73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => Performance => Topic started by: bootsnixon on May 04, 2008, 12:53:01 am
-
I have an 87 350 TBI. There is no smog check here. If the air pump is recirculating hot exhaust air back into the intake and with an extra belt having to turn the pump, I would think removing it would make a bit better performance and mileage. Perhaps even enough increase in mileage to offset the increase in pollutants ( my eco weak conscience wonders?). Will removing it affect the efi/chip? Thanks for the input.
-
i took mine off. i have had no problems. the exhaust sounds better, ive got true duals, idk about you. the only thing is you have to plug the vaccuum line from the throttle body.
-
The AIR pump doesn't pump hot exhaust back into the intake. It injects upstream at the exhaust manifold and downstream in a dual bed cat. If you take it off you should still be able to pass emissions.
-
The A.I.R. pump doesn't take much power to turn--i believe less than 1hp, so i don't think you'll see any significant performance/mpg gains. But removing it will clean up the underhood clutter.
The efi/computer should not be affected unless possibly, removing the A.I.R. pump causes exhaust temp to change(cooler) AND your truck has one of those exhaust temp sensors AND computer compensates for this by leaning out the mixture?
i don't have my rochester carb book with me; That's where i'm getting my information on this subject--there is a whole chapter devoted to this emmisions control stuff. i need to read up more on this.
-
AIR pump =Legal, but less power just because your engine must turn another pulley. There should be no temp sensor, however it may give bad readings to the O2 sensor, since if you take it off there will be less O2 in the exhaust stream. It may not give you much power to remove it, but may make it run lean all the time if you remove it. Easiest way is to not mess with it unless you know how to modify tbi stuff. (but it's not hard to learn)
-
TAKE IT OFF!!! WILL DEF CLEAN UP INDER THE HOOD AND HAVE MORE ROOM FOR WORKING AND SUCH
-
Now, i recently read that GMC engineers stated that the A.I.R. pump takes up to 15hp to turn at high rpm. They were talking about some of the reasons why a 77 1/2 ton shortbed with the 454 big block could keep up with trans/camaros from 77------the cars had to have emmisions controls whereas the trucks were exempt back then.
This info conflicts with what was stated in the Doug Roe Rochester carb book, chapter 9. D.R. states that the smog pump only takes about 1 hp to turn.
i will try to find the article with the GMC engineers.
At any rate, taking the A.I.R. pump, belt, bracketry, air lines and nozzles will definitely clean things up underhood and regardless of the above conflicting info, it will not harm perfomance. But, i believe that removing the equipment is a violation against federal law, even if your state (like mine) doesn't care if you remove it. So, in other words, you won't get caught and no-one will really care, but technically i think it is illegal.
-
Removing the Pump, will cause your o2 to foul faster, which will also cause your CAT to Fail faster, both of wich will trigger annoying CEL's(Check Engine Light).... If you don't have Emissions in your State, and Won't have it soon, might as well get rid of the other stuff, and have those items flashed out of your Chip/ECM to keep the light off(Or a cheaper way would be to just remove the CEL Bulb, but beware that you can run into other problems that you may need the light to warn against)....