Poor MPG - willing to spend to fix

[interestedguy]

I just bought a 2000 manual Insight with 165K miles. Its lifetime is only 42 MPG. I have been driving as gentle am possible but it is only showing 44 MPG for the current tank. From all the threads I have read that is impossibly low.

Problems I know of:
1) Tires, they are worn out and a brand i have never heard off, I have a set of OEM tires on order
2) Underbody panels, they are gone
3) IMA battery seems pretty weak, if I do full throttle it will only give full boost for 1-3 seconds then a few bars for awhile after that and has re-calibrated a few times.

I am an engineer and I bought this car because I love the lengths they went to to save weight. I am willing to spend some real money, including replacing the IMA battery if necessary, but I don't want to pour money in only not to get results. Any thoughts on what I should attack would be appreciated. From other threads maybe I need new spark plugs or to clean the EGR, I just have no idea what could leave me 20 MPG out of the hunt. Thanks

[Willie Williford]

Worn tires are your biggest obstacle. New ones will DEFINATELY help. Up the tire pressure to 50psi.Try to drive without useing excesive IMA assist. Sounds like your IMA battery is on the way out. Underpanels will help your mileage above say roughly 45mph.
There are numerous threads about how to drive on this site.
Learn to drive with an "egg" under the gas pedal. , coast whenever possible.
HTH
Willie

[Jivko57]

a few things that probably will help:
-a grid charger to keep the ima battery in better shape
- cleaning the egr plate
- check the 2 ground straps in the engine compartment and replace if broken
- try to stay in "lean burn" more
-mileage depends a lot on amount of "city" driving vs "highway"
- using A/C kills the mpg

[uhtrinity]

Also check the air filter, that can have a pronounced effect as well. On the tires, you don't mention if these are the Potenzas or some or brand. Tires can also make a huge difference.

[interestedguy]

I don't really feel safe running the tires at 50psi, I am running 42 to stay within the tires max on a hot day, that may be costing me a few MPG but I wouldn't think it would be more than that.

The current tires seem like they must but some auto parts place store brand as I heard of all the major brands. I have a set of the proper Bridgestone Potenza RE92s on order from Costco ($400 for all 4 installed) they should be in next week.

I seem to have trouble keeping it in lean burn mode, it will seemingly slip out without my foot having moved at all. I do notice the battery charging while I am under power (not slowing down) sometimes but I have never seen a error light come on at all.

I don't really want to get into grid charging, I want to see how far I can go with the closed system, is grid charging what everybody who is in the 70MPG plus range is using?

Where is the second grounding strap in the engine bay? I only know of the one, part number 32600-S3Y-A00 009 001 CABLE ASSY., BATTERY GROUND

I will take the EGR and the EGR plate apart and clean it.

I do need to change the air filter, I wouldn't say the current one is awful, its funny but i can't find them at any local auto parts places, i will get it online.

Thank you for your time

[Right Lane Cruiser]

The max sidewall listed pressure is measured cold. Don't worry about heat induced pressure rises.

The tires adding excessive drag could easily make attaining and retaining lean burn difficult.

Grid charging has been suggested because older batteries often suffer from cell imbalances that the car electronics were not designed to correct. A nice long, low current charge can get the all cells "top balanced" and return the battery to better performance more closely approximating "as new" condition (ie, better capacity and better output). It is emphatically not necessary for 70+mpg performance. I've spent several years turning in tank averages over 100mpg (in warm weather) without a grid charger and without MIMA (manual control of the IMA system). If you are curious, the key is to avoid use of the battery -- even though that might seem counterintuitive (it takes more energy to replace used charge than if you had never used electric assist in the first place).

You are going to really enjoy your vehicle once you've worked through the current issues!

[02insight]

you should be able to get at least 60-65mpg out of a stock insight (stock tire pressure etc..) and driving it easy (55mph highway + A/C off). After all, that is what they were rated for. (hwy)

I would not apply mods (50psi tire pressure), to try to overcome bad mpgs, because by doing that, you are not really fixing the problem, just covering it. So I would try to find the problem first and get a good running stock insight that can do atleast 60mpg, then try mods such as radiator block, high PSI in tires, clutch switch etc...

by your description, your battery seems kinda bad. Is it doing a forced charge a lot of the time? Also check for other things that may be putting drag on the car (brakes, correct engine oil, transmission oil, aero covers)

[interestedguy]

I have seen a fair bit of forced charging. I just changed the oil to mobil 1 0w-20 with a mobil 1 filter. I also changed the front brakes and rotors, I don't think it is a mechanical drag issue with the rear brakes or bearings because in neutral with the parking brake off I can push the car with 2 fingers on each hand, i was shocked by that.

All the underbody aero panels are gone, I have been on majestic's website but I am having trouble finding the panels I need.

[uhtrinity]

I suspect you will see a huge difference just in using the correct tires. A friend bought an Insight a year ago and I drove is back for him over roughly 150 miles. The best I could get out of the car was ~55 mpg over the trip. As soon as he repaced the non oem tires with Bridgestone Potenza RE92's the mileage went up to 65 mpg. After replacing the air filter is went up above 70.

The car is comprised of so many little features that increase mileage, on the flip side if any of those features get compromised you will see a mpg drop.

[retepsnikrep]

Handbrake cables also seize up causing rear brakes to drag. jack it up and check they should spin very freely.

Front brakes can also drag more if not serviced and lubricated they don't spin as freely anyway due to gearbox etc.

I also concur with the rest of the advice especially tyres/pressures and grid charging.