O2 Sensor Questions
 

I have a 1995 Toyota pickup throwing code 27, for one of the two O2's Truck only has one because it is non california emissions, first question, would it make my truck skip and occasionally backfire? and is it the downstream or upstream O2 if its non cali?

found out it is the upstream, but what would be making a 22re skip besides fuel components?

By "skip", do you mean miss? Backfiring sounds like timing or valve adjustment.

it levels to speed and misfires to the point I have to shift down and let off and try to shift up again. I'm thinking injectors.

Start with the easy stuff: check your ignition timing. Then plug gap.

And pull the EFI fuse (to reset the codes), and then when the CEL comes on re-read the codes. As you point out, if you don't have a Calif. ECU you shouldn't be able to get a 27.

Thanks I will pull the fuse tomorrow, I ordered a new O2 and am going to change it tomorrow also and I will see if anything changes. This truck was just rebuilt has 1,000 miles. timing went and destroyed the case and was rebuilt from bottom up.

If the engine was just rebuilt I can only hope all the tune up parts are brand new.

Did a spark plug wire that was not seated correct come off or burn off??

Burn off against the manifold.:wrench:

Maybe rings not seating has caused a plug to foul out??

all new plugs and rewired, The motor is practically brand new besides the block. I think it has to do with fuel either a clog or problem with flow or something to do with vacuum system. It seems to be a bunch of little things making a big problem

did you ever figure out the o2 sensor issue? I'm currently having the same problem and have a non california model. i am getting codes 21 and 27, i changed the o2 sensor and the code is still on.