Help, o2's falling to 0! w/ ds file

[JaBoT]

My O2's are falling to 0! over 4000 rpm and i can't figure out why.
My fuel pressure and volume are good. I just checked it. I also tryed rasing the pe in the chip and it didn't shange at all.

DS File

Thanks

 

[TurboDave]

My first guess would be a faulty O2 sensor!
BTW, those are some ugly knock retard numbers!!! You still got head gaskets?

 

[soonergn]

That was also my first thought. I was experiencing a silimilar problem awhile back and new O2 sensor cured it.

 

[BM Computer Src]

Bad O2 could be it. I noticed there is a long delay of retard recovery. You must have the retard recovery rate set really slow? (not that it has anything to do with the problem, just an observation)

 

[Eric Stage I]

How much boost are you running?

Eric

 

[Lee Thompson]

o2 s

My son had the very same problem. There is a ground wire in the bunch of grounds on the back of the pass. side head ( I believe ) it is a brown wire, that is the designated ground for the o2 sensor. This wire goes to the ecm. My son left the old wire in place and ran a new wire from the block ground to the ecm and piggy backed it onto the old wire at the ecm. The old wire must have had a break in it.

 

[redhotrod]

Lee,
was that broken ground on a hotair car? I recently have the same problem. Also, my rpms cut out to 0 too for some strange reason.

 

[Lee Thompson]

o2

No, this is an intercooled car.

 

[JaBoT]

Thanks for all the help guys. I will try a new o2 sensor tomorow.
As far as the knock retard, that started when the o2 problem started. So i'm gussing whatever is causing my o2's to drop is causing the knock.

Also i am running 21 lbs of boost with exhaust closed, and it goes to about 24 with the dump open. The ds pass was run with the exhaust closed.

Also i have a nother problem.
The rpm's in ds are about 200 rpm lower than my autometer monster tach. I have the wire for the tach hooked up to the tach wire going into the ecm. BTW i have no idea which one is the right rpm!

Thanks for the help

 

[redhotrod]

Hey JaBoT,
Check for vacuum leaks, I found that on my hotair car, my neck adaptor under the turbo wasn't on right after just reinstalling it and it was sucking some major air. Really couldn't tell by driving, other than my vacuum guage on my boost gauge was 5 hg lower. With the motor getting excess air through a vacuum leak, the fuel mixture will not be right, which causes the o2 sensor to read odd. Mine was darn near 0mv, occasionally getting into 700mv, with the ecm seeing the low 02 reading, it dumps gas in and retards the timing, ALOT when down near 0mv. Mine was actually hitting 60* retard.
I would check all your intercooler hoses
good luck!

 

[GRAYGHOST]

Did you ever find out the problem? Had the same exact thing going on today with a friends car..........

 

[Thumper]

Sent e-mail, let me know the readings.

Thanks
Bill

 

[azgn]

I don't understand why you are worried about the 02 sensor at WOT....it has no input at that point...once you go to PE mode the car is essentially in open loop operating off a programmed table in the ecm

02 sensor will not help you with knock retard

any problems you are experiencing at WOT cannot be 02 related

the 02 is there only for smog and less than WOT applications....

 

[JaBoT]

.

I don't understand why you are worried about the 02 sensor at WOT....it has no input at that point...once you go to PE mode the car is essentially in open loop operating off a programmed table in the ecm

Yes, but the 02 can still show you if your running lean or rich at wot. If your running down the track and your 02 readings start falling, get off the gas cause your going lean and will eventually blow a head gasket.

02 sensor will not help you with knock retard

Yes it will. It can tell you if your knock is being caused by and overly lean or rich condition

As far as the problem i was having. It was a bad 02 sensor. I changed it and the problem went away. The strange thing is that it was working fine (switching back and forth) under normal driving conditions.

 

[Thumper]

azgn your absolutely correct, but lets say the computer sees false info as input, say only 160 grams from maf at wot ( do to a miscalibrated or bad ) then what would happen to the program output fom the computer as far as injectors are concerned, could this cause the 02 readings to fall off, and knock to climb quickly?

Thanks
Bill

 

[azgn]

well, yeah, that is possible, but we are now talking about the MAF, not the 02 sensor.......the ecm will read maf values at wot..it does not read the 02 at wot

the 02 will give you a relative reading that is useful for tuning....but it cannot affect how rich or lean you are running at wot

 

[JaBoT]

the 02 will give you a relative reading that is useful for tuning....but it cannot affect how rich or lean you are running at wot

Well sort of. Unless your chip has BLM cell 15 locked, the computer uses readings from cell 15 to calculate fuel for wot. So yes a bad 02 can effect wot fuel.