCH LESS push it 75-85mph down the road! The compression/combustion, less friction losses, HAS to be making more heat, than simply burning a gallon ofgasoline NA for one hour!

Sooo, thats what I realized. WOW, I don't want to or definitely don't NEED to allow heat to go unused/uncaptured and be wasted into atmosphere!

Thats when I got SERIOUS about retaining/reclaiming/recycling heat energy lost in WInter. (In these cars)...anyway.
I made a grill block from a sheet of (coroplast?) the plastic cardboard sign material (buy at Home Depot or better yet, Lowes if close by, cheaper there).
What I did, results and recomendation's:)!
A.
(1) sheet made my grill block (actually 2grill blocks were made, one for Spring and Fall, one for WInter that blocks EVERYTHING, still NEVER close to overheating so safe for sure:).
I noticed a minimum 5 mpg bump(increase) from the Grill Block w/o trying, and 10+ when trying to "milk" it...That used approx 1/2 sheet (4x8').

The other portion of the coroplast, I cut into a undertray/belly pan. I used 6 self tapping bits (roofing style 8 mm heads) to attach with fender washers to spread the load of the belly pan. Its light but wind can grab it, and the washers will prevent it from being ripped free, hopefully! hehe Make sure toinstall it with the front "lip" UNDERNEATH the front plastic transition piece(black plastic coming off the chin spoiler) to keep air from catching under it and ripping everything off the car.

B.
One 3' (or whatever it comes in) "roll" of collapsiblealuminum dryer vent pipe. I wired it to the Housing surrounding the Cat converter (upper one) closest to head as possible re intake of it. Over the head (kinda "nestled" somewhat in A/C lines, then into the area in front of engine above intake runners, and onto the plastic snorkel that is the intake air access. I squeezed down onto the intake as best I could by hand may te it for a better seal later.
I used "piano wire" to attach the other end to the cat converter shroud.
Ran all last Winter (until April end) w/o ANY issues , just faster warm up to operating temperatures, and better mpg's (3 to 5 mpg's everywhere, I'd say). Seems to not degrade piower or tq output of the engine when not in LB. In LB, it definitely helps.
LB is much easier to access and stay in in Winter with this attached. Engine warms up noticably faster, and will maintain LB approx 3 to 5 mph faster speed. Instead of say 55 pretty much all the time, its 58 to 59/60 maintained. Also doesn't jump out of LB as fasgoing up a hill...SOme of this MAY be Grill block helping, as I do both at the same time and day.

This helps IMHO primarily from not needing extra fuel to be used so heater can heat car to desired temperature inside on cold days/nights. Catching, and not allowing heat from exhaust and wasted by radiator and engine block cooling indirectly, from air interacting even with thermostat locked closed, leaves no alternative EXCEPT the engine to burn fuel to make heat for the heater to use to heat the cabin. Reclaim the exhaust heat, and reduce unwanted/unneeded cooling from air swirling into the engine compartment, further cooling the engine more than is wanted/needed.


The post I searched and found had a video, I believe, or a series of pictures, at least, showing the installation of the dryer material to the intake. The piano wire atachment was my idea/modification to the installation.
YMMV

Happy gas mpg's increase!
 

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Mileage increase with Scott's Belly pan

I'm seeing the same mileage improvement with Scott's belly pan as Mountain Driver saw in his earlier post.

I installed Scott's belly pan on my original Silver 2000 MT about 4 weeks ago. Stock belly pan components were in very good shape but I wanted to see if a more aerodynamic pan would improve my mileage. I also wanted to make my oil changes easier.

I drive this 2000 MT to work every day over the same course. The best mileage I was able to get was low 60s over a hilly socal course (1600 ft elevation gain/loss). With the pan I'm well over 65 mpg for the last tank. This vehicle has Michelin tires.

You've mentioned 3 fairly strong contributors to increased resistance to 'gliding' through air: cold (cold here too), tires, and aero panels. But as eq mentioned, you should be able to hold lean burn, maybe not at the high mpg you'd normally get in better weather. Any snow or ice on the road is just more resistance to fight.

If you have an obdiic&c, you could monitor 'load', throttle position, or 'fuel injector duration' (I watch the last one). After getting into burn, VERY gently ease more into the throttle, but not so aggressively as to kick out of burn. I've learned to see and feel where the max engine load is before it wants to kick out of burn. I watch the fcd drop off too and 'settle for mid 70's or so on mpg.

If you don't have the obd, you could kind of 'feel' where the car wants to kick out of burn and stay under that threshold.

You may also consider airing up the tires a bit. A tough balance there with snow and ice on the roads.

fwiw: I was missing the 3 front aero panels under my mt. After installing Scotts' belly pan I saw an increase of 5% on the mpg.
 

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Hi!
I too do the lean burn dance..
(heck the instrument cluster has become a game of optimization of sorts, and I may have to put electrical tape over the graphs for safety :) )

In >my< situation I found 60-65mph in 5th.. my car would slowly droop out of lean burn and wump.. down to the 50mpg mark on the meter and not climb out.. never get back into lean. I could assist it back in, but it would slowly drop out again.

When I run 70-75mph, it can hold lean burn.

I am going to assume the efficiency of the engine prefers 2500 rpm over 2000 rpm and just makes that tiny extra bit of horsepower to maintain steady state lean running..

My .02

:)

Ken
 

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I too do the lean burn dance (heck the instrument cluster has become a game of optimization of sorts, and I may have to put electrical tape over the graphs for safety)....
fyi, you can turn the instantaneous mpg displays off: turn key to position 2, page to the display that you want to turn off, such as Lifetime, Trip A, or segment, press and hold the FCD button...
 

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fyi, you can turn the instantaneous mpg displays off: turn key to position 2, page to the display that you want to turn off, such as Lifetime, Trip A, or segment, press and hold the FCD button...
Can you please elaborate? I'm not sure what you're saying. I toggle all the time between (mostly) Trip B, my MPG for each day, and the FCD (trip segment). Is this what you mean by "turning something off"? Or is there some easter egg where you can eliminate it forever? Or are you talking about the instant MPG bars at the bottom? Once you turn it off how do you get it back?

Sam
 

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I'm talking about the 'instantaneous mpg' bars at the bottom of each trip meter (lifetime, trip, and segment). You can make those disappear. Pretty sure you can do it for each meter. And I think you might have to do it when you first key on... Repeat the process to turn back on...
 

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Wow. Learn something every day. I had them disappear by accident once. When they were gone they were gone for all trip meters. I think I had to disconnect the battery to get them back. Maybe this was caused by something else.

I can't imagine why anybody would not want to see the instantaneous MPG. I felt lost without it.

Sam
 
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