i recently purchased a 1988 firebird formula ,the car originally came with a tbi 5.0 .it was switched to a 5.7 ,retaining the tbi. the car runs well but it sometime knocks under hard throttle setting off the service engine light.i ran the codes and came up with codes 43 and 45 .i have recently replaced the oxygen sensor .now i only get a code 43 .ive tried adjusting the timing but to no avail ......any suggestions?.....also while looking over the engine compartment i came across a round canister mounted under the driver side fender towards the front of the car .it has vacuumm lines coming out of it but not connected to anything.the car to my knowledge has no vacuum leaks.any thoughts as to where this would go connected ?....thank

 

Thats the charcoal can. It takes in vapors from the fuel tank. When the engine is running, it sucks those vapors back through the intake system for combustion. So yes, there is vacuum involved with it, but no, it is not a vacuum reserve canister.

Code 43 is the TPS.

https://www.thirdgen.org/newdesign/tech/tpimod2.shtml

That's the basics. Make sure you pull the voltage first.

 

the charcoal can is hooked up .what im refering to is round and a little bigger than a softball. its mounted under the driver side headlight.
(i saw it there while replacing the headlight motor).......thanks for your input

 

As stated above, the softball looking thing, under drivers side front fender is apart of the charcoal canister setup. I am sure of it because I took all that junk off yesterday and routed the fuel tank vent directly to the TB.

 

OOOOOO....Got it!.......thanks

 

That is the vacuum canister, not charcoal canister. It keeps a supply of vacuum for the heater/AC/defroster vacuum controlled distribution system. I don't think it's connected or tied into the charcoal canister at all.

 

Since mine is gone now, maybe someone can actually look under the car and trace the vacuum lines to see for sure, now that is a thought.

 

That round plastic ball holds vacuum for the cruise control. It has nothing to do with the emissions system, or EVAP.