Thanx guys I just didn't realize it was that sensitive to the o2 sensor.

 

Ys o2 sensor are one of the key components of a proper operating efi system ecu read air coming in and exiting and makes corrections and continually alters ..as the engine demands change.. via load fuel altitude heat or cold yada yada you get the point .....also make sure your up to par with regular tune ups

 

Thanx

 

Code 27 is for the sub- (REAR) O2 sensor guys, OP even mentions it. The rear O2 sensor does not affect fuel trims, it is only for catalyst monitoring. and the specific code is for an open/short in the circuit, nothing about functionality.

that isn't to say the main O2 sensor is working perfectly but still. As for the part number of the sensor, read the descriptions. 2wd, 4wd, front, rear, etc.

Does the truck run better on cold start? how about if you unplug the coolant temp sensor for the ECM? could be a bad CTS or extra resistance in the circuit. common in some old chevys for the CTS to fail with a high but not infinite ohms reading...no trouble code but poor performance and lots of fuel since the ECM thinks it's -40f.

 

Is this truck a Cali emissions truck

 

It's got a rear cat o2, I'm sure it's Cali.

 

Guess so I guess I skipped over that part ..Cali got 95 obd2 cars before everybody else did in the states

 

Yup 95 cali, I just order the part. I hope that's my issue cause I sure could of use that money for other stuff. Lol

 

And yes it runs better on cold start.

 

Which one is it?

 

What sensor is this? Thanx.

 

The green one coolant temp sensor
Black cold start injector time switch
Grey one on block looks to be ..oil pressure if that's the passenger side of block
Think the knock sensor is higher up but don't Remember

 

Awesome thanx

 

New o2 sensor is in, check engine still on with same code, after reset with removing negative terminal.

 

OEM manuals are the best to help you in this sort of thing, I scored myself some while I was working at a Toyota dealership. There were these huge cabinet things and there was so many stacked up on there with a layer of dirt. I found my year and "borrowed it". You should definitely try to score some if you can find them. OR... you can be a member of one of my favorite sites where people share so much information. So here is a link to an online copy of my exact book. It should be very much similar to the '95 book.

1993 Toyota Pickup Service Manual

 

Thanx looks good.

 

Didn't realize you we're a Cali obd2 truck I'd figured your were rocking only one 02 sensor
Anyways like kamessama posted its a fault open circuit .check the wiring and conections for burns or rub threw spots or if its oil soaked around the connections .. Try to chase your wiring and inspect it ..

 

I'm not obd2, I double checked all wiring is good.

 

Do you have two o2 sensors ?

 

Yes but no obd2 plug in.