removed air pump= low idle and hesitation
 

today i did a few things to my 85 12a, first i removed the clutch fan and installed my new jegs electric fan w/ adjustable thermostat control...works awesome:) love it.

then i took the air pump off, blocked both intake manifold ports with block off plates, and tested to make sure they dont leak by spraying carb cleaner at them when idling....they dont leak.

but it now idles at about 500 RPM when it used to be at around 800 and there is a heavy hesitation if you romp it from 500(it will kill if u go to the floor rigth away) but if you rev it up to 800 rpm and them romp it to the floor it runs great

any sugestions thoughs or ideas guys?
thanks

Readjust your idle and mix to match the new intake conditions. Sounds like the idle circuit is now starved for airflow.

And realize that without an air pump your cats will slag out pretty soon. You really should only remove the air pump when you switch to headers and a non-cat exhaust.

ya thats why i removed it because soon im getting the rb header/intake system and running with no cats just muffler.

i adjusted the iaa i believe its called and it runs great now

thanks

No prob; congrats on the fix!

hey could you help me identifi screws on the nikki? i found one under the throttle linkage on the drivers side it looks liek a brass screw and its phillips head...i thought it was the IAA but im thinking now that its just the idle speed and i cannot find any other, could you tell me were the idle mixture or IAA screw is? i cannot find it anywhere
thanks

it looks like the MAS is what im lookign for, but it was a metal cap over it...what do i do?

got it, my bad

hey guys still having some problems and ive been playing with the idle mixture screw and idle speed screws and cant seem to fix it....ever since the air pump removal its been starting hard, before it would always start right up on teh first or second crank but now it needs LOTS of gas pumping and wont start with the choke on, the choke has to be pulled on as soon as it starts to keep it running...whats going on?

if i knew it was this much of a PITA i would have just left the air pump on but im getting a header and replacing my cats with mufflers soon. any help would be greatly appreciated thanks all

bump

Check your hoses to make sure they are tight and no vacuum leaks. Had to replace a couple of mine.

Regardless of where it idles, adjust the fuel mixture first. Listen and feel the engine to find the spot where the engine runs the smoothest.

Then readjust your idle speed to @ 800 rpm.

Tweek the mixture again to confirm the "sweet spot."

Let the engine idle, then rev the engine and take your foot of the accelerator while you watch the tackometer. If the fuel mixture is right, the tack should settle smoothly to your idle speed. If it bounces or dips before settling at idle, then adjust the mixture slightly.

When the engine runs smooth and the tack returns directly to idle without bouncing, you should be good to go.