bigbl

hi there,i recently fitted an afr gauge and i get irregular readings, i done a few forum searches and just put it down to them being crap,however i am reading more and more posts on people saying they work fine,maybe i have running issues? when i start the car from cold,my gauge reads about the bottom of the lean bracket,then when i drive it goes up to the top of the lean,if i give it a slight throttle,it reads optimal,bang in the middle, if i floor it,it goes lean and goes off the scale(not even 1 lean bar light up) then once the car is warm,it doesn't read anything at all? if this shows its running lean, what would cause this,a faulty maf or lambda? a bit of a story here but hopefully someone can shed some light. thanks bryan

bigbl

checked it with a volt meter and i get 0.15v from lambda wire on tick over this would indicate very lean? new lambda time?

SW Jay

Is this a narrow or wide band gauge?

bigbl

just taking readings direct from the lambda to get the 0.15v reading(standard narrowband) and the gauge is an auto gauge afr

bigbl

nobody??

c_maguire

Your o2 sensor has to be hot before it will give an accurate indication as regards mixture on full throttle runs (but bear in mind that if the car is run for say a top speed test the sensor can get very hot and may then indicate a lean mixture when infact all is ok). At slower speeds where the ecu is using the sensor readings as a reference for controlling the mixture, then the resultant changes to the fuelling will result in the output of the o2 sensor constantly changing.
My MY00 gives around 0.875 to 0.885v on the OE sensor at full boost and I use a Dawes AFR to check nothing is untoward occasionally.
Kevin


Because the voltages involved are so small, the Earth reference for your gauge or your voltmeter is critical. When I first wired mine in I used the earth at the ecu and took the o2 signal at the ecu also, but the readings were low. The only reliable earth is the -ve terminal at the battery.

bigbl

im going to try driving today with the volt meter attatched and see what readings i get,thanks bryan

bigbl

with the volt meter attatched from cold start i get 0.3 volts on start up, and while driving it goes up to 0.5 volts (still cold) but as soon as it starts to warm up,the voltage drops to 0.02ish, and doest really go up even on slight boost, i am not going to give it a good hammering just now, will this be a faulty lambda giving false readings(and the car could actually be running fine)? or a faulty maf making it run lean? anyone clued up with this?? thanks bryan

Saint AAI

Isn't the standard narrowband sensor only used for closed loop situations when revs and load are low?? A gauge measuring off the standard sensor is pretty useless IMO.

bigbl

the gauge should still tell you to a certan degree if its running rich or lean, my mate that i bought it off had an engine failure before i bought it (straight after the stainless steel headers were fitted if that makes any difference?) and i have fitted second hand engine with all the same sensors ect so dont want to experience another engine meltdown if i can get to the bottom of it now.

Glowplug

iTrader: (8)

I run a narrowbnand AFR and the only time it has given me problems is when the lambda/O2 sensor was fudged, and by the looks of the readings you get on your volt meter i would say your lambda is fudged.

On warm tick over the voltage should flick from 0.1 to 0.9 nearly continually, and on any boost should show on the rich side 0.7 upward

bigbl

thanks b13bat thats exactly what i wanted to know