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so i keep seeing various posts and replies of people getting around 60-70 mpg traveling at speeds of 70-80 mph. for the life of me, i can achieve nothing of the sort compared to there stats. going 70 i get between 50-55, at 80 i get nothing more than 50, typically around 45. around town, i get somewhere in the range of 65-70 mpg on a tank. this is also a slight concern due to so many individuals getting much better around town results, then again Tallahassee does have a few hills. typically my average driving speed is around 40 mph. i can see when my car enters lean burn reaching around110 mpg instant, what else can possibly be making my mpg so much more different.

now im looking for answers not including the driver as the issue. on the highway, i hold the pedal only enough to keep the speed constant, does not seem to enter into LB, no boost of instant mpg after reaching cruising speeds.

around town, im a snail. 1st takes me up to 6-9 mph, 2nd-to about 16mph 3rd- til 30-32 mph 4th- til 38-40mph and 5th there out, and this is my acceleration schedule if you will, not cruising. if im cruising in a neighborhood, you can find me in 4th gear going 25 mph. in general i keep the RPM's low and have the IMA crawl me up to speed.

also, IMA battery is in fairly good condition, does not throw me codes anymore, stays in the upper half of its charge range, and is conditioned very regularly for max performance and to prolong its funeral.

if you guys have any idea what may be wrong with my car please let me know! im stumped! THANKS!
 

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I've owned two mt insights, and both behaved almost identically.

The highest speed I can trip average 70 mpg is around 63-64 mph.

Instantaneously, you can do better, but average for the trip? No. Not unless there's some magic sauce I don't know of.
 

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Try to keep the rpm around 2500 rpm in 3rd, 4th, or 5th gear, Not 1st or 2nd.
To get into LEAN BURN, accelerate to slightly above the desired speed, hold for a sec. then back off slightly on the throttle until you see the FCD jump up and it maintains that position on the FCD bar. IF you have the OBDIIC&C gauge the green light will come on. Without the gauge, it just takes patience and practice to "Get the Feel" of lean burn.

You should be able to maintain 45mph in 3rd with LEAN BURN.(Level Ground)
(My experience)
HTH
Willie
 

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I have a few suggestions, though I'm not sure they will improve your MPG very much. First, If you encounter hills, try to let the car lose a little speed as you climb so that the car can stay in lean burn. Then gain the speed back on downhill to maintain your average. Second, if your engine tune isn't perfect, you may be down on power a bit - plugs, timing, injectors, coils or maybe even a low flow catalytic. This will cause the car to achieve less LB.

Lots of folks use slightly higher air pressure to lower rolling resistance. It can be significant. Last, use a very steady accelerator application.

In general, I think 70MPG at 65MPH is pretty close to best you'll get. Some of these cars may have aero improvements and that makes a big improvement at high speed.
 

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My first reaction is to call BS at numbers like that. Aero drag at 80mph is 51% higher than aero drag at 65mph. I don't think one could even enter lean burn at that speed due to the higher load.

'course, I know squat. I just putz around in the comparatively massive HCH2... :)
 

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SK
Thanks, finally someone mentioned load.

Willie
 

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Cameron,

Next time you come through Lakeland PM me and I'll show you how I do it in person. Been dying to show off the car to somebody anyway!

Since we pretty much drive the same roads, anything I do should also relate to your commute.
 

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you won't get those numbers from a stock insight, if you mod the car to act better while in lean burn then you can push the numbers higher.

what most around here don't mention is that lean burn runs smoother and generates more power if you retain heat in the engine. ie the coolant and intake charges are hotter. if the car cools off then you won't be able to lean burn at 70+mph, you also won't be able to with a stock insight either, i fall out of lean burn at about 65mph on a nice flat road(a flat road where your mpg and speed result in the same figures in both directions on the same stretch of road).

in some cases you may have a road with a long downhill grade and able to lean burn and do it at higher speeds. in other cases you may have a gradual incline and struggle to keep lean burn at 55mph. the road may appear completely flat!

heading south in wisconsin i was going downhill but the car acted as if i was climbing a constant hill for 100 miles. once i passed through that stretch and was near st louis i could lean burn at 100mpg at 70mph for 10 mile stretches at a time in what looked like uphill inclines. so also don't listen to everything everyone tells you, some things are situational.


i just drove from north dakota down here to lakeland and managed 70mpg but my average speeds were around 63mph, but i haven't touched anything on the car as far as mods go aside from 50psi in the tires. if i tried to go any faster it would drop out of lean burn and lose a chunk larger in fuel mileage in sacrifice for mph so that is strictly on the ragged edge of lean burn in my '00 with 250k miles.

for the last leg of my trip i gave in and set my target speed to 73mph and the net result was 54mpg from 70mpg at 63mph for reference.

i did actually manage to get 83mpg after i left fargo north dakota for about 200 miles while doing about 63-65mph, then it sank like a rock once i hit the hills.
 

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what most around here don't mention is that lean burn runs smoother and generates more power if you retain heat in the engine. ie the coolant and intake charges are hotter.
Whoops, found out;)
 

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Whoops, found out;)
i know heat mods are mentioned all over but the correlation isn't always defined. the car bucks when it's cold and hates lean burn, i actually began to think the car was problematic but if i drove it further than 10 miles or on really hot days then the lean burn would smooth out and work better.

course i learned a lot driving the car across the country this last week. while driving it locally it wasn't very productive while in lean burn so emphasis being put on warming it up quicker.

i chose to ignore the mods at first because the car already trips the fans and runs about 200F with a 106F intake charge, which is borderline what the car tends to prefer. lean burn treating that as a cool temperature.
 

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A healthy insight would get easily in lean burn on the Highway at speeds under ~75. easily I mean every time you ease off the throttle and it gets to a TPS of 19-21 (according to my scan gouge II) . Whether you do it on purpose or by accident.
some of the factors that i know of that may put extra load on the engine and thus prevent lean burn are:
- deteriorating IMA battery
- bad 12 v battery
- wrong tires
- under inflated tires (under 45 psi)
- clogged egr plate
- bad egr valve
- bad LAF and/or O2 sensors (these may not be bad enough to throw a code but still deprive you of lean burn)
- missing under body panels

- bad a/c clutch
- using a/c

and probably many others I do not know of yet....
 

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i chose to ignore the mods at first because the car already trips the fans and runs about 200F with a 106F intake charge, which is borderline what the car tends to prefer. lean burn treating that as a cool temperature.
You can get the coolant temperature into the 210F+/- sweet spot if you block all the grill openings except for a 3X7 slot right in front of the radiator. Then get the IAT into the 200+ range by using an air pick up hose around the right side of engine and back to the catalytic converter. Of course, you won't be able to use the A/C:(

As always, recommend you have something other than the dash gauge to closely monitor coolant temp. accurately.
 

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My first reaction is to call BS at numbers like that. Aero drag at 80mph is 51% higher than aero drag at 65mph. I don't think one could even enter lean burn at that speed due to the higher load.

'course, I know squat. I just putz around in the comparatively massive HCH2... :)
Oh...

68-71mph, light traffic, to work and back.
 

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Lol, I let that one slide since not everybody lives in a hot, completely flat area like me and Cameron do.

I'm a day and a half into this new tank and reading over 74 mpg on the FCD. I drive the highway at 70 mph every day and put
about 300 miles a week on the car, and I haven't had a tank dip under 70 mpg in months. It's harder now that I use the AC pretty
much every night on the way home, but still do-able
 

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69.5 average ain't 80.

80mph vs. 69.5mph is an increase in aerodynamic drag of 32.5%

69.5 vs. 65 is only a 14.3% increase.

The point I was trying to make is that significant speed increases at highway speeds can have a major increase in drag. I would
call your numbers "close" to the more typical 65mph cruise speeds. Even my bulky HCH2 can do mid to high 50s at 62-65mph on
straight and level. When I start to push north of 70, mileage starts to drop. At 75, low to mid 40s is great.
 

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You can get the coolant temperature into the 210F+/- sweet spot if you block all the grill openings except for
a 3X7 slot right in front of the radiator. Then get the IAT into the 200+ range by using an air pick up hose around the right side of
engine and back to the catalytic converter. Of course, you won't be able to use the A/C:(

As always, recommend you have something other than the dash gauge to closely monitor coolant temp. accurately.
what is the improvement in doing so, is there any risks to consider. i probably wont pursue this method YET because i still need a OBD
gauge, but definitely a consideration.
 

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cowmeat, id love to come see your insight and have you show off your moves. ill be heading back that way August 7th after classes
are over, PM me and well figure it out, ive been looking for someone who i can share the same love and interest of the gen 1 insight
as myself, haaha
 

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thanks to all of you for the responses!!! especially Lyger, i appreciate the time and thought you put into your response. i think you
have an excellent point of the speed and heat issue with LB, this issue makes more sense to me now if im going 70+ and cooling the
engine a lot more than around town cruising speeds when LB is frequent.

this being said it seems heat mods are the biggest thing to explore at the moment. im just a little nervous since i know how much our
engines love too much heat, just had the head warp
after a bad head gasket. one re-do is enough.


Jime, you had mentioned a modified radiator shield. what kind of result do you see with this mod? Pros? cons? can this be combined
with a hot air intake or would that be too much heat for
the engine. i have heard of the people doing hot air intakes but never understood why, this makes sense though. is it true that
the hot air intake makes the car loose some power? if so, is it
still worth it? or is this simply a symptom of all heat modifications?

by the way, tires are at the max wall pressure (52), have all the underbody panels, new plugs, clean EGR plate, EGR valve didnt look
clogged at all when removed so i assume its ok, i run chevron
techron fuel treatment every 3k miles when i do the oil, and primarily only fill up at chevron stations with the techron added in the
gas, so i dont feel its injectors. and as for AC, i dont run it if i
can help it, and the only time i really cant is when the lady is in the car complaining. happy wife, happy life. but regardless cowmeat,
(i think is who said this) i really have no clue how you achieve
anything in the midst of 70mpg with AC, this blows me away.

also SK also has a point with BS, not everyone does i know but yeah, i guess some people need it to fuel there ego, good for them.
thanks guys look forward to hearing from you!!

cheers!
 

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The typical problem that develops with the OEM EGR valve is an issue with internal swiper. You can't see it without taking the thing
apart. However, if you're not throwing codes or experiencing bucking, the valve may be fine.

I have yet to drive an unmodified insight in perfect condition. My #1, currently broken, was performing pretty well aside from it's
catalytic converter issue. The best MPG numbers I saw with it were while it had a big crack in the catalytic converter and was thus
running a more open exhaust. At that time, I was getting almost 70 MPG tank averages and could maintain lean burn at up to maybe
70 MPH on the highway, level, no wind, no intentional drafting. Staying in lean burn at over 70 MPH is significantly more difficult in my
opinion, but you can get there with ideal conditions, some good drafting, and/or significant modification to the car (like a turbo, full
underbody smoothing, or a tail if you can make one that won't fly off at those speeds).
 

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i wonder how open exhaust would impact lean burn. *coughs*

:evil:


sure it could aid in the engine retaining heat but there is quickly a point of diminishing returns. i know plenty about semi plugged cats
and how engines react to them.

but anyways, yeah. i'll call BS on claims of anywhere near 70mpg at 80mph, i have to really push mine to get to 80 and i'm wayyyy
out of lean burn at that point. 70+mpg at 70mpg, possible, but once you get to 80mph this little car feels like it's trying to take off
from the road and your foot is half mashing the pedal for the attempt. i've coasted up to 80 before at 100+mpg on the FCD, but
that was a huge downhill...


and then again some people just get lucky with a combination of things on their car, the ECM and BCM also apparently can have
a large impact on mpg.
 
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