Honda Insight Forum banner

1 - 20 of 48 Posts

·
Registered
Joined
·
817 Posts
Discussion Starter #1
When I first bought my 2000 MT Insight back in April it had an IMA and check engine light on and just under 200k miles on it (50.0 LMPG displayed). During the trip from Georgia to Texas I got about 42-43 MPG. The code was for the motor position (commutation) sensors. In my case the sensors were physically damaged by a spring that had broken loose from the clutch.

A few weeks later, after a new clutch, sensor, sensor plate, master/slave cylinder, and rear engine mount; I was able to get it inspected and transfer the title. I was now able to get about 45-46 MPG combined. The transmission still has common syncro issues, but seems ok aside from that. According to previous owner, the IMA battery was replaced recently with one from Bumblebee. So far it appears to be in good condition.

After making undercarriage panels for the front that were missing, and cleaning out the EGR plate (wasn't really clogged, but not clean) and getting the tire pressure at > 40 psi I was getting closer to about 48-51 MPG combined for a full tank. Recently I've replaced the EGR valve, rotated the tires, and upped them all to 50 psi. cruising at low speeds is a lot better with the new EGR valve and can I can maintain about 53 MPG.. maybe a bit better; I haven't driven much since, but definitely still in the 50s.

The wheels are not stock. The rims are Honda, but they're 15" (maybe for a civic?). The tires are Kumho Solus KH16 175/55R15. These tires are a tad wider and weight about 3 lbs more than the RE92s. I don't know what the rims weigh. They have great grip, but this is obviously not ideal for MPGs.

Possible future improvements related to MPGs:
- clean vtec screen
- more undercarriage panels for the rear
- modify intake for slight "ram air"
- relieve exhaust back-pressure by modifying/replacing cat and/or muffler
- (once they're a bit more worn) investigate tire options
- (when the battery is older) replace the 12V with A123 pouches
- at some point, MIMA

I also have the components for a grid charger (Mike's simple design). I just haven't put them in a case yet. I'm planning on replacing one of the potentiometers with a panel mount one so I can easily vary the float voltage. On occasion I may want to balance the pack, but more frequently I may just want to bring it back up to ~90%. This isn't that useful without a MIMA solution, but pretty easy to to do and I already bought the parts.

I'll post more here as I do any modifications/repairs on my car. It'll be kinda my car's story thread.
 

Attachments

·
Registered
Joined
·
817 Posts
Discussion Starter #2
Today on my way home from work I was actually able to maintain speed at ~54 MPH for minutes with the FCD near the 75 MPG mark. Previously I hadn't been able to do that at any speed for more than a few seconds without getting some hesitation and slowing down. I think I even had the A/C on (econ mode). I haven't done anything to the car since I replaced the EGR valve last week, but I also haven't driven it much since then. Maybe it's taken that long for the ECU to relearn and the valve was significant problem.

I just filled up. I went about 480 miles on that tank. MPGs were 52.6 on the FCD, 50.0 calculated. Most of that tank was before the new EGR. I'll post my next tanks numbers once I have time to go another 500+ miles. I'm guessing it'll be a bit better.
 

·
Moderator
Joined
·
3,641 Posts
Congrats on your car and the improvements! That is really good for non-OEM tires.

But don't forget to calculate the difference in speedo/odo error based on your tire size.

PS: Those look like 05 Civic Special Edition wheels.
 

·
Premium Member
Joined
·
202 Posts
Nice job on reviving this little gem!

Since the words "lean burn" don't appear anywhere in your post, we all recognize that you are just in the early stages of learning to drive this car. Driving in lean burn is the key to taking your fuel economy from merely wonderful up to phenomenal.

In Texas, with higher speed limits, you will often be challenged to spend a lot of time in LB. What you need to do is to learn to recognize when you are in it (I would highly recommend the OBDIIC&C gauge for this), then start working to increase the speed that you can maintain in LB.

The car is extremely sensitive to minor changes when you are trying to maximize speed in lean burn. Those tires and wheels, while not making a huge difference in mpg at 75 mph, will make a huge difference in how fast you can go while maintaining LB.

Your description of a loss of power in the low 50-55 mph range is lean burn cutting in. Being able to run @53 while maintaining 75+ mpg sounds like you are there. You can see that driving in TX at that speed will not be popular. I can regularly maintain 65 mph in LB, which is a little more useful, but I still only average about 63 mpg in TX.

MIMA is great for the control it gives you, but learn the car first before trying to find one. A clutch and brake switch (search here for Calpod switch for more info) will probably give sufficient control and the IMAC&C will probably be a good alternative to the MIMA.

Learn lean burn!
 

·
Registered
Joined
·
817 Posts
Discussion Starter #5 (Edited)
I understand the concept of lean burn, I simply didn't mention it. I'm likely slipping into lean burn when I get that jump up to 75+ MPG on the FCD and from what I can tell, the car doesn't struggle to enter and leave lean burn, but until yesterday I hadn't been able to maintain any speed for any length of time while in lean burn. I have no OBDII monitoring of any sort at the moment, but I will at some point. Once I figure out exactly what I want and have the spare money, I'll likely be ordering some things from Peter.

I was looking at the difference in the tires last night. For purposes of odometer reading, the "revs per mile" spec is probably most relevant. According to tirerack.com, the OEM RE92s have 926 rev/mi and my 175/55R15 KH16 go 919 rev/mi. Not a huge difference, but if my math is correct, this means that my MPGs are really 0.4 MPG better than displayed at 50 MPG.

For my next set of tires, I'm thinking about staying with the Kumho KH16, but going with the smaller 155/60R15 size. As long as my rims aren't wider than 5.5" (I need to identify these rims) they should fit and be a slightly closer match to OEM size and weight. That's a while off though, I've got a bit of tread to get through.

Edit: The rims do look like Honda P/N 08W15-S5D-100B, but I haven't been able to find a width spec
 

·
Registered
Joined
·
1,814 Posts
If you are looking for mileage, put the stock rims and tires (and ONLY the exact size tire, brand, etc) that came with the car. Borrow a set from another member, take it for a spin. The factory tires are probably worth 10 MPG over what you have.
 

·
Super Moderator
Joined
·
4,690 Posts
+1

Those tires/wheels are killing you. The tires weigh 16 lbs, I'm guessing the wheels weigh 20-22 lbs. I just weighed an RE-92 on a stock rim, and it is 24 lbs.

You're spinning 56 lbs of unsprung, rotational weight. That, combined with a non-LRR tire, is HUGE.

Those tires will probably last you a LONG time, which would be a horrible situation to live with. There is no point in trying anything else for good mileage as long as you're driving around on these anchors. Sell them to somebody with a Civic or something and get a set of stock rims and RE-92s. They will make a huge difference.

Sam
 

·
Registered
Joined
·
817 Posts
Discussion Starter #8 (Edited)
Look, I didn't pick the wheels. This is what is on there from the previous owner. If I do keep the rims, I will likely downsize to the KH16 155/60R15 which is only 1 lb heavier than the RE92 sccording to tirerack.com. The weight of the rims is really the wildcard here. I'll probably have to weigh one at some point.

I bought the car to replace my Vespa GTS 250. If I can get near 60mpg I've accomplished my original goal and I think it's better with the new EGR valve. Right now I'm at about ~55 mpg city since I filled up yesterday and it's noticeably easier to maintain a decent SoC in city conditions. Once I'm able to sell my Vespa I can spend a little more on the Insight, but until then I can't.
 

·
Registered
Joined
·
4,005 Posts
This is a topic that's been discussed and tested to death on here. 15" civic rims and ANY tires will probably cost you 7-8mpg city/5mpg highway.

Even other eco tires the same size as the stock tires on stock rims will cost you a significant amount.
 

·
Registered
Joined
·
120 Posts

·
Premium Member
Joined
·
9,658 Posts
"Sorry that wheel is not available for your Honda Insight".

Per the above link.
HTH
Willie
 

·
Super Moderator
Joined
·
4,690 Posts
Not a problem. I don't mean to criticize, I was just trying to help. I know that the wheels came with the car.

Why don't you remove one and weigh it on a bathroom scale. That's what I did with the RE-92. Then compare that with 24 lbs, and multiply by 4. The smaller Kuhmos will save you two pounds/tire. If you're going to keep the wheels (they DO look nice!), you might as well wear out the big ones before replacing them. The smaller ones will be better but still nowhere near an RE-92 on a light rim.

Sam
 

·
Registered
Joined
·
120 Posts
"Sorry that wheel is not available for your Honda Insight".

Per the above link.
HTH
Willie
Yeah, that really annoys me about TireRack. Their wheel fitment guide is riddled with errors. I have seen them recommend wheels that didn't fit, and also not allow you to view ones that obviously do. I believe it is the 6" width and different offset that fool their system, but there have been a few members here who have had them.
 

·
Premium Member
Joined
·
202 Posts
I also was going to comment on some of your proposed mods to help the engine breathe better. This is a HP/performance mod. It likely won't help mpg. The engineers at Honda really did know what they were doing to maximize fuel economy, and nobody has ever come close to their achievements, including Honda.

You can make changes to make the car prettier, but mpg will suffer. You can make changes to make it faster, but mpg will suffer. You can put tires on to make it handle better, but mpg will suffer. It is a delicately engineered balance -- mess with it and you usually suffer.

You kinda have to decide what kind of car you want and define your goals, then work toward that. Replacing the wheels and tires to go stock will probably never make economic sense, but it makes a lot more sense than ANY of the other things on your list of mods. Lots of G1 owners don't care a whit about maximizing mpg and just want to get 40 mpg while looking good and going fast. Maybe that's you. If it is not, then FIND one of those owners. They'd love to trade wheels with you ...
 

·
Registered
Joined
·
817 Posts
Discussion Starter #15
Obviously MPGs are important. It is the reason I bought the car, but performance and handling are also important to me so my goal is to find the best balance and, where possible, improve one of the three without harming another. The best balance for max MPG may have been achieved by the engineers when this car was new, but that's not the current condition it's in and I'll go back to stock when it's the best improvement, but I'm going to investigate other options.

Here's the list I posted earlier and my thought process on each
- clean vtec screen:
unlikely to effect MPG, but can help performance and is important for protecting the engine.

- more undercarriage panels for the rear:
Any improvement to aerodynamics will help efficiency and performance. I may still missing some of the OEM panels near the rear. My home made panels for the front have been a noticeable improvement, probably worth about 6-8 MPG in my estimation at highway speeds.

- modify intake for slight "ram air"
I've read it discussed here and I like this article by Julian Edgar. Any performance or MPG gain it yields is likely to be pretty small, but it's not going to cost me anything and I don't think it would throw the original design off balance.

- relieve exhaust back-pressure by modifying/replacing cat and/or muffler
If we're going for straight performance, the open the better. If we're going for MPGs then somewhere close to OEM amount of back pressure should be good. I'm working under the assumption that the cats, especially if they haven't been replaced, at 200k miles may not be providing the original amount of flow even though I'm not getting a code. It's something worth investigating. Other people have reported MPG increases with muffler deletes. Buying new cats would not make economic sense unless I needed to in order to pass inspection.

- (once they're a bit more worn) investigate tire options
Ok, here's the math for me. On average I can put about 20k/year on a car. At 55 MPG and gas at $3.30 that's $100/month. If that increases to 65 MPG, it's a possible $15/month savings or $180/year. At some point, it's worth it to get the better MPG, but it's also ok economically to let these tires live out their lives and enjoy the handing. If someone wanted to trade me some 14" rims, I would definitely consider that. The future availability of the RE92 is also a factor and I haven't yet experienced the handling with the RE92s.

- (when the battery is older) replace the 12V with A123 pouches
I can't waste the money on it until my current 12V needs replacing, but keeping the DC-DC converter from having to charge the 12V as often can improve efficiency ever so slightly. Also, I use my car as a power source sometimes when I'm camping. If I can get more capacity in the 12V it's convenient for me.

- at some point, MIMA
I already bought the pieces for Mike's simple grid charger. My current plan is to actually build the grid charger into the corner of the IMA bay and have the float voltage adjustable with a knob. Combined with a MIMA solution, I can drain the IMA battery a bit during my commute for better MPG and then charge it back up to ~90% at night. This may cause a bit more cycling of the IMA battery, but I think it will be worth it as long as our electricity stays substantially cheaper than our gasoline.
 

·
Registered
Joined
·
817 Posts
Discussion Starter #16
Not a problem. I don't mean to criticize, I was just trying to help. I know that the wheels came with the car.

Why don't you remove one and weigh it on a bathroom scale. That's what I did with the RE-92. Then compare that with 24 lbs, and multiply by 4. The smaller Kuhmos will save you two pounds/tire. If you're going to keep the wheels (they DO look nice!), you might as well wear out the big ones before replacing them. The smaller ones will be better but still nowhere near an RE-92 on a light rim.

Sam
Yeah, I don't expect the smaller tire size to be as light of a setup as OEM, but it is the available compromise if I don't buy 14" rims. I don't have a bathroom scale, but I may be able to use our shipping scale at work at some point. I'll post results if I ever get around to that.
 

·
Registered
Joined
·
817 Posts
Discussion Starter #17
Those do look pretty light! That would be $500 I don't have at the moment, but they look good. Also they're 6" wide which is the maximum width rim for the RE92s. What's the width of the OEM rim?
 

·
Registered
Joined
·
817 Posts
Discussion Starter #19
I'm planning on updating this thread with my MPG info with each tank I get through.

Tank scenario:
Partly commute along with one round trip to Austin. On the way up to Austin lots of traffic issues and hot. A/C on the whole time. Also, I the car stopped allowing full regen for about the last 20-30 miles up there, but worked fine on the way back (I think my IMA PDU cooling fan may be dying, will make another thread). Also cooler on the way back, partly at night.

FCD readout: 54.9 MPG, 481.2 miles
Gallons used to refill: 9.125
Mileage corrected for tire difference: 484.9
Calculated MPG: 53.1

Other impressions:
towards the end of the tank the car was doing a lot better (better conditions?). I think it could have been closer to 60 MPG under a slightly better senario). I think I was at about 50% SoC at the beginning of the tank, but at about 90% SoC at the end.
 

·
Premium Member
Joined
·
202 Posts
One thing that might help is to disable the heater air vent by unplugging it. The car controls temperature by adding heat even with the a/c compressor running. The a/c and heater work against each other, causing the compressor to run more than needed. It does this to help reduce humidity to defog the windows in cool weather or some such nonsense that Texans don't understand...

Anyway, the procedure is to turn on your a/c and turn the temp setting to 60, which closes the heat air valve. On the passenger side below the dash on the duct is a green plug. Unplug it and the heat air valve will stay closed, no matter what temp you set.

Obviously the heater won't work like this and window defogging is limited. Just plug it back in if you need those functions.

Realize that this car is different and the compressor makes a tremendous difference in both performance and fuel economy. If I recall correctly it only takes about 11hp to push the car at a decent speed and the compressor takes about 5 HP. I don't remember the exact numbers.
 
1 - 20 of 48 Posts
About this Discussion
47 Replies
17 Participants
johnnyviri
Honda Insight Forum
We’re the ultimate Honda Insight forum to talk about Honda’s hybrid car and its fuel economy and specs!
Full Forum Listing
Top