Wideband AFR issues?

[gofer]

Sounds to me like the switch point of the gauge itself is off and if thats the case then buying a new sensor won't fix anything. The switch point of a narrowband 1v o2 sensor is 0.5v = 14.7:1 AFR. Since your WB o2 sensor is a 5v sensor the switch point should be 2.5v but it seems like its cycling around a higher voltage. My AEM UEGO gauge cycles around 2.8v, I just went into one of my logs to see what the voltage was when 14.7:1 was being displayed.

Unfortunately, if this is the case then I don't know what to tell you other than you might consider putting a front o2 sensor back in and getting a bung welded in the dp for the WB. If you plan on ever getting DSMLink then nows the time to do it as well since you can control the switch point and simulate the narrowband signal with the software itself.

 

[dsmrollerz90]

Yes I have the honey comb.

 

[JMiller]

dsmrollerz90 i think 17.9 at idle and 14.0 at WOT is too lean. I would like my idle to be between 15.0-16.0 and WOT 12.1 and under and cruising to be 16.3 at the leanest. Have you checked for leaks behind the throttle body?

 

[dsmrollerz90]

Yea I checked everything and it all looks perfect but it has been running like that for about two years now. I have never been able to change it, maybe an o2 sensor is acting up? But it would have gone out by now...

 

[JMiller]

Maybe a pre O2 exhaust leak pulling in air.

 

[dsmrollerz90]

I did have a pretty bad exshaust leak for a long time.. That's actually what I am currently working on fixing.

 

[JMiller]

Update:
For anyone who was helping me with this, I finally just bought another DMM and got the voltage reading from the white wire in mode 4. The range seems to be from .60v to 1.4v. I also checked the other modes and they seem to operate in their correct voltage range. I'm thinking I just got a bad gauge, might call aem and see what they think. Here is a video of whats happening *turn your volume down*.

<iframe title="YouTube video player" width="480" height="390" src="http://www.youtube.com/embed/AhJZoJ_yqcw" frameborder="0" allowfullscreen></iframe>

 

[viprez586]

Maybe a pre O2 exhaust leak pulling in air.

Exactly what I was thinking. Definitely your problem dsmroller, but OP pay attention too.

This will fool the Air/fuel sensor into thinking it's lean, and make the ECU correct things rich until it's satisfied. But it will never be satisfied with what the Air/fuel sensor is telling the ECU because there is a leak.

Got a logger? I bet your Fuel trims are whacked max rich.
If you don't I suppose disconnecting the battery will suffice - thus resetting the fuel trims.


Tip - Seafoam is a great product of discovering exhaust leaks.
Do some research on how to properly use this product as you do not want to hydrolock your motor.



On a side note: I've had problems with my Uego before and a lot of times it was the connection on the back of the gauge. Do your connectors look like they got hot? You need a "perfect" ground.

 

[JMiller]

I don't have an exhaust leak, and the issue is the gauges output is supposed to be between 0 and 1v but its sending out a .5v to 1.3v, the gauge is the issue.

I didn't catch that last part about the "perfect" ground, that was gonna be the next thing I checked, but I don't see how a high resistance in the ground side would cause it to put out to much voltage.

 

[JMiller]

04/04/11 UPDATE:

I checked my ground and it was not "perfect", it was dropping 1v. So i re ran it to a better spot with a new thicker wire and BAM! perfect output from the white wire .18v at 17:1 and 1.01v at 10:1 so i reconnected it to pin 76. But i think i knocked something vital loose in the process, because now even with the gauge disconnected it doesn't run correctly. With the car sitting it boggs and stumbles and is dumping WAY to much fuel. If i had to compare it to something it would be like having an intercooler blown off or disconnected and trying to have the car run. I have the car run better with the MAF disconnected. I like videos so here is another one of the new situation. *TURN VOLUME UP TO HEAR ENGINE*

<iframe title="YouTube video player" width="480" height="390" src="http://www.youtube.com/embed/k0qo5hNdiv8" frameborder="0" allowfullscreen></iframe>

 

[bradselph]

Did you reset your ecu?

Possible it learned some very rich maps from when it wasn't right.

Edit: Viper beat me to it before you even posted.

Got a logger? I bet your Fuel trims are whacked max rich.
If you don't I suppose disconnecting the battery will suffice - thus resetting the fuel trims.

 

[JMiller]

Yeah i reset the ECU. Also since i was so close to having it fixed i grabbed a bar light and went back out to mess with it. I re wired the connection to pin 76 and checked ever other wire and un plugged and re plugged the ecu connections and now it runs perfectly, the narrowband signal is cycling correctly the ECU is keeping the AFRs at 14.7:1 and 10.0:1 in boost the idle is super smooth almost like stock(even with my cams) it drives smoother, sounds better and BOOST better. I will got check the car tomorrow when its cold to see hows it runs(to rule a bad CTS) and if all is well this thread will be resolved. Thanks for all the help everyone, here is a video of the smoothness enjoy.

<iframe title="YouTube video player" width="480" height="390" src="http://www.youtube.com/embed/9xlEUoqLayI" frameborder="0" allowfullscreen></iframe>

 

[bradselph]

great

 

[JMiller]

Checked it today and everything is good to go. Thanks again everyone. *RESOLVED*

 

[viprez586]

Told ya man, that ground needs to be perfect.
Glad you got it figured out. Or as we say at work jokingly - "Finger it out yet?"


For those who might be wondering what a perfect ground is.

• If your ohm testing under .2 ohms, anything over this I'm skeptical.
• Voltage drop test - less then .2 volts (Voltage drop tests are superior in ALL ways)
• The ground location must have all corrosion/paint/grease/buggers/etc removed, you want it "perfect" bare metal.
• After you've made your perfect ground - if you've had to remove paint - go buy some anti-corrosive "paint" in an aersol can at your locale auto parts store to prevent corrosion build up.

Same goes for all grounds - especially the grounds for the ECU/PCM.
Remember to test your battery first too, low voltage will cause all kinds of weird problems.

 

[JMiller]

Yeah, i remember when i installed it, i did kind of a rush job the night before i was to put the car on a dyno so a wiring issue wasn't out of the question, it just took me awhile to get another DMM (my bluepoint was stolen) I was dropping 1v in a VD test and and couldnt get B+ when using the ground from the gauge but when i used the chassis for a gound i got B+ and was like high resistance in ground side circuit, ran a new ground and issue resolved.