if you close her more it should idle high. The more you open it the lower its going to idle

 

I haven't had to ever make adjustments to my IAC but here's a procedure for making base adjustment to the IAC.
How to Adjust TPS and I.A.C.

 

i got her runnin again. i now need to figure out why its gettin too much fuel at idle. and how i can cut it back.

 

Well, sweezo....

That's the million dollar question. If the computer and sensors are running at spec then the fuel ratio is set to 14.7 to 1. That's spose to be the sweet spot for complete combustion and power. There are other conditions that might not use this ratio but under normal driving conditions the whole systems will always try to center the fuel ratio to 14.7 to 1. Now for your question, there are a number of things that could be causing a rich condition. There are a couple of primary sensors that responsible for fuel ratio, one and most important is the O2 sensor. The O2 sensor will report to the computer the condition of the unburnt fuel, in a round about way. The computer will adjust the fuel injector to compensate for any condition that is either rich or lean. The cost to replace the O2 sensor yourself is about 50 bucks, so I would make sure that is the cause before you start to swap out parts.

The engine temp sensor, not the dash gauge sensor but the computer sensor, and MAP sensor also have a part in fuel ratios. This is the basic formula for how long the injector sprays fuel.


BPW = BPC * MAP * T * A/F * VE * BVC * BLM * DFCO * DE * CLT * TBM


Where


BPW - Base Pulse Width
BPC - Base Pulse Constant
MAP - Manifold Absolute Pressure
T - Temperature
A/F - Air Fuel Ratio
VE - Volumetric Efficiency
BVC - Battery Voltage Correction
BLM - Block Learn
DFCO - Decel Fuel Cutoff
DE - Decel Enleanment
CLT - Closed Loop
TBM - Turbo Boost Multiplier


you can read the full page here:
How GM Electronic Fuel Injection Works


The catalytic converter, if working properly can offset some unburnt fuel - that's its job. Having the converter working properly is also a good idea for passing emissions.

So, the computer is in control of the fuel ratio through the external sensors. The only way I know of to adjust the fuel mixture is either add resistors to some sensors to change how they report to the computer or re-burn your computer to contain leaner values. But if the computer - sensors - engine are working within spec you shouldn't have any issues passing emissions. My suggestion right now is, if you don't know when the last tuneup was done then it's time to give the truck a complete tuneup.

 

well i had a new catalytic converter, muffler, and tail pipe put on it last week. i changed the oil and i put a new air filter in it. the IAC valve is new. the only thing i aint done is plugs, wires, and the O2 sensor. that will be the next step if she still dont pass after that i will be stumped. i appreciate all the tips and advice. thanks yall.

 

Running my gastank down to under 1/8 and then dumping 2 gallon bottles of METHYLHYDRATE into the tank did wonders on my emission test in BC... Someting about alcohol not being a hydrocarbon... And the engine was much more powerful as well when it was burning mostly clcohol. Afrer I aced the test I just went and filled up the tank with gas to dilute it.

 

hey sweeo , when you put the iacv back in then hook the battery up turn the key on (dont start it) for 5 seconds then off for 10 secounds then start the truck. that should reset the iacv if it dont im not sure how long it should be on my 86 it was 1 1/8 on yours should be the same valve acording to the book i have found it easier to buy a new one then try to adjust them they adjust by pushing down on the pintle and rock them back and fourth also check your oxgen sensor may make it run rich

 

i finished the tune up, new plugs and wires, o2 sensor, air filter, and adjusting the iac. she passed. thx yall for the help. next is new brake pads this weekend.

 

great sorry i didnt relise there were two pages till i replied but i hope it help im going through alot of the same stuff right now

 

Should also take off the egr and clean out the passage with pipe cleaners and some throttle body cleaner. Be careful not to get it on the diaphragm, but clean the plunger passage out especially well with small pipe cleaners. These stupid things gunk up pretty fast, after I cleaned mine it was like a having a whole new truck. Make sure to use a new gasket, $2 at the store.