O2 Sensors Acting Weird

[PonyGTrider]

Hi all,
Just appealing to your expertise on this O2 potential issue.
I’ve been having a poor MPG problem for a while less than 9.5 MPG.
A bit of fuel smell out of the pipes (I don’t have the rear cats)
If start the engine from stone cold and take off immediately there is an acceleration hesitation, I pump the throttle and makes popping sound in the mid pipes location then after that it runs normally.
This issue has been going for a while but fat lazy to check my O2 sensors up until now I just monitored both sensors and had a weird reading. It seems like both cut the voltage for a split second. I’ll try to load a couple of short vids (If I can) for you to analize.
When the readings switch to mV it seems to me they miss a reading. Am I right on this assumption? If so could that be part of my ongoing problems?

I will read all of your comments with great interest,
Thank you

.... Well unfortunately I couldn't load the two short videos of the O2 sensors readings but both swith voltage from around 0.1 V to .about 0.7V but there is an intermitent switching to 1.3 - 0.8 Milli Volts. doesn't that mean the sensors lose their voltage intermitently? Is that normal? That happens on both sensors. I measured their voltage back probing the EEC connector pins 29 and 43. The ECM wiring diagram pin 29 supposed to be Dark Green/Pink wire but my harness has Red one...

 

[AeroCoupe]

Did you check for codes? Betting you did but we always ask if it’s not mentioned.

 

[PonyGTrider]

Did you check for codes? Betting you did but we always ask if it’s not mentioned.

No error codes after numerous scans both KOEO and KOER

 

[Mustang5L5]

How old are the sensors, and how are you monitoring voltage?

 

[Noobz347]

I think this ties in with his other thread.

I'm fairly certain that his fuel pump is bad.


About the O2 sensors: They are narrow band sensors. The only thing you really need to concern yourself with is whether or not they "switch" as they are not designed to send a sensor output. On or OFF. If you see that happening then they're working. The readings at the top/bottom of each peak is irrelevant on a narrow band sensor. It just needs to "switch".

 

[PonyGTrider]

How old are the sensors, and how are you monitoring voltage?

The sernsors are maybe 5 - 6 years old. I Back-probed pins 29 and 34 with positive lead and ground using a DMM, and like I said they switch between 0.1 V to 0.7V but it seems like they cut off votage in between those readings and the reading show milliseconds meaning there are some missing contact but the back probing pins were solidly connected.

 

[PonyGTrider]

I think this ties in with his other thread.

I'm fairly certain that his fuel pump is bad.


About the O2 sensors: They are narrow band sensors. The only thing you really need to concern yourself with is whether or not they "switch" as they are not designed to send a sensor output. On or OFF. If you see that happening then they're working. The readings at the top/bottom of each peak is irrelevant on a narrow band sensor. It just needs to "switch".

Oh I get it, It just seems odd that in the middle of the reading both sensors show as if they miss voltage but probably it is irrelevant. Right now I'm running some tetsts troubleshooting the fuel pump failure. Although I didn't see any warnings like Check Engine to show a hard failure with the stop and go issues from the fuel pump, this time I will hold the battery connected to see if the ECM keeps any hard error codes.

Thanks a lot for your suggestions.

 

[AeroCoupe]

I do not believe you will see a CEL with regards to the pump. CEL is only triggered on emissions related codes.

 

[PonyGTrider]

I do not believe you will see a CEL with regards to the pump. CEL is only triggered on emissions related codes.

I’ve red about some codes about the fuel system but I guess not exactly for a failed fuel pump.

Thank you