Hmmm.... it could be the that you were actually on a slight uphill compared to a slight downhill on your trip. Temperature, drafting, Or maybe you had a big meal before your trip back.....=)

 

I second this. The power limit for lean burn is very low. 70+ can get you near or over the threshold pretty easy. At 80mph, to reliably stay in lean burn, I would expect you are on a slight decline. If you were dealing with a slight incline on your return trip, the extra couple hp needed to sustain those speeds could easily prevent lean burn.

Did you attempt to engage lean burn at much lower speeds, say 55mph?

 

Headwind/tailwind, even a small one you wouldn't notice in a normal car, will make a huge difference. Not just with LB. I noticed some MPG differences in my "new" CVT that the wind explained when I stopped and noticed which way it was blowing.

Sam

 

How do I even know when I'm in lean burn?

 

Without a gauge to tell you, watch the FCD. You'll be cruising along with a very light load on the engine at around 75 MPG. Then you'll see the FCD march up to 125-150. This is USUALLY lean burn. If you even breathe on the accelerator it will drop back down. You want to stay here as much as possible. This is really when you save gas with an Insight.

Sam

 

I would think cold temperature is the culprit, although to concur with some of the above comments, some of my heavy meals may have accounted for barrels of wasted fuel also.

Also, I read a thread recently that convinced me about the CAT temperature playing a bigger role. Is your CAT heat shield in place?

 

No such thing as "same condition" on a return trip a day apart.

 

Instead of releasing the throttle to get into lean burn, once you get the desired speed, barely lift the throttle. That works a lot better.
(My opinion)

HTH
WIllie

 

Yeah I know how to do it... maybe I'm using the wrong words. Point is, it just flat out refused to get into LB, even on a downhill! Why would this happen?

 

Point is, it just flat out refused to get into LB, even on a downhill! Why would this happen?

Off top of my head any one or more of the bellow will prevent getting into LB , even on a down hill :

• In a Purge Cycle
• ICE too cold.
• IMA SoC too Low ... ( SoC under about ~30% )
• ICE Load too High .. ( ICE Load over about ~60% to get in .. once in can go up a bit over ~80% and stay in. )
• ICE Positive load Too Low .. ( ICE Positive Load under about ~30% )
• ICE negative load .. (Air Pump)
• ICE RPM too Low ... (~25MPH @ 3rd gear , ~28@4th , ~32@5th )
• ICE RPM too High .. ( RPM over about ~3,000 )
• Wrong gear... (I don't see LB in 1st , 2nd, Neutral , etc. )
• Throttle (Gas pedal) moving too quickly ... (Slow changes .. ~hysteresis)

 

[*]In a Purge Cycle ??? What's this?

[*]ICE too cold. Nope.

[*]IMA SoC too Low ... Nope

[*]ICE Load too High .. Nope

[*]ICE Positive load Too Low .. Nope

[*]ICE negative load .. Nope

[*]ICE RPM too Low ... Nope

[*]ICE RPM too High .. Nope

[*]Wrong gear... Nope

[*]Throttle (Gas pedal) moving too quickly ... Nope

 

Purge cycle....



The ECM richens the mixture to purge (clean) the second or downstream cat

Likely it would reset at the next operating or heat cycle.... You could try a hill billy reset. ( disconnect 12 volt to reset )

These are touchy little machines..... But fun stuff !

 

Even letting off the throttle will take it out of lean burn. You have to keep the throttle in the sweet spot. Very hard to do for any length of time. With an OBDIIC&C you can really tell more about it. I just built an OBDIIC&C, I was averaging 59 MPG on my 80 mile round trip commute to work. Since I have my gauge my MPG has gone up to 62-65 MPG on the same trip.
Larry

 

My car is now roadable and I'm learning how to drive it. The battery is near 100%. I have no codes. Car has 280k, so broke in well. Per the comments, I see on the FCD it jumping to 75-150 with lightened pedal input after I'm at speed or on a decline. I find the car struggles if I follow the shift light, keeping the rpms below 2k. It doesn't maintain speed well. Even on near flat. Maybe barely. Do you all run at 3k or 2 k when cruising?

Is there a variable on a scanguage to monitor to get a better idea on lean burn?

 

Is there a variable on a scanguage to monitor to get a better idea on lean burn?

I know a Scangauge II has a setting for "hybrid" and you can monitor "Lbn" parameter. IIRC the car is in it when it reads 0.0

 

From many miles of driving, 2500 rpm seems to be the idle cruise speed,..... at least for me.
Both for economy and performance.

HTH
WIllie

 

I've had this issue at least once so far. It works great 99% of the time, but every once in a while I'll notice that even on a nice flat road, or even a slight downhill section, I can't reliably get it to go into lean burn.

 

I'm with Jim on the background charging causing the malfunction.

Willie