I'm still getting bad mileage after tune-up.

[vmirjamali]

I've been getting an avg of 53 mpg round trip 50 miles to my college and back. I've so far changed sparks, cleaned the throttle body, the map sensor, egr valve, changed oil with the best amsoil synthetic, ran seafoam through brake booster, used the techron fuel system cleaner, and lucas fuel system cleaner.

I've done some other stuff just need to remember. So far I'm just getting 53.5 mpg and getting into lean burn is much harder then I though even with a light foot all the time. Running the tires at 42 psi all around as well. Any ideas?

I have a 2000 manual insight.

[Eli]

Most likely it's just your environmental conditions.

Is this on the highway? What speed? Where do you live?

[vmirjamali]

This is mix of city/highway. On highway I get 58-60 or so. Weather now in san diego is 78 degrees, speed is pretty slow too be honest, but it depends. I keep speed limit at all points of time, meaning 65-70 highway most the time.

My battery is weak, do you think that's the cause?

[02insight]

are you sure you are getting lean burn? recently my primary a/f sensor went bad, so I have not been getting any lean burn, and have been getting mpg similar to yours. (55-60mpg)

The way I tell if I get lean burn is if when the mpg bar sorta sticks to around 75mpg even when you are pushing the throttle, and when you push it too far, it falls out of lean burn and goes to 50mpg.

at the moment, with my bad o2 sensor, it seems like it does leanburn, but I dont think it really is, because when you let off the throttle a little the bar does go above 100mpg, but when you re-apply some throttle while the bar is going down, it doesnt hang at 75-80mpg, but instead just goes smoothly all the way down to 50mpg.

but your speeds are a little high. For going 65-70mph, I'd say around 60-65mpg is normal. For driving 55-60mph, I usually see 75mpg.

[vmirjamali]

I actually have had times in the last 1k miles where i've hung around in the 75 mpg or 100 mpg zones for a good 2-3 minutes. Does that mean my 02 sensor and fuel/air sensors are working or do you think that's the issue? I thought that may be the issue so i cleaned the o2 sensor a bit, but it didn't do much. Note though when i let go of the peddle and then press on the gas it immediately drops out of lean and goes down quite a bit to like 45-55 range.

[Willie Williford]

Sounds and acts like "lean burn" is normal to me. Where in SD are you at? Terrain will have a hugh impact. What routes are you taking to college and back.
Would you like to get a few SD? Insighters together for a comparasion run?

Willie

[Jivko57]

weak battery may cause your car to recharge at all times, at this speed and bad battery I was getting similar mileage.. With grid charging at nights and slowing down to-50-55 miles on the Highway I get ~75mpg.

[vmirjamali]

You know what it may be my battery. I'm building a grid charger together, and it should be done tommorrow, when i first bought my car and used a normal 12v charger (it charged the 12v and insight's ima battery at the same time oddly) I got 75 mpg, which is odd, since I haven't been able to get that since the charge I'll keep you updated!

Btw I'm located near poway, ca. My routes are mostly the I-15 down to downtown and back.

[Eli]

It sounds like it may be your battery, yeah.

Unless your engine is throwing codes, I wouldn't worry about things much since you've taken care of the basics. It would tell you if your O2 sensors were on their way out.

[Willie Williford]

Vmir;
Then you've got at least 6 long grades to pull (there and back) so your avg. mpg is about right.
Don't think the 12V charger can charge both batteries at the same time.?

HTH
Willie