02 sensor question

[Birdoprey]

Can the stk 02 sensor be unplugged and the car still run decently? I know the 02 makes small changes to the a/f but is ignored under WOT. I have a LM-1 wideband and was thinking of removing the stk 02 sensor and putting in the WB so i can check my a/f under WOT in one gear. Mainly to make sure there is no problems. My concern is if the factory comp does something with the timming or somesuch if the 02 is unplugged. I just wanna do this to check my A/F. My car blows black smoke when under boost. If its running waaaaay rich i figured i'd lower the fp or up the boost a little.
I'm running 14psi right now. I did up it to 16psi(trying to get the MBC adjusted to 14) and i noticed a slight surge or hesitation. Nothing bad just kindof a loss of power for a second or so during a 3rd gear pull while at or around 5-5500. Kinda thought it may be rich. My turbo Hayabusa did that when it was richer than 10:1.

 

[andymoraitis]

If your wideband O2 sensor is capable of supplying both a narrowband signal to the ECU and a wideband signal for your LM-1 then it would be OK. However, if the O2 only supplies a wideband signal, then you'll throw the car into limp mode by swapping out the O2 and it'll run like garbage. I know the PLX widebands can read both signals, but let me check on the Innovative and get back to you.

Andy

 

[KJS1820]

You are better off having the bung welded in further downstream than the o2 housing anyway! Keep the front o2 in

 

[Birdoprey]

I was just gonna remove the stker and use the LM-1 stand alone for testing. I'll ###### just get a bung welded on in the morning and be done with it. Thanks!

 

[andymoraitis]

That's likely your best option. Let us know what it reads when you run a full pull.

Andy

 

[Birdoprey]

Will do Andy. I'm curious to see it myself. I'm running a small 16G set at 14psi. Got stk 450cc inj, walbro 255 intake(rewired), afpr, ported 2G ehaust manifold, stk 02 housing and down pipe, and 3" from there.

 

[andymoraitis]

My guess is that you're going to see about 9.5:1 or so on your current boost level and I'm sure some of the bucking you're experiencing is from the car choking on fuel. Mine improved when I changed the air/fuel ratio, but the best gains were seen from adding timing in conjunction with the leaner A/F. When you go with larger injectors, you'll have the opportunity to get away from the stock 16 degree map with either an AFC or an EPROM ECU with custom maps (what I recommend). I thnk you should shoot for about 11.5:1, but I'd like for you to have some way to monitor knock since you'll be reducing fuel volume when you take the pressure down.

Good luck tomorrow and I'll check back on the thread to see how things work for you.

Andy

 

[Birdoprey]

Thanks alot Andy. I just hate being broke! RIght at the moment i have on the fuel pressure that is adjustable and the boost. No other way of tuning or even logging. My setup is bit and pieced due to paying for parts that never showed up. Then i just had to work with what i had to get it drivable. I still have the FMIC to install(when i can afford the piping). I hope to have a tubular 02 housing put on and a 2 1/2 down pipe added very soon. Maybe i'll see if the muffler shop can do the down pipe tomorrow. That will complete the exhaust.

I took the car for a spin and watched the boost guage when i felt the surge. The boost is dropping by 2psi and then kinda wavering a little between 12 and 14. I'm running the stk flapper and i ported the flapper inlet but did'nt go crazy. Definately blows a very obvious amount of black smoke when i feel the surge.
The car pulls very good up to 14psi then it seems to tapper off from there all the way to redline. Does'nt fall on its face just does'nt keep pulling like it does on its way to 14psi.
Will most available loggers work ok for monitering knock? I would think that with a logger to moniter knock and my LM-1 that i would have what i need to maximize performance. Of course i will still need a way to adjust fuel. Will probably be a MAFT pro

 

[andymoraitis]

I think if you're feeling a bit of surge and really blowing smoke when that happens, you need to run a proper boost leak test to make sure that you're not aggravating an already rich condition by leaking metered air.

Depending on what size of injectors you want to run, the MAFT will be fine along with the AFPR and wideband for tuning. It's not my preferred method, but with the wideband and logger I'm confident that you can dial the motor in well. As far as loggers, you can have a look at http://www.pocketlogger.com or check the classifieds for a used one. Even ebay has them including pocketlogger or mmcd software. Just make sure it's for an OBD-I 1st Gen and you'll be all set.

Stay in touch!

Andy

P.S. Tell me about broke. I've been trying to buy cams for the last two months!

 

[Birdoprey]

Andy,

Well, things did'nt work out too well yesterday. The muffler shop here in town was swamped. Long story short, i waited around all day for him to gimmie a call when he was free. Never called.
It did allow me the time to clean up the tubular 02 housing that i bought awhile back. Alot of slag inside and the wastegate port was smaller than the turbine housing outlet. I did alot of grinding and smoothed it out alot. I don't like the path that the wastegate tube takes(kinda up and over in a high arch) but i'm sure it will flow much better than the stk unported 1G housing that i have on it now. The turbine outlet will flow MUCH better though.
I hope to get it done some time this week. Really looking into a MAFT PRO and running it in speed density mode.