I was out datalogging tonight with my cousin, and he had noticed something that i found odd that i had never noticed before. My O2 volts run 700 - 800 then drop to 60 - 10. I tried searching for someone with a similar problem but came up empty handed. I'm running SAUJP3 and the 730 ecm. I had just bought a new Ac Delco oxygen sensor about 2 months ago and it seemed to work fine before. I looked through my old log files to see if it was occuring and maybe i did not notice it (thank *** i saved some of them). I just don't understand what could be causing the sudden drop in volts? Did i maybe overlook something? Any help would be greatly appreciated. Below is the link to my log file.

http://www.angelfire.com/extreme5/branz28/rest.uni

 

Do u have highway mode fuel active?

Will drop that low every time it turns on......

later
JEremy

 

I can't open the log from here (in northern China now), so I hope this doesn't sound stupid, but when closed loop turns on, it changes the fueling to force the O2 to switch low to high and back low and repeat.

Also, any time the engine is leaner than about 14.7, the O2 sensor will switch to below 300 mv if it's working correctly.

Forgive me if this is too elementary for the problem you're seeing. I can't see the log, and can't tell much from what you wrote, just want to cover the most simple answer first.

 

looks "normal" to me........... you do have KR issues........

 

I don't think that i enabled hi way mode, unless it's enabled by default in the S-Aujp3 bin file. I just didn't think the volts were supposed to drop down to 60 and 30... Maybe i'll check my bin file tonight to make sure hi way mode isn't enabled...

 

what's a .uni file?

 

It's a log file created by datamaster, and as far as i know can only be opened by datamaster?

 

Searching for the answer to this problem myself.
Gave up on one car and switched to SD....problem gone.
Still trying to find it on the other car, any input would be helpful.

 

Mine drop's to the 100's then to 800 then to 60, etc. So far i can't find anything to relate it to. I'm already running SD though...I'm wondering if maybe 50lbs of fuel pressure is too much... Maybe that's what is causing my O2 to act funky...or at least contributing.

 

That's somewhat normal unless you're in WOT.
Which is what I was referring to.

 

I haven't checked V3, But I'd swear Hiway mode was enabled in V2. I know the temp quals were low enough to work.
First thing I turned off with my 11-1 CR.