Dark Blue Mark

My car recently just shaved through the MOT, the lambda reading being VERY close to the limit. I have a dawes set to 1 bar and an Autometer AFR which I find quite useful.

Does anyone know how it will respond if its faulty. On closed loop is dances back and forward, and 0.5 bar plus, it goes rich. Would it go safe in closed loop if broken and therefore read rich?

MB

dowser

The lambda is used by the ecu for closed loop to swing fuelling back and forther over stoich. If it's under-reading, your closed loop fuelling will be rich.

Once under load or above certain revs (can't remember 4-5k at a guess) the ecu switches to open loop - the only use your lambda is put to then is to provide (relatively) unreliable data to your lambda gauge

Richard

Dark Blue Mark

I though it was only useful when on boost, as the open loop reading provides useful info. I know you can have det / fuelling issues when not on boost, but the on boost reading is the useful one.

At low rpm / off boost, the gauge jumps back and forth, giving meaningless data. I would find it hard to interpret the bouncing readings...

MB

Dark Blue Mark

Ah ha, I get what your saying now. But I was told that reading where it bounces to on closed loop was meaningless?

MB

tweenierob

On idle the display will jump backwards and forwards, this is the ecu searching for 'Lambda' (stoich area).
Ive got an Autometer AFR as well, top lookin gauge!!
Prefer it much more than my Lambdalink that i had before.
Rob

Dark Blue Mark

Cheers all,

Rob, still not sure how it would behave if the sensor was buggered though!

MB

dowser

MB,

Don't confuse what you're using the lambda sensor for with what the ecu uses it for - the ecu doesn't care what the lambda is doing once you put your foot down on the gas...but you and your gauge do

If the lambda is supplying a low voltage to the ecu during closed loop, the ecu will provide more fuel until it gets the voltage it considers to be stoich. Your Lambda gauge will continue to read normally, because it is also monitoring the same voltage as the ecu. But a hell of a lot more fuel is being used.

Only way to check the lambda operation is to either use delta dash or to use a separate lambda sensor to verify the d/p one is functioning. Failing emissions tests, excessive fuel consumption and a horrible petrol stink at idle are all other clues

Richard

Tone Loc

iTrader: (1)

Mark,

My sensor is basically fecked.... my lambdalink now gets 'stuck' at one voltage or slowly decas. This i am told is quite normal, it could however stop giving readings also (weird thing is now and again it starts doing the correct thing... i.e knightrider effect).

I intially thought i'd wired the lambdalink in wrong but i double checked it and then connected a volt meter to the sensor and sure enough it coincided with what the lambdalink was saying.

Better get the credit card out .

Tony.

ozzy

DBM,

If you look at the O2 sensor with Delta Dash the signal has a nice steady wave pattern. That's the closed loop.

When my O2 sensor was fecked it just flat lined or jumped all over the place. Result was the fuelling ran very rich and would have easily failed emmissions.

My MY99 RB5 flew through the MOT with TSL decat downpipe, std centre and an STI backbox.

Stefan

[Edited by ozzy - 1/8/2003 4:48:23 PM]