Impossible o2 singal - With log pictures now!!

[Fos]

Hy,

while accelerating, the o2 singal is doing this wied thing that it starts to fall from +0.94 V and once it fells to 0.00 volts, it starts to show like -0.01, -0.03... volts on tester. How can this be possible??? when under light load, it shows +0.80, +0.30 and so on... fluctuates like it's suposed to. What can cause o2 to show minus voltage?

.using all stock.

 

[steve]

What are you using to measure this?

Steve

 

[Fos]

What are you using to measure this?

Steve

I have a digital tester tapped on the first o2 signal wire near the ecu input becouse my af gauge died on me... datalogger just shows 0v when on heavy load..

 

[steve]

Make sure that the ground your using for the tester is the same as the ground for the ECU.

Steve

 

[Fos]

do you have any idea, why the hell does my car run so lean,even if the minus voltage is becouse of the different ground, I shouldn't get 0V on acceleration...

I dont know how to post a log, because my logger saves a .DAT file thet is encrypted and can be viewd only in OBD2 logger.

but here are the images of the same situation, different parameters....

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PS! pay NO attention to the values displayd digitally in thees 3 slots in upper side of the pictures... they are current values showing the end of the graph, not the middle...
so what the hell is going on?

 

[kurtz7485]

When it switches to openloop, it doesn't use the 02s to tune the a/f ratio.

 

[steve]

Interesting log.
What does it do if you ease into the throttle.
What is your idle speed? I

Why does the RPMa and MAF drop off but you still show 100% throttle?

Steve

 

[92redman]

What is your long term fuel trim at those points?

 

[Fos]

What is your long term fuel trim at those points?

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What does it do if you ease into the throttle.
What is your idle speed? I

Why does the RPMa and MAF drop off but you still show 100% throttle?

Steve

When I ease into throttle, it does the same ting as soon as it starts boostikn...

My Idel speed IS messing around, I figure the engine temp sensor may be messing with me, or it could be the o2? Oh.. the trottle cable... oild it once, sometimes still gets stuck.but idle is messing sometimes even when i force the trottle close by hand...

I guess that the rpm and MAF and throttle fall off like they should, but I was logging so many parameters, there probably was a delay in data drancfere I guess... car allso runs like crap....

ANOTHER SITUATION... different point from previous pictures... only going about 3000 rpm.

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[92redman]

Try again, just a couple of the infamous "red x's"

 

[Fos]

Try again, just a couple of the infamous "red x's"

what are you trying to say?
what is the point of your post?
what are you suggesting that the problem is?
what are you suggesting to do to find out the cause of the problem?

 

[ChicksDigBoost]

I had a O2 sensor on a 1g do this, everyonce and awhile the sensor would read .03v or 0.00v. I replaced the sensor and it fixed the problem. Maybe its just I'm not that familiar with 2g tuning but I don't think your LTFT should be changing that much, that quick.

Is your O2 reading 0v everytime you are giving it heavy throttle? Also are you getting a check engine light?

 

[GVR4592]

what are you trying to say?
what is the point of your post?
what are you suggesting that the problem is?
what are you suggesting to do to find out the cause of the problem?

He's saying your pictures show up as red x's, as in no image. They didn't show up for me either, until I refeshed the page.

 

[92redman]

what are you trying to say?
what is the point of your post?
what are you suggesting that the problem is?
what are you suggesting to do to find out the cause of the problem?

A)The point of my post is to tell you to try and post your images as an attachment rather than a link from some other site so we can see more than "x".

B)I haven't suggested at anything being the problem yet.

C)To find the cause, we need more information(see A)

 

[Fos]

A)The point of my post is to tell you to try and post your images as an attachment rather than a link from some other site so we can see more than "x".

B)I haven't suggested at anything being the problem yet.

C)To find the cause, we need more information(see A)

thats much clearer thank you. The picture files are deffinetly up there and may be that the server was having some problems just when you were viewign this threat. Please try to refresh, any new pictures I will try to add as atachments.

 

[92redman]

Ah, they finally showed up for me. It's hard to tell just by looking at them, at least for me. It looks to me like the timing it starting out low when boost comes on and then steadily climbing until you let off. Also, it doesn't look the ECU has made any adjustment for for a lean condition, could it just be a poor connection?

 

[Fos]

Ah, they finally showed up for me. It's hard to tell just by looking at them, at least for me. It looks to me like the timing it starting out low when boost comes on and then steadily climbing until you let off. Also, it doesn't look the ECU has made any adjustment for for a lean condition, could it just be a poor connection?

It may looke like that from the log, but actually when displaying while driving, it decreases as the boost comes and goes back more advanced as I let off the gas.

poor connection between what? the o2 signal wire and the ecu? In my understandings... everything that the logger displays, the ecu sees. If ecu doesn't see, the logger doesnt show.

I have been thinking about that allso... why in the gods name does'nt my ecu add fuel allthough it sees the lean condition....?

 

[steve]

Once your in open loop the ECU ignores the O2 sensor. It's fuel calcs are going to be strictly based on Airflow and RPM.

Can you confirm that the fuel pressure tracks manifold pressure?

Steve

 

[Fos]

Once your in open loop the ECU ignores the O2 sensor. It's fuel calcs are going to be strictly based on Airflow and RPM.

Can you confirm that the fuel pressure tracks manifold pressure?

Steve

That was the first thing I checked... It's pretty hard to keep track of fuel pressure while boosting because of the gauge being so small and is located outside the car... near the wipers.. , but i'm pretty sure that I saw 60 psi of fuel pressure on the boost. There is one thing though... I have the pressure gauge tappen not in the end of the fuel rail, but in the beginning. Shouldn't make any difference, becouse if the pressure is up in the beginning it must be up in the end allso, becouse the fpr what rises pressure is located in the end of the rail.

I allso tried to connect the fpr vac hose directly to intake manifold without the solenoid, incase the solenoid was messing around, but no... no difference.... I allso made sure that the vac hoses were good and clean and correctly tapped.

I try to get one of my friends to monitor the fuel pressure and the manifold pressure while I accelerate, and see if they are changing simultaniously.

I allso found a boost leak in my throttle body, but it's relatively small. Leaking o-ring.

Can it be my fuel pump although the fuel pressure is normal?

 

[Fos]

Once your in open loop the ECU ignores the O2 sensor. It's fuel calcs are going to be strictly based on Airflow and RPM.

Can you confirm that the fuel pressure tracks manifold pressure?

Steve

Yes I confirm that the fuel pressure tracks manifold pressure.
Its rather high than low for the amount of boost, (if thats even possible). But it does show 60 psi of fuel pressure on boost around 0.8 psi....

what now?

 

[Fos]

ok.. changed my o2 yesterday and woilaa, the af doesn't fall under 0.74V . I know it's lean as hell, but still better than 0.00 volts I used to get. Still getting a lot of spark advance decreasement so still have somekinde of a wierd problem.
Got some questions:

1.How much is my intake suposed to hold steady pressue? 15 psi?
2.Can venting my breather hose cause running lean at wot? (still using the pcv)
3. Can defective pcv cause lean at wot?
4.Is it possible that my ecu will learn in time and increase fuel trims so i get ~0.92v readings soon?
5.My ecu learns that i'm lean only if I'm causing the lean condition and going wot, but that really can mess up my engine... am I wrong? Done a couple of wot runs after o2 replacement and i got max 0.8 V reading.
6. what is the max of fuel trim on stock ecu? +25% ?