benzico

iTrader: (3)

hi all, just fitted an apexi tt and the o2 sensor voltage is reading 0.05 ish @ idle and when i go for a drive and put my foot down, not high boost, the voltage goes up to 0.35 ish, i have a multimemter connected to the ecu input as i am driving. i have checked the ecu ground, its good, the o2 voltage on the tt is approx the same as the multimeter. my question is - what should the o2 sensor voltage be and is my motor running super lean at the moment? 95 euro spec wagon same as uk model. thanks all

scoobyboothy

iTrader: (1)

under idle and low speed conditions, it uses the o2 sensor keep the fuel in trim, this is closed loop, with WOT and after a certain rev range it goes in to whats called open loop and uses the maf as arimary source to fueling. the voltage should fluctuate to as little as .0v to around .6v constantly and with WOT and on boost it should stay around .9v if it's a standard narrow band sensor. sounds to me you've got a dodgy sensor or there is something wrong with the car.

when on boost mine goes to .94v

splitpin will add more to what i've explained if i've missed anything out

hope this helps u a little bit

benzico

iTrader: (3)

thanks for your help, i fitted the apexi tt just to use the tt feature if i needed to but thought i would connect the afr aswell. i know that this is narrow band but thought it would be good to see what the o2 voltage was and get an idea of the afr. with my voltage being so low i am worried my engine is running lean. not sure if the sensor is sending out the correct voltage for the mixture it is sensing or if the mixture is good but the output voltage is lower than it should, if that makes sense

benzico

iTrader: (3)

just read that when you first turn the ign on you should get 0.1v from the o2 sensor and then this voltage slowly drops off until you start the engine , can anyone confirm this, i am only getting 0.07. cheers all

benzico

iTrader: (3)

all seems ok now, i took the car out for a bit longer and after about 10 mins the sensor voltages seemed to be doing what they should. guess i didnt have the cat/car warm enough earlier. thanks

Glowplug

iTrader: (8)

If it's any help to you, on tick over and and off boost (closed loop) my AFR/lambda voltage is flicking up and down continually 0.1-0.6ish (knightrider stylee) due to the lambda constantly correcting the fuelling. Once you start to load her up (open loop) it settles down and shows steady optimum to rich 0.6 to0.9.

I did notice when my lambda was shot that my AFR meter (narrowband) acted completly differently, reacting alot slower you could actually see the segments changing.

I don't know how the Apexi connects, but when i was fitting my AFR gauge a was advised to connect the earth directly to the sensor earth to avoid any interferance as a mili-volt or 2 can effect the ARF reading, maybe not applicable to your case but i'll throw it it any hoo

I would be inclined to agree with Scoobyboothby and say your lambda is at fault

benzico

iTrader: (3)

cheers for the reply, i think its working ok apart from the fact that the apexi unit displayed o2 voltage is actually lower than the real voltage that my good quality multimeter is reading. will try to work out how much this difference will affect the displayed afr and then decide if i should stop worrying. at the moment my afr is around 17 @idle 14.4@cruise and drops down to 13 when i accelerate hard. remembering my incorrect low reading on the apexi do these figures sound safe. at the moment i am using the ecu ground maybe will try the sensor ground. thanks again for all your help