Civic HX Lean Burn "Econo" Light

[RPM]

If it makes you feel better the ECONO light is not that useful. In my car it is basically always on when driving sensibly (not even hypermiling).

[firehawk618]

Originally Posted by RPM

If it makes you feel better the ECONO light is not that useful. In my car it is basically always on when driving sensibly (not even hypermiling).

Oh really? I thought it was basically an indicator to tell you when you're in leanburn.

Is it more like a light that comes on under low load indicating economy?

Kind of like the upshift light comes on under low load....

[RPM]

I do believe that it is a lean burn indicator. It's just that you're in lean burn all the time, unless you are almost flooring it or exceeding the lean burn rev limit. An AFR gauge would be more useful because being in learn burn doesn't necessarily mean you are using the leanest possible mixture the motor is capable of (21:1?), i.e. 16:1 is still lean burn.
To maximize FE in my car you have to interpret the subtle changes in the accelerator's response in order to use the leanest possible mixture for the current driving conditions.

[Chrysler kid]

Originally Posted by RPM

I do believe that it is a lean burn indicator. It's just that you're in lean burn all the time, unless you are almost flooring it or exceeding the lean burn rev limit. An AFR gauge would be more useful because being in learn burn doesn't necessarily mean you are using the leanest possible mixture the motor is capable of (21:1?), i.e. 16:1 is still lean burn.
To maximize FE in my car you have to interpret the subtle changes in the accelerator's response in order to use the leanest possible mixture for the current driving conditions.

The d15b is in 3 valve operation most of the time under light throttle which is what the eco light indicates. Under the right throttle and rpm settings the car will enter lean burn like you're talking about

Most of what I read about pin 30 was from the D15 swap ecu and thread

The d15b is a great little motor, it was the culmination of the 10 year development cycle of the 1.5 liter motor they originally set out to create as a model of effecient and power. It also uses only narrow band 4 wire sensors instead of the expensive 5 band on our us spec 1.6


Our us spec hx models only drop into 3 valve operation at higher vehicle speed with lean burn mode

[RPM]

The D15B wasn't sold in Europe, we got the D15Z6, a 2-stage VTEC-E engine with 115 hp, which is what I have. I think you're right about the indicator, it indicates 12 valve mode, which may or may not run very lean, depending on conditions.

[Chrysler kid]

Originally Posted by RPM

The D15B wasn't sold in Europe, we got the D15Z6, a 2-stage VTEC-E engine with 115 hp, which is what I have. I think you're right about the indicator, it indicates 12 valve mode, which may or may not run very lean, depending on conditions.

I learn something new every day

Do you have a build thread for your vehicle with pictures and all that good stuff? I'd very much like to learn more about it

[RPM]

Since the car doesn't really have many (or any) ecomods, I never opened up a thread. If there's interest I can though, as it is something slightly different from what you got in the US.

[firehawk618]

I am really interested in that engine. I would seriously swap one in IF I could get the correct ecu.

From what I understand it would never pass obdii emissions testing in the united states but I am not positive.

Chryslerkid, I was under the impression our engines "y5" operates in 3 valve mode upto ~2800 rpm's then will go into 16 valve operation if you're heavy on the throttle.

Otherwise it stays in 12v generally.

Again, this is only what I have read and so far it seems like the y5 ecu operation is a ton of speculation and very little fact.

I wonder if the official Honda manual for the y5 publishes the ecu's logic for troubleshooting?

If you guys want I will wire in a temporary indicator to my vtec solenoid and report exactly how it operates on my car......

EDIT: If someone is good at arduino code and can edit the mpguino code to add 1 or 2 inputs........I would wire the vtec + upshift to that vs the dash lights.

I ended up pulling my upshift light out. Very annoying! Especially when it's occupying a full light therefore bright vs the real upshift arrow which is mostly blacked out. The other issue with that light is if you follow it there are times that will keep you out of LB. I ignored it and was able to get LB as low as 28 mph and the whole time the ECU was suggesting an upshift which would have kicked out LB for sure.

[Chrysler kid]

Originally Posted by firehawk618

I am really interested in that engine. I would seriously swap one in IF I could get the correct ecu.

From what I understand it would never pass obdii emissions testing in the united states but I am not positive.

Chryslerkid, I was under the impression our engines "y5" operates in 3 valve mode upto ~2800 rpm's then will go into 16 valve operation if you're heavy on the throttle.

Otherwise it stays in 12v generally.

Again, this is only what I have read and so far it seems like the y5 ecu operation is a ton of speculation and very little fact.

I wonder if the official Honda manual for the y5 publishes the ecu's logic for troubleshooting?

If you guys want I will wire in a temporary indicator to my vtec solenoid and report exactly how it operates on my car......

EDIT: If someone is good at arduino code and can edit the mpguino code to add 1 or 2 inputs........I would wire the vtec + upshift to that vs the dash lights.

I ended up pulling my upshift light out. Very annoying! Especially when it's occupying a full light therefore bright vs the real upshift arrow which is mostly blacked out. The other issue with that light is if you follow it there are times that will keep you out of LB. I ignored it and was able to get LB as low as 28 mph and the whole time the ECU was suggesting an upshift which would have kicked out LB for sure.

You're reading voltage under 1v aat the secondary oxygen sensor to determine lean burn correct?

As far as 3 valve operation on the y5 I have no idea, the upshift light could be saying when the car is out of 3v operation for all I know. Vtec engages when the car is in 4v (16v) mode and opens the valves at a more agressive duration than normal.

It would be great to find the actual honda ecu program schematics and protocols however honda created these cars during a time when gasoline prices were very low and as a result the class leading gas mileage was an after though to selling mass produced vehicles that already were very fuel effecient.

Vtec on the hx is triggered at a higher rpm than the ex model, and I do know the vx would use 3v mode in all gears but honda received complaints about the abrupt change from 3v into 4v into vtec. So I assume 3v mode in the hx is only in lean burn conditions to make the car more friendly to drive in lower gears without the abrupt changes in the power band

I spent a few nights reading up about the man who engineered "lean burn" but I can not recall any spefic functions or features besides creating a swirling effect by only using 1 intake valve allowing the 2 exhaust valve to release the heated exhaust much more effeciently allowing the car to run leaner without the negative side effects of added heat and strain on the valve train

[firehawk618]

Originally Posted by Chrysler kid

You're reading voltage under 1v aat the secondary oxygen sensor to determine lean burn correct?

As far as 3 valve operation on the y5 I have no idea, the upshift light could be saying when the car is out of 3v operation for all I know. Vtec engages when the car is in 4v (16v) mode and opens the valves at a more agressive duration than normal.a

Vtec on the hx is triggered at a higher rpm than the ex model, and I do know the vx would use 3v mode in all gears but honda received complaints about the abrupt change from 3v into 4v into vtec. So I assume 3v mode in the hx is only in lean burn conditions to make the car more friendly to drive in lower gears

I spent a few nights reading up about the man who engineered "lean burn" but I can not recall any spefic functions or features besides creating a swirling effect by only using 1 intake valve allowing the 2 exhaust valve to release the heated exhaust much more effeciently allowing the car to run leaner without the negative side effects of added heat and strain on the valve train

Yes I am watching my rear o2 but I can easily tell without it.

The upshift light definitely has no correlation to 12or 16 valve mode.

I think you are confused about the HX vtec. I can dig up some good info on the cam profiles if you'd like.

It's in 12 valve mode until the Vtec solenoid engages then it's 16 valve mode.

This cross over happens at a MUCH lower RPM than the performance orientated Vtec *EX*.

I can clearly feel mine happen right aroudn 2900 rpm's if i'm heavy on the throttle.

If anyone is interested I will hook a light to it and watch exactly how it behaves.

My hunch is it stays in 12v mode almost all the time and only goes 16v when under acceleration.