the pacesetter header didn't have an O2 sensor mounting spot on the exhaust manifold, it was on the extension pipe. so i had to extend the wire. theirs nothing wrong with that is there?

i also noticed when i bolted the sensor into place it wasn't sticking into the pipe. do you get what i'm saying?

i also replaced the sensor last summer

The 02 should be dounted down into the exhaust gas flow. The wire extension is ok. You might check the intake vacuum system, and you may save time and $$ by having it diagnosed by a pro.

could the O2 sensor not actually sitting inside the piping cause it to not function properly?

more than likely the gas mileage prob and the shaking are related. it doesnt make any sense that the exhaust would have done anything to the intake or fuel would it? i mean the motor would still burn the same amount and air and fuel right?

Yes. It needs to be in the stream. It needs to heat up, and it needs to read the 02 content to create the voltage the computer reads, so the computer can adjust the fuel mixture needed for the engine conditions (load, rpm, throttle position, etc).

ok, i'll have to get it up on the lift and fix it this weekend or the next.

is there any other clamps besides the c-clamps that i can use to connect the header to the extension pipe? i dont like the c-clamps and i can't weld it because if i do i wont be able to get the header back into the car because of clearance problems

i dont remember if i said this yet but before the header i was getting 21mpg and almost right after it dropped down to 11mpg(put on the header last summer). just a month ago it dropped down again to 5mpg. My question is will it take this long to bring my gas mileage back up?

Well, it sounds like you may have some other issues. After the 02 is re-installed deeper into the pipe, it should help.

You just would not believe all the times a car can have something repaired, and soon after some other thing goes wrong.

Ignorant people (closed minded ones), (not meaning you) immediately think the repair and the new problem are related. I've heard many times over the years, "it never had this problem till you worked on it".

Like changing the spark plugs is why the muffler fell off, or the transmission won't shift out of reverse.

i'm not trying to be closed minded, it is just a coincidence that it happened right after the header was on. i just ran a diagnostic and it showed me the codes 25 and 26 which deals witht he O2 sensor, intake, etc... i'll just have to start checking each one

thanks for all of your help

does anyone know where i can get an O2 simulator for my 1991 supra? do they even make them for that old of a car? since i put in the test pipe my check engine light has come on and this kid that i was talking to said that i needed to get an O2 simulator.