So my friends gsr is smoking at high rpms..can it be possible that its because the car dosent have a o2 sensor and a cat? It's running a stock b18c1 on a stock p72 ecu

 

what color smoke, white, blue, black? why doesn't he have an O2 sensor? Are you talking about the primary or secondary O2?

 

black smoke that smells like gas yes, that would be from the o2 missing, blue smoke or white smoke is a no, that's engine wear and water entry

 

i believe its black smoke and does smell like gas...and didnt know it had 2 o2 sensors...where they located? well he bought the car like that it has a straight pipe and check engine light

 

the important o2 is the front one, or only one in 94-95 obd1 cars. the secondary in 96+ checks catalyst efficiency and has no effect on how the engine runs but will set a CEL. the main o2 would be located at the end of the header or directly in front of where the cat should be

 

yea car is obd1...so im guessing thats why car has a check engine light right? and because of no cat?

 

it's because of no o2, you can run no cat with obd1 and not have a cel. i have no idea what idiot installed a straight pipe and didn't tap it for an o2. you'll pay for the o2 in a few tanks of gas. without one you get about 18mpg, with one it's near 30mpg

 

wow good thing to know that...will be installing one asap then

 

Not to thread jack but to stay on kinda topic: I'm working on my friends car and he has an OBD1 engine in an OBD2 car. There is only ONE O2 sensor thats going in behind where the cat would be because the previous owner installed a test pipe and they removed the main O2 sensor. IDK why you would do that either.. His car blows the black *** smoke and it doesn't smell like anything. It also doesn't sound too great either. If they wired in the cats O2 sensor to the OBD1 engines main O2 sensor hookup that the car would run terrible?

 

he needs a main o2, the secondary one is just a plug in this case. if it's an obd1 ecu get an obd1 o2 and tap the pipe with a threaded bung, screw in, clip it in place and the car will run a lot better

 

his car should still have a bung on the downpipe though. that's where the primary o2 normally sits on obd1/2 dc's, no?