code 41 and 91 help please

[Mr. Blues]

searched previous posts for help but so far nothing works for my pony...
1991 LX hatch, 5 speed, basic stocker, replaced both O2 sensors, cleaned MAF, no exhaust leak, idles fine, runs great, acceleration smooth no hesitation, recent fuel install, fuel pressure around 44, cylinder balance = 9. timing = 10, orange ground wire secure to back of motor. any ideas?
thanks for all replies

 

[Black1987Stang]

Reset the fuel trims after you changed the o2 sensors by disconnecting the battery for a little bit?

I don't think it matters except for warming up but you can check for power for the o2 sensor heater, should be 12v with the key on run....that orange wire going to the back of the motor is the ground for it.

If you got access to one I would hook it up to a piggyback w/ datalogging to check the o2 sensors for proper signals (rich lean rich lean)...or you can hook an analog voltmeter I believe to the o2 sensor signal wires (29 and 43) and look for the same thing..just so you know the computer is getting everything it should properly. Besides that im running out of ideas too.

 

[Mr. Blues]

thanks for your reply. Today I cleaned the pcv and screen, IAB and EGR thingy...no results but they needed cleaning anyway. Tuesday I take it to some guy who says he has a computer that will tell him what the voltages (?) are...hmmm... we'll see.

 

[Mr. Blues]

Update
Reinstalled drivers side sensor....code 91 disappeared...
Replaced passenger sensor with old "good" sensor..code 41 disappeared
took " bad sensor bqck to auto zone, they will replace at no charge with new one. Hopefully this will be the last hurrah! Thanks for your reply.