2nd Exhaust Sensor ..help!

[blackcat]

Celica ST183 conv 1991 (3sGE 2nd gen)

accidentally damaged a sensor in the exhaust system located after the CAT.There are two O2 sensors,one before & one after CAT(center of car).The damaged one has only 2 wires to it,what is the purpose of this 2nd sensor & can it be left out?

Any advice appreciated,thanks in advance

[daktari]

Ooer. I would say that it can be left out. Cos i got a new exhaust (Scorpion) and it has no provision for one. Doesn`t seem to affect anything.

See what everyone else reckons. :)

[PAB]

The O2 sensor after the catalyst is primarily there for On-Board Diagnostic (OBD) emissions regulations. The post catalyst sensor reading is compared with the pre catalyst sensor reading to determine the catalyst's efficiency at converting harmful exhaust gases. Since you have a '91 car the USA market was the only regulation active in '91, TMC built a single global specification?? Does your dash have a "engine check lamp"?

Also, many manufacturers use the post catalyst O2 sensor as a method of adapting the fuelling control within the ECU over a period of time, known as "long term fuel trim",but the amount of "trim" is generally very small <10%

If you haven't got a engine check light on, don't worry.

[blackcat]

Thanks PAB

there is a engine check lamp present but not detecting any faults.So I dont think the 2nd sensor as you say, is essential.However,the engine idles very rough & stumbles on acceleration.Im in process of taking out the injectors & subjecting them to some ultrasonic treatment.Apart from that any advice on what to check?

Ive previously given it some injector cleaner treatment which in effect has made it worse.I understand that it'll get worse before it gets better but Ive treated the injectrs a few times but no improvement. :(

advice from any you chaps solved this problem greatly appreciated

[blackcat]

Ooer. I would say that it can be left out. Cos i  got a new exhaust (Scorpion) and it has no provision for one. Doesn`t seem to affect anything.

See what everyone else reckons.  :)

thanks Daktari ;) Is your exhaust system a full stainless steel & de-cat?

(ps. Daktari are you a doctor?)

[daktari]

(ps. Daktari are you a doctor?)

LOL. Wish i was. I could do with the money. :D

Exhaust is full stainless system but still retains the Cat below the exhaust manifold. That`ll be going when i can find a decent de cat pipe.

[Cubic Incubi]

rip out all the emissions garbage, de cat - etc etc. you may burn a little extra fuel, but so what.