is the iac supposed to pulse when driving durring cold operation or is its job to stay open to allow more air?im haveing hesitation between cold and warm on a crossfire motor. i put 2 iac's from a junk yard chevy 305 motor not fot this car. the hesitation went away. however it idled kind of high at first start at 1500. after driving it went down to normal at 600. these valves worked good but the high idle and a rpm boost after a fast gas pedal press that went above the rpms where i let the gas off at idle.i wonder if the iac's are causing the hesitation, closing when not warm enough and causing a rich condition or opposite causing a lean condition. i'm leaning twords it running too rich being that the gas millage is around 10mpg. also the car does not idle down by itself. i have to put the brakes on and let it idle down in drive. is this normal?

 

The IAC will have no effect on fuel mixture. The IAC is just a computer controled vaccume leak. With a speed density FI sytem it doesn't matter where the air comes from the map sensor will see the change in vaccum in the intake and compensate for it. The only thing a bad IAC will do is either cause a high or low idle.

Your stumble is more likely a fueling issue, start by checking the health of the fuel pump and work from there.

 

fuel pump is solid even under accelleration.unles volume is the issue(pressure is good).not to much more to go to.dist.,cap, wires, plugs, intake seals, heads redone,tbis rebushed,new injectors(which seemed to make it worse
),adjusted pressure reg.,tbis synched,timming at 6 at base. whats wierd is that when i adjusted pressure, hesitaion was at different stages(sometimes after fully warm). only last thing would be esc module,knock sensor(which had the wires almost disconected and wraped with tape). reconected solid. or the ecm or prom. whats wierd is that the timming drops back from 12 to around 8-10 with light throttle and then advances with more throttle. could the wire that was almost diconected have touched the ground and blew the esc module or ecm. should i lean twords that or go with the wierd pressure issue.still stumbles at any range of adjustment, but the least amount with the tab at the bottom(closest to the manifold)?

 

The timing sounds awfully low, it will tend to float all over the place as the stock timing tables are not anything like an old school mechanical advance dissy. Don't worry as the table gets better under load which you weren't gettin in neutral.

I would double check the timing and then get a hold of a datalogging cable to see what's going on. You could have a sensor going flaky, or a number of different problems. A simple log will tell alot.

 

where could i get a cable from? ive heard of win aldl. is this what you are talking about?

 

yep winaldl works great, there are cables on ebay or you can get one from AKM cables.

If you can solder you can throw one together for 5$ with parts from radioshack. The schematics are on the WINALDL site.