Help understanding a wideband gauge...

[Dil-Dog]

Hey guys, 

This is my first turbo car and my first time using a wideband... as you can see from the video attached these are readings i am getting at idle and when lightly applying throttle in neutral.

Can anyone tell me if these numbers are good or bad or if anything is wrong? At one point closer to end it kinda turns off for a second and goes to zero... is that normal?
 

It is a turbo rb25 neo with a Greddy FFP, Gt3071r, stock 370cc injectors, and a walbro 255 fuel pump with a stock fuel pressure regualtor. 
 

thanks,

[joshuaho96]

Your idle is probably ok, just make sure your AFR target is correct. You want to idle at stoichiometric AFR to keep the catalytic converter functional. If the wideband is further back in the exhaust it's likely getting some fresh air on it which causes false lean.

Also revving like that at low load in neutral means you are not building any boost. You should not be dropping down to 11:1 AFR like that. Back up your current map and duplicate it, then zero out your transient fuel tables and see if the same issue occurs. If it goes away then the problem is your transient fuel settings, if it remains it's your main fueling table in near zero load situations. Or take a data log on your current map and see how much transient fueling the ECU is adding/removing.

When you revved up high and then released the throttle at the end the behavior of the wideband was normal. That was the DFCO kicking in for a little bit and fuel injection cutting out briefly. Disable DFCO in the engine map and see if the same behavior occurs again, it probably won't.

Edited October 31, 2019 by joshuaho96

[Dil-Dog]

I have a stock r34 GTT NEO ecu and the senor is installed about 35 inches away from the exhaust turbine. My exhaust is almost straight piped i only have a single resonator... no muffler and no cat. 

[joshuaho96]

2 minutes ago, Dil-Dog said:

I have a stock r34 GTT NEO ecu and the senor is installed about 35 inches away from the exhaust turbine. My exhaust is almost straight piped i only have a single resonator... no muffler and no cat. 

If you have a competent tuner this should be fixed pretty easily.

If you intend to drive this car on the street after you get the tune to a good state where you're pretty confident it won't nuke catalytic converters I would put the catalytic converter back in. Exhaust contains a non-trivial amount of carbon monoxide, if you have any kind of exhaust leak under the car it's going to seep into the cabin whenever you stop at traffic lights.