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Discussion Starter #61
LB is not the holy grail. My Ultragauge tells me when my car does LB, and ist does it quite often although it's not perfect (missing belly panel, steel rims, all season tyres).

So what I have learned: even without LB is is a fuel saving car. It can drive below 4 l/100 km without doing LB. But I know, that's only my driving profile.
What speed and gear do you get under 4 w/o LB and w/o slowing down so much that you have to start applying more throttle?
 

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Usually I drive at about 92-95 km/h in 5th gear on the highway, fuel consumption is 3.7 l/100 km. That one day without IMA and without LB, it did not change. That surprised me a lot.

Perhaps it was a good day with tail winds so that I could have achieved an even better FE with LB, who knows?
 

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What variable is the OBDIIC&C Gauge monitoring when the light goes green? What's the light looking at?

I've got a scangauage 2 and a Bluetooth enabled OBD2 dongle/Torque app I use. Is there a variable I can look at to tell when it's in LB? 02 voltage? Load? etc?

Love to buy a completed OBDIIC&C Gauge, but price is a little out there.

Again, what are the parameters for LB to happen? (Load, coolant temp, speed, RPM, etc)
 

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It's monitoring the air fuel ratio called for by the ECM.
 

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I am talking more about the driveability changes - the sudden drop in power on the transition into lean burn, the abrupt increase in power as you go out of lean burn (eg with throttle movement), and the lack of throttle response in lean burn. It doesn't have to be like this!
Likewise, I find the sudden stop in re-charge braking a bit too abrupt. It should decrease slower.
 

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I've got a scangauage 2 and a Bluetooth enabled OBD2 dongle/Torque app I use. Is there a variable I can look at to tell when it's in LB? 02 voltage? Load? etc?
On my Ultragauge, it is the 2nd O2 sensor. Quite simple. If its voltage is at 0 V, the car is in full LB.

By the way, nice observation: there is no such thing like LB on/off. O2 sensor voltage varies a lot. Normal rich mode: 0.78-0.8 V. But it could be also a "little lean burn" voltage at about 0.2-0.3 V. Or "full" at 0 V.

Olaf
 

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....there is no such thing like LB on/off. O2 sensor voltage varies a lot. Normal rich mode: 0.78-0.8 V. But it could be also a "little lean burn" voltage at about 0.2-0.3 V. Or "full" at 0 V.
Are you sure voltage variation, though, corresponds to degrees of lean burn, 1-to-1? The voltage may vary, but lean burn (i.e. how it's programmed) might not respond in lock-step; there might be cutoffs, groupings, a given voltage range corresponds to X air/fuel, a different range or value corresponds to a different X air/fuel ratio, etc...

On the OBDIIC&C, I typically see 3 (maybe 4) major settings: rich mix, purge mix, normal mix, and lean mix. Rich mix is less than 14.7 to 1 (down to about 12.1:1), purge is 13.7:1, normal is 14.7:1 (or maybe it's 14.3 to 14.7, not sure); and lean is something like 19:1 up to about 22.3:1. The main scheme seems more or less lean burn ON and lean burn OFF, where lean burn ON=AFRs around 19:1 to 22:1...
 

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Are you sure voltage variation, though, corresponds to degrees of lean burn, 1-to-1? The voltage may vary, but lean burn (i.e. how it's programmed) might not respond in lock-step; there might be cutoffs, groupings, a given voltage range corresponds to X air/fuel, a different range or value corresponds to a different X air/fuel ratio, etc... On the OBDIIC&C, I typically see 3 major settings: rich mix, normal mix, and lean mix. Rich mix is less than 14.7 to 1 (down to about 12.1:1), normal is 14.7:1 (or maybe it's 14.3 to 14.7, not sure); and lean is something like 19:1 up to about 22.3:1.
Yes, measuring actual mixtures with a MoTeC air/fuel ratio, that's my memory of what it looked like - although a bit richer and a bit leaner than the ratios you've mentioned at each end of the spectrum.
 

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^So, the Afr values we see on the OBDIIC&C are perhaps targets while the actual values will vary from those targets? And, furthermore, the voltages do reflect the actual Afr values?
 

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^So, the Afr values we see on the OBDIIC&C are perhaps targets while the actual values will vary from those targets? And, furthermore, the voltages do reflect the actual Afr values?
I am going on memory from lots of years ago, but I remember full throttle being pretty rich - low 12s - and lean cruise being incredibly lean - 24:1. I monitored factory oxy sensor voltage with just 2 LEDs - one for rich, and one for lean cruise, so I don't have voltages versus air/fuel ratios to give you.
 

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And, furthermore, the voltages do reflect the actual Afr values?
My 2 bits.

Yes .. within reasonable limits .. ie +/- whatever it's margin of error is.

For example .. It is not compensated for effects like different temperatures .. different intake Oxygen % of air .. presence or absence of oxygenating compounds in the fuel itself .. etc .. etc ... which can effect the accuracy of the final results .. soo just keeping in mind what is does .. the sensor looks for Oxygenating compounds in the exhaust as an indirect method of inferring what the AFR was in the combustion chamber , if certain reasonable assumptions are true about the intake air and the fuel itself that went into said combustion chamber.
 

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OK, so it sounds like what I wrote is the case: the OBDIIC&C Afr values are "targets," while the actual air/fuel ratio can be something different, is usually something different, maybe can be very different(?)... And the O2 sensor voltage readings correspond to actual air/fuel ratios - within reason...

So... When the OBDIIC&C Afr value jumps from say 14.3:1 to 22.3:1, the actual air/fuel ratio might be somewhere in between - and O2 sensor voltage can capture that in-between-ness?
 

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On my Ultragauge, it is the 2nd O2 sensor. Quite simple. If its voltage is at 0 V, the car is in full LB.

By the way, nice observation: there is no such thing like LB on/off. O2 sensor voltage varies a lot. Normal rich mode: 0.78-0.8 V. But it could be also a "little lean burn" voltage at about 0.2-0.3 V. Or "full" at 0 V.

Olaf
So, I set my phone up to look at 02 sensor 1 and 2 voltage. When 02 #1 voltage goes to .4, O2 sensor #2 goes to 0. I'm still kinda getting the feel for it now that I can "see it", so I can't speak to the LB "lite" areas yet.

Waching the mpg meter, I can see how the meter doesn't always reflect LB.

BTW, here's what I'm using to look at the O2 voltage:
https://www.amazon.com/dp/B00SM8R04Q/ref=twister_B01FCZ7OX8?_encoding=UTF8&psc=1

The phone app I’m using is Torque lite and haven’t upgraded to the Torque Pro version, which I might given it’s only $5. So, the grand total if you buy the full app and the blue tooth adapter is $15.
 

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Are you sure voltage variation, though, corresponds to degrees of lean burn, 1-to-1?
I have no idea, but I can see what the 2nd O2 sensor is telling the ECU.

On the OBDIIC&C, I typically see 3 (maybe 4) major settings: rich mix, purge mix, normal mix, and lean mix. Rich mix is less than 14.7 to 1 (down to about 12.1:1)
0.95 V or so, rich mix does not happen a lot. Or do you mean cold start? 1.x V or so then.

purge is 13.7:1
0.915-0.935 V

normal is 14.7:1 (or maybe it's 14.3 to 14.7, not sure)
0.78-0.8 V

and lean is something like 19:1 up to about 22.3:1
Anything less than 0.5 V or so is LB, I assume.
 

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Here's what typical wide band and narrow band O2 sensors output V vs AFR look like.

 

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....0.95 V or so, rich mix does not happen a lot. Or do you mean cold start? 1.x V or so then....
I see Afr drop to about 12.1 to 12.3 near wide open throttle. I occasionally remember to use that reading as a sign to roll-off the throttle a bit when I'm using assist (I like to max-out assist, but not increase the petrol)...
 

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I do not have much WOT experience. But when I accelerate with WOT, it's more like "c'mon, acceleraaaaaaaate!". No time to look at my Ultragauge. ;)
 

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I admit I've gotten a bit WOT-crazed since I installed a decent pack. I find that it accelerates pretty fast/strong, especially in 2nd gear... Yet I use near-WOT mainly in 4th and 5th - to maximize assist. It's usually a pretty sedate affair, plenty of time to check on the gauge readings...
 

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WOT?.....I NEVER go past 34% TPS.

Willie
 
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