Trevor

I'm just wondering if anyone has ever put a wideband on a (VE wise) stock car. I'm curious what AFR the engineers tuned the car for at idle & cruise so I can try to reproduce them once I do all the intake & exhaust mods to my car. Well...if nobody has done it I'll probably weld a bung on my stock downpipe and see what the AFR's are.

InsaneGideon

By "stock downpipe" you mean "pre-cat", right?


I thought of getting a wideband as a first-step upgrade. I even bought a ricer O2 gauge in anticipation of it. I just haven't gotten around to getting the wideband, yet...

In any case, let us know what you find out!

maxcooper

Yes, it runs rich as hell (10:1) under boost, and I'm sure it leans out when it goes closed-loop for light cruising. I am not sure what the idle is.

Wade has some info:
http://www.wvinter.net/~flanham/wlan.../3modrule.html

-Max

XSTransAm

i ran mine stock with a wideband. (stock jdm downpipe with no cat), and yes the car ran well into the 10's. It was pretty much always rich.

Trevor

Yeah....I'll put it somewhere after the stock precat. It would be a hair more accurate before the precat but:
- It's still quite accurate...even after the cat(s)
- There's not much room up there for the install
- It's probably a little too hot for the O2 sensor before the precat

I know its some extra work but i think it'll be worth it. Seems like alot pf people tune their modified cars way too rich at idle & cruise. I'd like to make sure what the engineers intended. I think it must be close to 14.7:1 since the service manual shows the "normal" warm O2 output wile idling & cruising as oscillating around 0.5V which means the AFR is probably stoichiometric.

On a side note I have a brand new stock O2 in the car just to make sure it'll be correct. I thought about putting the wideband in the stock location then feeding the stock computer the simulated narrowband O2 output but that introduces some error into the setup since I'm relying on the narrowband simulation circuit.

Thanks for the info Max. I think I stumbled on that page last year before I bought my FD but I forgot about it. I'll be trying for 11.0-11.3:1 at WOT on 91 octane and alcohol injection based on the previous input you guys have given me.

maxcooper

When the car is running closed loop, the mixture will bounce back and fourth between rich and lean. I'm not sure how to read that into a single A/F ratio. Perhaps you can use some kind of averaging function if your wideband unit has one.

-Max