AFR's not consistent

[di_rosa]

hey,

a little history, it's a 2jz with 1j ecu and emu (tuned via injector map), and originally i tuned it and it ran perfect with afr's at cruise and low throttle acceleration were around 14.7. but then the next day, it was like 12.8:1. and then today i had to go on a drive for 30 minutes, and it was 14.7 the entire way, but on the way back, it was damn 12.8.

so i'm figuring the only two things i can think of are the ECU temp sensor or the o2 sensor. but if it was the o2 sensor, why would it work perfectly one time, and not the other? and can i test it by just disconnecting the o2 sensor altogether, or will it mess with timing? i checked the temp sensor against the specs in the TSRM, and they're good.

anyone have any other ideas?

thanks

 

[86_sports_1jz]

check your wideband it could have gone bad, mine went bad and acted all funny similar to that

 

[di_rosa]

so your wideband was reading one thing one day, and a completely different one the next? like mine still switches constantly between 14.3-14.9, and if i use the engine to slow me down it pings 21:1, so i'm pretty sure it's working, but i wouldn't have thought it would give two different readings. i'll steal zazzn's sensor/box then

does anyone know what happens when you unplug the stock o2?

 

[Andre]

I had the same problem and it was my o2 sensor

(setup 1.5JZ stock ecu and greddy emanage 550 Cc injectors etc )

You can also check ereor codes

 

[di_rosa]

yeah, i'm throwing a code 25 which is "lean" code which is associated with a bad o2 sensor

i'm gonna grab another one, and see what happens.

 

[jnianekeo]

What kind of wideband you running? you could run a simulated O2 sensor to your ECU that way you wouldnt need to go buy a new O2. ::shrug::

 

[tsuper92]

my a/f is all over and i have a new o2 sensor.i have no code's and it doesn't smell as rich as the wideband say's.think it's time for a new wideband for me.plx unit must have wet the bed after a couple hundred mile's

 

[Andre]

What kind of wideband you running? you could run a simulated O2 sensor to your ECU that way you wouldnt need to go buy a new O2. ::shrug::

I try that before (AEM ) butt some how the stock ecu do not like that signal

My car was running to rich with simmulating O2 senor signal run like crab

The simulated o2 signal from the AEM does not work with the Stock 1JZ ECU