streetzlegend

iTrader: (8)

Well after having problems with the car running and leaning out on me, we found out it was a bad o2. Now I have been driving with both bank o2 sensors disconnected. Ofcourse the car runs really rich specially with stock maf and z32 injectors, and the fact that its running of the safe map or w/e. a/f at idle and below 3k (or cloosed loop) is in the 11's.

Now, I have VAFC2. I figured since the o2 sensors are not connected, the ECU is not going to try and fight what ever correction I make in closed loop since it dosnt know where the a/f is at and its running of a predetermined map. So what I did is get into the narrow mapon the vafc2. go to the 1500RPM mark, rev the car in idle to 1500 and remove fuel. When I did this right away I saw the a/f start going up till it passed the 14.7 range, then I made less correction till I got almost near perfect 14.7. Also my throttle %'s are set to 10% and 90%. I started driving observing my a/f. at idle the a/f is now at high 13's(since I didnt have any rpm point below 1500rpm). As soon as you accelerate a/f goes to mid 14's and stays there no matter what throttle position. Basically while driving its at near 14.7 it even fluctuates less than having working o2 and letting ecu make corrections. When RPMs go above 3k ofcourse it goes into the Wide map and thats the normal tuning we always do above 3k. [The correction I made at 1500 rpm is -13.]

The only thing I think might be of some concern is the timing. With o2's disconnected and ECU running of the safe map or w/e it is. Timing gets retarded. Now by making the corrections I did, timing gets advanced back. The thing is, how much does timing get advanced? and is it more advanced than if the ECU was running with o2's?

I think this is a great discovery (i havent read anyone do this before at least) specially for those with large injectors, and SPECIALLY for those with smaller turbos that start to show boost below 3k.

I think depending on the fuel system setup on boosted application, If boost starts coming in at for example 2k or below, that is still in cloosed loop at 14.7 and underboost thats not good at all!!, so now with what i found, i think this can be a great thing that way you can tune for when boost comes in. Thing is, its going to give out o2 codes (Which i dont mind since i permanently have codes, iacv)

Tatanko

iTrader: (34)

An interesting discovery indeed and not a single reply

nismology

iTrader: (8)

Cool beans. Why do you think the timing is getting retarded as a result of the o2's being disconnected though?

Nealoc187

iTrader: (23)

Where'd you get this info. I've never read that anywhere. I had no working O2 sensors on my old 96 maxima and that car did not show any signs of having timing pulled. It went almost 99mph on the stock ECU with only I/Y/MEVI...

streetzlegend

iTrader: (8)

Well I have been asking around because I am not really sure if timing gets retarded when the o2's are bad or unplugged. Perhaps you know?

If timing does not get retarded from disconnecting the plugs, then by me doing the corrections in closed loop I am adding even more timing to the already advanced timing the ECU is doing. I know that at part throttle and below certain RPM maybe 3k (not sure of this) the ECU advances the timing so that there is better response. So maybe its not a good idea that I am advancing it on top of that. I have to get my hands on a logger and check it.

xnyc

iTrader: (9)

since you disconnected the o2 sensors, woudlnt that mean that wat your doing now is adjusting openloop fuel trim?

streetzlegend

iTrader: (8)

isnt open loop above 3K and above 40% throttle? im adjusting the a/f below 3k

nismology

iTrader: (8)

Ahhh...i just thought about it and he's right. When the o2's are disconnected or bad the ECU stays in open loop full-time.


Good catch xnyc.

Tatanko

iTrader: (34)

So if they're in open loop all the time, that does indeed mean tuning below 3000 is possible without interference from the ECU's pre-set tables?

streetzlegend

iTrader: (8)

hmmm thats right. I remembr you telling me that once nismology. and yea. your right Tatanko

xnyc

iTrader: (9)

all your doing basically would be adjusting the ecus preset calculations

Tatanko

iTrader: (34)

I was referring to the fact that in closed loop, the ECU tries to "fight" your adjustments.

nismology

iTrader: (8)

Well, in reference to your original question, there are no "preset tables" in closed loop. It's based solely on o2 sensor feedback.

Tatanko

iTrader: (34)

Really? Hmm...I've read a lot of BS then.

95turbo gxe

iTrader: (25)

Thats great. When I had my 3rd gen I had no o2 sensors. ANd it was no problem with airfuel. Well i can check this out with the eu after I unplug them.

Kevlo911

iTrader: (36)

Why??????? You can tune some in closed loop w/o ecu adjusting back and no cel.

streetzlegend

iTrader: (8)

What are you refering as "no problem with a/f", you mean your a/f did not get rich at idle and cruising from havin o2's unplugged?

Kevlo, well you still will get a CEL since they are unplugged. in mycase I dont care because my CEL is always on for other codes i cant do nothing about, so i dont mind it.

Kevlo911

iTrader: (36)

I gotcha. I tried a lil bit of tuning in closed loop and the ecu did not throw a code or try to go back to 14:7 af.
It would hold steady in the 13's w/o problems. But I have yet to try it long term.

95turbo gxe

iTrader: (25)

No im sorry im saying that when it was unplugged it would not fight the safc. I did not relize my o2 wire got snagged on something and was not connected. When I repaired it and got it plugged back up it would not let me adjusted anymore but i was not aware that was the problem intill now. Good find.

gtr_rider

iTrader: (50)

I told you it was a bad O2 from the beginning, wanna buy mine?

streetzlegend

iTrader: (8)

meh no need, point of the thread is to delete the o2's.

BTW all, i just went on a trip. 4 hour drive to Tampa. while driving i was monitoring a/f. went the whole way in the mid low 14's. so far no problems or anything. So this is a success.

tavarish

iTrader: (27)

Next mod: VAFC, Wideband, and NO O2's.

gtr_rider

iTrader: (50)

interesting

95BLKMAX

iTrader: (10)

just out of curiosity, how many miles did you get on the tanks to and from Tampa? and how do they compare to your previous NA highway tank?

streetzlegend

iTrader: (8)

Well, on the way there I was floored it a few times so that might hurt milage, but when i got there, i had a little bit more than 1/4 tank left, and I had done about 290 miles of travel., the same for when i came back.

95BLKMAX

iTrader: (10)

oh man, thats perfect! If I made that same trip right now I would probably get there puffing on fumes with my bad o2 sensor. Sounds like the WB o2 closed-loop tuning is in deed a success. Congrats Majan! Amberbach for j00 FTW!

streetzlegend

iTrader: (8)

Indeed, you pay.

Chief Brody

iTrader: (2)

You could just pull timing with the emanage right? How's the normal drivability/gas milage while in this forced closed loop?

streetzlegend

iTrader: (8)

Well I dont have emanage hooked up. but yea you can pull timing with it.. i havent filled up tank and driven in the city till it was empty yet. But i did go on a trip and got good gas mileage. as if the o2's were in good shape. ill fill up the tank and daily drive it around city till its low n see wat kind of mileage i get.

dfownz

iTrader: (5)

Can the same be done with a safc, or does only vafc have the capability to do this?

DF

95BLKMAX

iTrader: (10)

Either one. I have an SAFC-1 and it has dual maps (Hi map for the normal tunable open loop, and the Lo map, for closed loop). With what streetz is doing you would tune the Lo map of an SAFC for the same result. But again, you need a wideband o2 to do this yourself and properly monitor it during driving.

jmeister

iTrader: (12)

Well I tried this today since my car's been running rich in closed loop. With the front O2s unplugged I was not able to make any adjustments to AFR via EU either by injector or airflow adjustment. Actually I didn't see any difference in AFRs with the front O2s connected vs. unplugged.
May try to force open loop with the EU eventually but figured I'd try this due to ease and simplicity.

nismology

iTrader: (8)

Try disconnecting the rear o2 as well.

jmeister

iTrader: (12)

well the rear is my wideband

streetzlegend

iTrader: (8)

thats weird man, try adjusting a/f only with maf signal. the ECU shouldnt be fighting it if it dosnt have signal. I dont see how the ECU is going to not adjust if it dosnt even kno what the a/f is in the 1st place.

nismology

iTrader: (8)

Well usually the ECU will try to adjust the a/f back to stoich using the rear o2 if the front o2's aren't sending a proper signal. But he doesn't have the rear o2 connected so it should definitely be in open loop.

And even in closed loop a/f changes are possible at idle with the EU. Hmmm...

jmeister

iTrader: (12)

Yeah, I'll mess with it more tomorrow & see what comes up. I only tried the injector adjustment on AFR self tune.

nismology

iTrader: (8)

Use the regular injector adjustment map. You should be able adjust the a/f to the point of engine stumbling at idle. A put 1 and then 2 in the very first cell and my friend's car damn near shut off.

95turbo gxe

iTrader: (25)

Yeah i did mine through the injector adjustment with the eu