Well I got my efi 5.0 all swapped into my 90 Bronco2 and got my harness made just fine but I have one small question reguarding the o2 harness.

I am keeping the single exhaust and the truck has a nice custom y-pipe already with one o2 in it from the 2.9 setup. The 87 Mustang harness Im using has inputs for both left and right HEGO.Do I need to add another bung to my y-pipe to have both sensors or can I just splice both HEGO inputs together and use the single o2 thats already there?

 

Since the o2 sensor will produce as much as one volt, i think you will need to install both of them because under extreme lean, you could be giving two volts back to the PCM on a circuit designed to read 0-1 volt

 

I think you have that backwards....If I only use 1 sensor it cant send 2volts back to ecm. Im just taking the single output from 1 sensor and splitting it into 2 signals back to the ecm. At least thats how I THINK it would work.

 

Oh wow i read that wrong...i pictured two sensors going into one input to the PCM.

As for using one o2 sensor for both banks, i would think that if the o2 sensor is positioned after the y pipe, it would be alright, but you would not be able to richen or lean out the banks individually, they would adjust both banks the same

another thought though, do you think the o2 sensor creates enough current to send up to 1 volt to both inputs at the same time? would you have to worry about one sensor input backfeeding the other one because they would be spliced together? you may have to put a diode in line on both circuits if they could backfeed...ill talk to the gas drive guys at work and see if they have any ideas

 

I welcome any advice they could give. I just dont want to go lay under a car at the junkyard in the mud to pull the o2 harness I need for 2 sensors!

If it cant be done with 1 o2 then I guess I have no other option.

 

You need separate oxygen sensor inputs from each leg of the y-pipe.

 

^^^^^^^^Just the guy I was waiting for! Not the answer I hoping for tho...

Guess its time to weld in some new bungs.