Lean Burn all the way!

[steffen707]

Originally Posted by brucepick

Eureka. HX Lean Burn apparently requires 2400+ RPM

That's odd, in the VX it has to be under like 2400 or 2800, not OVER. Is this right?

[steffen707]

Originally Posted by phord

Lean burn all the way? Not. I had Chrysler lean burn car and embarrassing experience with it until I swapped nonfeedback carb and distributor with vacuum advance it it. Lean burn all the way? ------------Noooooooooooooooooooooooo.

Okay.....lean burn honda FTW! not chrysler.

[basjoos]

Originally Posted by steffen707

That's odd, in the VX it has to be under like 2400 or 2800, not OVER. Is this right?

In my car, once the normal operating temp has been reached, lean burn is strictly dependent on the manifold vacuum pressure, not the RPM or when VTEC kicks in. It can cruise along in lean burn at 90+mph at over 3000rpm with VTEC engaged. With the SuperMID it is very easy to tell when you are in lean burn.

[steffen707]

Originally Posted by basjoos

In my car, once the normal operating temp has been reached, lean burn is strictly dependent on the manifold vacuum pressure, not the RPM or when VTEC kicks in. It can cruise along in lean burn at 90+mph at over 3000rpm with VTEC engaged. With the SuperMID it is very easy to tell when you are in lean burn.

neat, how does the supermid show you lean burn? I thought most people had to use a wideband meter to know that.

Isn't the supermid pretty much the same as the mpguino? I just know when i'm in lean burn because i'm getting above 50mpg while cruising, and then if i step on the gas a little too much it drops to 36mph.

[greasemonkee]

Originally Posted by basjoos

In my car, once the normal operating temp has been reached, lean burn is strictly dependent on the manifold vacuum pressure, not the RPM or when VTEC kicks in. It can cruise along in lean burn at 90+mph at over 3000rpm with VTEC engaged. With the SuperMID it is very easy to tell when you are in lean burn.

Mike, this is interesting. Do you remember what ecu revision you have? P07-XXX? Mine is the A01 and:

2400 rpm is the cut for 4 in.hg.
2500 rpm is the cut for 6 in.hg.
2600 rpm is the cut for 8 in.hg.

2600 seems to be the upper limit and vtec engages regardless of load, after this point leanburn will not function at all. Leanburn only operates in 3 valve mode with this ecu.

The table is approximate, but close from what I've monitored with the Innovate LC-1.

Since the decrease in manifold pressure is required for leanburn operation as rpm increases, my gut tells me the actual HP produced is a constant as efficiency decreases with rpm.

[basjoos]

Originally Posted by steffen707

neat, how does the supermid show you lean burn? I thought most people had to use a wideband meter to know that.

Isn't the supermid pretty much the same as the mpguino? I just know when i'm in lean burn because i'm getting above 50mpg while cruising, and then if i step on the gas a little too much it drops to 36mph.

The supermid displays injector pulsewidth and you can see it suddenly drop or rise about 2 usec (independent of changes in throttle position) as it enters or leaves lean burn. Max lean burn pulsewidth is 5.9 on a 90 F degree day and 6.3 when it in the 20's F. As you push the throttle beyond that limit, it suddenly rises into the 7's as it leaves lean burn.

The supermid has a lot more display outputs than the mpguino. Simultaneously it displays the current pulsewidth, current mileage (l/100km), mileage over the last 5 km, total mileage, mileage with the engine running, % of distance with the engine off, total fuel used, total distance, and some timers. Then this display is duplicated fivefold so you set it up for multiple users or driving scenarios. It was originally designed to be used on the Prius, but can be used on any 4 cylinder car with injector and speedometer pulse train inputs.

[basjoos]

Originally Posted by greasemonkee

Mike, this is interesting. Do you remember what ecu revision you have? P07-XXX? Mine is the A01 and:
.

I'm not sure which version I have (I'll need to go out to the car and pull the cover off to see). It came from a lean burn Civic in Ireland, so its whatever version they use over there.

[greasemonkee]

Ahhh, yes, Ireland! perhaps they weren't so emissions restricted? If you find out the code I may be compelled to find one myself, so you may be able to achieve more than 20 hp according to what you're saying.

[chrisoverson]

I'd like to comment on the knock sensor statement. It may well be true on the lean burn honda engine that ignition timing will not be advanced, but that is not true on all engines. The Suburu Impreza for one will certainly adjust timing for higher octane fuels, and so will many others due to the knock sensor.

My particular model car does not have a knock sensor, but I've read carefully through the full documentation for the ECU system including how models with a knock sensor behave. They work by slowly advancing the timing (in this vehicle's case) 0.3 degrees at a time, then once engine knock is detected they immediately back off the timing by 0.3 degrees at a time until knock ceases. Then the cycle starts again.

In this way the ECU keeps the most advanced timing possible, giving the best performance results. My car does not do this therefore higher octane fuel will do nothing at all without a remap, but some cars definately can take advantage of it.

If I may ask, does anybody know the air-fuel ratio used during lean-burn mode? If normal is 14.7:1 what does the honda engine use under this mode...

I'd like to set up something similar on my car during cruising if possible.

[steffen707]

Originally Posted by greasemonkee

Ahhh, yes, Ireland! perhaps they weren't so emissions restricted? If you find out the code I may be compelled to find one myself, so you may be able to achieve more than 20 hp according to what you're saying.

Are the JDM ecu's more lean burn agressive than the us 49 state ones? I too would like to know if the ireland one is more agressive.

I'm going to ireland this fall for my honeymoon. Do they have pick and pulls there? I'm sure the wifey would love that.