Convert USA Corolla 7A-FE to lean burn?

[ps2fixer]

@Honda100

Thanks for the info, I figured the ratings were a bit closer than that... I have to beat the hell out of my corolla to get 33mpg. I still don't really understand what is so special about my car that gets me into the 40mpg range, most of the other corolla owners can't get near 40mpg without pretty heavy mods. My personal best trip is around 55mpg @ 45mph for around 38 miles. My worst was when I first bought the car, 33mpg I think and it needed an alignment BADLY, rear struts completely blown out (lots of wheel hopping), all 4 tires shot, front end beat up with missing marker lights, etc, and I was driving it at 75-80mph following my dad.


@Sven7

I have came across similar things for getting a diesel engine to swap into a Camry. Sadly, it costs $4k+ just for the front half of the car, the entire car as it sits might be worth $1000-1500 lol. If I had more money than brains, that would be the way to do it, but I try to think things out logicly. A boat tail and a couple other small mods *should* get me to the 50-60mpg range, I'm just being lazy about doing it.









About a month ago my check engine light came on, and when I checked it, it said the cat was being inefficient (5% tolerance). Drove the car "normal" for a couple of weeks and the code cleared itself, not really sure what happened there, maybe the O2 is going bad, and I'm already running lean somehow?

[Sven7]

Or you could buy a Civic

[RobbMeeX]

Quick reply:
5afe
Megasquirt
And you would be trying this stuff as I am going to sell my 7afe Celica

[Honda100]

About your mileage, I have a story. I had a Toyota Windom (Lexus ES300) which was rated for about 22 mpg us and I averaged about 19. The mass air flow sensor was bad, so I bought a cheap auto part store version to replace it. From that day on, the car never dipped below 25 mpg and I even managed 39 on the highway. Just out of curiosity I pulled plugs and discovered that it was running on the lean side (quite lean) but still within safe limits. So, in short, you may already have a lean burn Corolla unknowingly.

[ps2fixer]

Megasquirt sounds really interesting, I'll have to read up on it more


EDIT @ Honda100

I'm kind of suspecting something along them lines. My MAP sensor display on my scan gauge seems to be a little "jumpy" for the numbers. Like when it is warmer out I can steady drive at around 6.3-6.9, if it touch 7.0 at all, it basically instantly jumps to 7.5-7.9, I have never seen it read like 7.2. After the 7.5-7.9 range, it seems to jump to around 8.5ish which is what I'm running at currently at steady speed for ~40mpg. I think with some areo mods I could get it to stick in the 6.x range and if I keep it in that range, I can get up to 55mpg with the rest of my trip's stops and goes. It is really odd, even in the warm months, if I don't really watch it, or use CC it is always around 7.5-7.7 to maintain steady speed (45-50mph).

Another thing to note, the timing advance DROPS when it is in the 6.x range, steady driving is normally at 37-39 and when it goes into the 6.x mode it is around 26.

I don't remember why exactly, but my dad needed to pull the distributor of, or adjust the timing. What ever the reason way, when he put it back on, he put it on all the way advanced and I remember him wanting it to advance more to be "proper", I don't remember how he was determining this though. Maybe I should adjust it back slightly and see what effect it has, just would hate to drop down to the 30s >.<

[ps2fixer]

Got 43mpg on the trip to work (night time, below freezing), I found the "hidden mpg mode" again. Maybe this car has the same ecu/logic as the lean burn models overseas. Basically to get into the mode, I have to do 2 steps...

Speed up to ~50mph so I have time/speed to loose adjusting to get into the mode
Let off the gas to a 5.x reading for the map sensor (timing drops from 39 to 26)
Lightly press on the gas and target 6.6 map reading (keeping the timing at 26)

If I go above 6.9, it instantly jumps to 7.9... and the timing jumps back to 37-39.

I have a couple of DVR video recorders comming in the mail, so maybe my first video I will show what exactly is going on hopefully learn what is really happening. My guess is either a lean burn mode, or a spark knock is detected @ the lower map readings and it pulls back the timing for that range and the maybe the map sensor is bad/sticky. What ever it is, I'm going to try to stay in that mode again more often, been a long time since I really tried, but the resulting mpg is much higher per trip (upto 50-55mpg in summer).

[cujet]

While this may not apply to your project, to reliably run "lean of peak", you will need a wideband sensor. Then, you will need to program in a specific set of conditions under which the engine will be operated lean. Also, you will likely want more timing advance, as a lean mixture burns more slowly.

To really get this right, a stand alone engine management systems needs to be used, with the wideband, and someone who knows tuning well enough to do it correctly.

Many modern stand alone systems will autotune, when properly programmed.