so i have done everything i could to lower the idle i have got a new tps and i have adjusted everything to the lowest point bac, aic, idle screw, i even tried unplugging a few small vac lines and still nothing i need to get the idle at 750 to pass smog please help. if i take the throttle and force it back the idle will lower but i think that's normal if anyone knows what the issue could be please let me know. thanks

 

welcome

what year?

to me, if it will go lower when you manually manipulate the throttle, then it sounds like the cable and/or linkage is binding.

 

You can get carbon like build up in the throttle that will prevent the Butterflies from closing all the way too.
How are you adjusting Idle,to bring it down.
There is a idle stop screw that will prevent the throttle body from going full closed.
AND LIST YOUR CAR!!!

 

sorry its a 86 fc with a stock 13B in it.
and i am adjusting it with the three different points as stated bac, air idle control, and the idle adjustment screw on the top of the mani

i am going to take it off and clean it for carbon build up next to see if that helps anything.

 

Turbo BAC's are adjustable. NA BAC's are not adjustable.

 

Other things that can raise idle:
Vacuum leak (unplugging vac lines will raise idle, not lower it.)
Throttle cable/cruise control cable too tight
Dashpots on the throttle body are out of adjustment
Thermowax adjustment

 

Check for carbon build up!

 

you don't to pull vacuum hoses, that will raise the idle. I would check for small vacuum leak first then move on to carbon.

 

Thermowax pellet could be bad. Tb needs cleaned. Possible vacuum. Uim amd lim gaskets. Brake booster vacuum line leak or check valve bad. Fuel mix **** may need adjust. Thats just few things off top my head that id check over as they are east to check b4 looking deeper into it

 

i had this issue for a long time on a stock motor as well checked and checked for vaum leaks and nothing. it ended up being that the intake snorkel was jumpered to the steel tube that goes behind the throttle body back into the dynamic chamber. there was no PCV in there... fail.

 

Midnightbluefc-Thanks for sharing. I'm having similar symptoms on my 83 S stock engine. I'll check intake next.

 

What intake are you using?

 

u can use caeb cleaner to check for vacume leaks as weel were ever u spray if there's a vacume leak this will raise the idle aslo checks to c if u need intake gaskets

 

I wouldnt disassemble anything before i`d checked for vacum leaks.
As RRR Motorsports says; Go for the carbcleaner first and spray at everything with vacum

 

If you can get yourself a smoke machine it would be a easy way to find a vacuum leak.

 

another easy way to check for vac leaks is to get a piece of hose (like fuel hose) and put it right up to your ear, then use the other end like a hearing probe.

if you hear a sucking or a wooshing noise, you probably have an air leak at this area. pull one of the vac hoses off and test it out so you can hear what it sounds like first, then hunt around the manifold for a similar sound.

 

let the car warm up, get some brake cleaner and spray it in areas where it may have a vac leak. If the engines stall, you found your problem.