I have a TPI 1991. I have two nb o2 sensors
one on the right side and one on the left side in
the header pipe and they are in the same place
on both sides.
What would cause the right
side to run alot richer than the left side at idle.
The left side does not register at idle, but
does when I get on it and it reads
the same as the right side.

 

Sounds like an injector or two on that side dumping too much fuel at idle and part throttle.

 

I have a few questions to ask to hepl me understand your question better.

1) What type if EFI are you using?
2) What ECM and prom/mask are you using

3) Are you saying that its not even giving a reading? As in 0.0:1 AFR or 0mv.

 

Speed Density 8d yes it does not register and I
can feel like a lean miss

 

Im trying to rule out some possibiltys and learn a thing or 2 myself.

Im trying to figure out how you tied in 2 O2 sensors to a 730' ecm (im assuming a 730').

Thats probaly your problem giving the rochesters are crap. Giving its a batch fire there isnt really going to be any other logicall explanation. As far as the o2 reading funny, how do you have them hooked up. Are you using a stand alone AFR moniter/meter or are you datalogging it with a scantool or a laptop? If its standalone and you just have a seperate AFR meter for one of the sides (prolly right since the drivers is side is stock) then one of the sensors are prolly bad (the one readin wrong). Ill wait till you respond before i go any further. I might be totally off here but i just want to find out how you have to a/d intputs tied in to one channel on the 730'.

 

Yes they are both separate gauges one for each side.
For the right side I tapped into the o2 that the computer
reads That is the side that reads correctly

 

Just a thought, could something be
going wrong with the valve train on the bad side?

 

Are you sure the ECM is connected to the right (passenger side) of the eng? They normally monitor the O2 sensor on the drivers side.

Kinda sounds like the sensor that reads low (left side?) may have become "lazy". That can happen due to age or possibly it may have been posioned. That would explain why it works when you get on it, but not at idle.

If the sensor that reads low is connected to the ECM, it will think the eng is running too lean and enrichen the mixture, making the sensor on the other side read high.

Something else to consider:
The nb O2 sensors will only tell you if the mixture is below or above 14.7 to 1. They can't tell how lean or rich you are running.
You'll need a wide-band for that.

 

Yes, The o2 sensor that is connected to the
computer is on the right side, this system
is in a 75 vette. When I datalog it's 128 across
the board bl and int also new Ford injectors

 

If your BL and Int is staying at 128 then your just running off the NetRes. "limp home mode" The int should be flucuating constantly. Since you have new injectors, i would swap the O2 sensors, gauges or whatever and see if the left side is still doing the same.

I just think a sensor is lying to you.

 

You maybe right, I will try that tommorow

 

Give us an update when you try that out.

 

Thanks for your help.
The sensor was lying
Thanks again

 

NO prblem man. Thats what we are here for. Some of us to learn and some of us to educate. Ones that have learned are now beginning to educate. "Circle of Life"

Glad you got the problem fixed and i hope you are now a TGO member forever