i want to bypass the throttle body on my 85 iroc-z, but i want to make sure i do it right before i just jump in. from my understanding, all you have to do is disconnet the intake manifold water outlet hose and heater control valve/diverter hose, and put those two together with copper or brass coupling. if this is right let me know, if i'm missing any steps please tell me. thanks.

 

Look in the Technical Article and look under Carbs/FI 8th line down labeled Throttle Body Coolant Bypass. http://www.thirdgen.org/newdesign/te...ntbypass.shtml hope this helps. John

 

Exactly!

That's pretty much it though. If I were you though I'd bo a get new hose instead of using the old stuff with a brass fitting.
1- it might not be enough hose.
2- those hoses are over 15 years old.

Have fun.

 

Don't do it, it's there for a reason. It does nothing for performance and it will disrupt proper idle air control especially in colder weather.

 

That's why at the end of the tech article is says:
"NOTE: If you live in an area where extreme cold conditions exist I would not recommend this procedure."

Even though this is the first time I've heard of a problem doing it and I have friends who live in Canada & Alaska and have no problems after doing it. Oh well, I'm just going off of personal experience.

 

Well, as much discussion as it develops, the reason is this. The idle air passage in any vehicle whether carbed or FI is very small. Therein lies the problem. With a large intake and a very small air inlet for the idle circuit there is a tremendous pressure differential. Don't believe me, but check with any licensed pilot and he'll tell you that an idle air passage can ice up at 90 degrees sitting on a hot tarmac. I admit it's the worst case, but the reason they heat the TB is because at idle the mixture is very dependent on the very minute airways, and by applieing some heat the mixture stays fairly constant. At anything other than idle the TB heater is irrevolent. The high flow of air cannot absorb enough heat to really make any difference. Take off the TB heat, and if you use a really accurate tach, or check F/A ratio at idle after the engine reaches closed loop I'll bet you will see a difference. Nobody ever learns that the engineers who develop engine technology know a whole lot more about this stuff than we do. Still not convinced, check with an engineer at any of the big 3, or 4 or whatever. Even my Honda sportbike has idle carb heat-and YES I tried taking it off, the end result was that it flat out would not idle at any set RPM. In fact, it would just stop running. The cause was idle air passage icing. Happened on the hottest days. The best way to go is simply leave it alone.

 

I did it and I'm thrilled with the results!! Of course my car runs pretty hot 240 + , So with this mod I cooled down my feul temp considerably.