Does any one have an idea on why A/F monitor leans out, espicially on highway driving. I boosted more gas on the V-AFC. But it doesn't do a thing

I got a check engine light for 02 sensor. Also, one of the vacuum line tip broke off the charcoral canister is off..........?

 

Most Honda do get good gas mileage, even with the Prelude, so showing lean on highway is no surprise. Try this, hit VTEC and see if its still lean?

How many percentage did you increase on the V-AFC? Try 5 or 6 % and see. If your problem still remain, you might have installed the A/F meter wrong or its defective.

 

If you're lean under WOT then you either need more fuel, or your o2 sensor is bad... You want to be cruising in the yellow (occasionally you can dip to red when you let off) but even going as far as green under WOT isn't bad... and almost expected.

 

Isn't the o2 only making ecu changes under partial throttle? or does it calibrate the maps at all times? I'm not sure. I thought it fell into closed-loop operation when at WOT, using preset values. What do you guys think?

 

open-loop is using predefined fuel maps.

closed-loop uses the o2 sensor to adjust injector pulsewidth at partial throttle / idle.

the ECU uses the TPS sensor to decide when to switch from closed-loop to open-loop.

hth.

Dustin

 

Thanks Dustin. Do you know which mode the ecu goes into when the TPS reads WOT? Also, you may know from fooling with the pms, is there a specific throttle percentage that registers as WOT? Something like 85-100%throttle=WOT. Know what I mean??

 

I am honestly not sure what the percentage is... I could figure it out with my A/F gauge and my AVC-R throttle % meter though I think it is something like 70-80%.

The ECU goes open loop at WOT. It uses it's own fuel maps and does not use the O2 sensor for feedback at all.

Just think of it like this.... when it is "closed loop" it closes the "wiring loop" from the ecu to the O2 sensor... and when it is "open loop" it disconnects from the O2 sensor and disregards it. That is how i always keep them straight.

Dustin

 

So if the ECU gives up "active" control at WOT, then its based on some presets to give you fuel. In that case, a FPR would help you, correct? If you have insane mods.. (me) then you would want to have the ecu re-programmed to have more fuel on the topend... or just get something like a VAFC... correct?

 

Thanks, I had a feeling I was using the terms backwards. I also thought the o2 was irrelevant when at WOT.

JG: I think they're your only options, although I don't know if increasing FP will help any.

looks like neither of us have our beasts on the road.

 

eh.. I'm waiting on JG to get back in touch w/ me so i can order the rings... getting them put in is actually the easy part.

Sorry to hear you're down too bro!!!

 

I've changed my o2 sensor and my canister problem. But what made the car to lean is the o2 sensor. That sucka is costing me $154.00 my price. List price is 204.00.....I had the fuel all the way up to 50%, but now it's at 5% at narrow throttle. And it's 2 bars after stoich. No hesitation, A/F gauge is reading good and no more codes ( knock on wood ) It's time to get some cam and send out my ECU for some higher REV's........... Now it's time for some tuning.

Thanks crew...........

[Modified by D.specs, 9:50 PM 5/16/2001]


[Modified by D.specs, 9:57 PM 5/16/2001]

 

Another question? Where should I set the throttle percentage?