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Discussion Starter #1
Hey,

In trying to track down my problem (See "No Light, No Code, No IMA" thread) I need some information. Any help with those who have OBDII readers would be greatly appreciated.

What is the primary O2 (LAF) sensor voltage during lean burn? It should be a narrow range.

During idle stop?

During regular closed loop driving?

I took my measurements driving at around 40 MPH, with the intake air temp being around 70 degrees F, and the car at normal operating temperature.

Any help would be great. I have an appointment on Wednesday to take a Honda tech for a drive, and these readings would be very beneficial.

Thanks!
 

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This is based on a recent trip.

When I first started the engine it was about 1.08 for a few seconds, then dropped to about 0.5 as I am idling down hill (about 1 mile downhill for me at start of all trips). Then it drops to about 0.2 and stays around there while sometimes, with just a touch of throttle (very very little) it goes to about 0.5 still on the way downhill essentially and hence only tiny tiny throttle increases to get around a curve or over a short flat spot on the way down. Then it's about 0.5 whether there is throttle or not for a bit...

It seems looking at the graph (how I wish I had a PC and not the Palm OS software) that with a throttle of around 10% to 25% reading as 'absolut throttle position' it ranges from about 0.5 to 0.2 often stable at 0.4 but not always clearly dependent upon the throttle position. In other words, you might think that it would be directly proportional to throttle position as that would be determining rich or lean, but I guess it also is depending a lot on loads, and maybe I give it a little gas to speed up on a flat area vs. a little gas to go over a hill and that makes the burn differenent for the same throttle position.

I guess as I am watching the graph flow by, I would say that as a rule it is never much under 0.185 (throttle 9.8% for this lower voltage reading) - idling I guess. Then, as I am driving around with never much throttle at all, it goes up to about 0.5 V but not over for throttle up to mid 20% readings.

I see it jump to 0.5V whether I throttle briefly even up to 35% or to 20%, and it does not always go down to 0.18 range every time throttle drops. Therefore, I think the lowest readings of 0.185 were either fuel-cut or autostop, but I could be wrong.

I have no meaningful data right now for throttle over about 35%, but in all the driving at low throttle of about 22% it stays at around 0.5 V. Steady throttle of 35% maybe makes it go up to about 0.6V at most.

From what I have, I have no way to tell lean burn from normal, but if you were to stick me to give an answer, I would say that lean burn is about 0.4, normal cruising at about 20-22% throttle is 0.5V, auto-stop is about 0.185. Maybe lean-burn is actually the same as cruising (0.5), but that makes no sense to me since it is supposed to be extra lean at lean-burn.

Hope that helps.
 

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Discussion Starter #3
Hmmm...Thanks for the info.

What I'm really curious to find out is the voltage during lean burn and auto stop. They will be the key to solving my problems.

Since you mention that idle stop is about 0.185, then things are starting to make sense. I'm seeing about 0.220-0.250 at idle stop.

Thanks for the help so far...

Does anyone else have some solid measurements during lean burn?
 
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