Hi might be easy answer but prob not !
I was installing an mtx-l in place of existing o2 sensor and using narrow band output
one strange thing happens thou when car is fully warm and I do a re start the idle fluctuates like mad I need to use throttle until heater element is up to temp then it all settles just fine
same thing happens If i have o2 unplugged at 3pin except it never settles
is that normal for a warm engine with 02 unplugged and input not grounded
mtx was set to 0v during warmup so shouldn’t be oscillating either when I replug it in

I’ll try to see what else I can find

1990 s4 auto

cheers
johnny

 

I havent tried it...but many have reported weird results using a wide band sensor to emulate the stock unit feeding the LH..EZK..


the stock O2 system should be more than adequate. Wide band is good for tuning and monitoring. I have a switch that disables the stock O2 sensor signal to the LH when im tuning with an after market wideband set up (Innovate motorsports)

 

Using a wideband O2 sensor to "simulate" the narrowband signal needed for the LH is problematic and not really worth the headache.

Add a second bung, run both. The stock O2 sensor's are very reliable. Any hiccup with the WB system you have issues like this.

 

Thanks guys
was just curious thou with it disconnected and the engine warm shud it have had the oscillating idle
guess maybe should have tried grounding signal pin in that situation to see if it settled
is there any harm or big disadvantage just running open loop in a non cat car as I’m using the x pipes
thanks

 

Hi found this while searching old posts think it describes my issue exactly

There is another potential problem with the sim-NBO2 output: On a warm restart the LH waits a bit (around 20 seconds I think) before going into closed-loop mode. (On a cold start it waits until the car is warmed up). The WBO2 sensor needs some warmup time, and until warmed up the sim-O2 output sits at zero volts which indicates too-lean. So if the LH goes closed-loop before the WBO2 is warmed up then the engine goes too-rich and stalls as the LH tries to compensate. It's a happenstance thing, I don't know how often it happens in real life.

So perhaps I need to adjust the warm up output voltage on the narrowband it’s current set to 0v ? Seems to work fine from cold start and with mtx this is held at warmup voltage for around 60s every start hot or cold

cheers

 

This exact thing was happening on a 90’ GT I was running with the sharktuner set-up. Wideband sensor to a interface box.

Idle speed was fluctuating when warm.

 

so did you manage to get it resolved ?

Anyone tried a different ‘warmup ‘ voltage ?? Seems a few people have had no issues

cheers

 

I changed it back to stock later. No issues.

 

Perhaps I could try setting warmup voltage to mid scale and see if that resolves will let you know
might also be able to select instant output and avoid warmup fixed setting
cheers