How to adjust Idle on 2.8 v6?

[Forlorn]

I got an 85 bronco ii that I am fixing up as a project car, got the car running now it's adjusting the high idle, it probably idles around 2k at the moment when it should be 800-900 is what the hood label says.
being new to carbed engines this looks like a lot to me, anyways I was on step num #74 where is the tach test terminal? if I even have one, and not go by ear.

 

[Forlorn]

clicked on 2.9 when I meant .8 still would appreciate any help.

 

[snoranger]

I moved it to the correct forum for you.

 

[AndyB.]

Green and yellow wire on the coil, I use an alligator clip to connect to the terminal, then clip the tach to the alligator clip.

 

[Forlorn]

Green and yellow wire on the coil, I use an alligator clip to connect to the terminal, then clip the tach to the alligator clip.

IS the Dk GRN/YEl the negative wire going to the coil then?

 

[Angie]

One thing to check and be positive about is that you don't have any vacuum leaks, they will send you idle settings out of whack even before you touch the carb.

 

[Forlorn]

One thing to check and be positive about is that you don't have any vacuum leaks, they will send you idle settings out of whack even before you touch the carb.

I may have some, but I've been pretty thorough in making sure they're capped if not connected.
another thing I noticed is it revs at 2.5k and if I rev the engine through the carb, like push the accelerator or whatever it called on it, it goes back down to idle at 900ish, maybe something is stuck from it sitting, probably just really need to clean the carb

 

[AndyB.]

I may have some, but I've been pretty thorough in making sure they're capped if not connected.
another thing I noticed is it revs at 2.5k and if I rev the engine through the carb, like push the accelerator or whatever it called on it, it goes back down to idle at 900ish, maybe something is stuck from it sitting, probably just really need to clean the carb

Probably not.

It sounds like you’re in over your head. There could be a number of causes for the high idle, you’re just going to get a bunch of guesses here. You’ll wind up replacing your coolant temperature sensor, throttle position sensor, idle speed control motor. Then you’ll decide you need a rebuilt carburetor. Someone will tell you to remove the EGR valve and the smog pump for more horsepower. Eventually you’ll give up, install a Chinese carburetor, rig up an ignition system from a GM vehicle, the complain you get 13 miles to the gallon.

Try to find someone capable of working on these that will go through the diagnostic steps to find and repair the root cause rather than guessing.

 

[fastpakr]

Probably not.

It sounds like you’re in over your head. There could be a number of causes for the high idle, you’re just going to get a bunch of guesses here. You’ll wind up replacing your coolant temperature sensor, throttle position sensor, idle speed control motor. Then you’ll decide you need a rebuilt carburetor. Someone will tell you to remove the EGR valve and the smog pump for more horsepower. Eventually you’ll give up, install a Chinese carburetor, rig up an ignition system from a GM vehicle, the complain you get 13 miles to the gallon.

Try to find someone capable of working on these that will go through the diagnostic steps to find and repair the root cause rather than guessing.

That's a remarkably cynical take when no one has suggested shotgunning parts at the problem to date.

 

[Angie]

Ok, I really don't want to get too involved in this thread, however, there are a couple things i would look into. on the couple 2.8's engines i have come into contact with in these trucks, they are at the start of the "electric, and sensor" era ... with all the small hoses and gizmos on the fender skirt. are all these connected properly? and can you take a couple pics of them all. as from what i can gather they are what control the engine, and control the settings. myself I don't have a running truck with these things still attached, but i am thinking we need to know if yours are still there.

Second, can all your troubles be that the high idle screw is not working properly and is just sticking? something sounds like it is a mechanical problem and not a carb problem where you need to tear into "rebuilding" and going into the troubles you are seeming to want to take.

carbs are really not that complicated once you understand the basic functions of them.

give you an example, i recently bought a 84 truck with 2.8 that had a crazy idle problem.... after checking all the vacuum lines and such i was able to decipher that the brake booster was blown. Hence the vacuum leak and off, missing idle.

cheers and post up what it is you are looking at.

post #5 has a picture of what i am talking about. not saying yours is shot, however, this is something that is over looked on older trucks. they do rot and these are close to 40 year old rigs.

1984 ranger roll-along

Starting a new thread here with the newest ranger to enter our fleet of vehicles. From this thread carry forward..... https://www.therangerstation.com/forums/index.php?threads/seriously-thinking-1984-camper.199943/ UPDATING: ...... (Missing key for the tumbler, was going to replace it with a...

www.therangerstation.com

 

[4x4prepper]

How about a picture of the engine from the passenger side and a picture from the front of the carb with the air cleaner removed? No sense in trouble shooting a system step by step if it is not stock going "by the book".

If it was me, I would let it warm up and once I was sure the thermostat was open, I would test it for base timing (no advance), vacuum at idle with base timing, and see where teh RPM range is then.

 

[Angie]

Any follow ups on this problem?