IAC issues

[MancheKid86]

idle air controller bunk (screw was stuck in vaccum line to pretened to be IAC),

replaced it from one at pnp,

that didnt solve the problem,

waaandering idle and lots of smoke,

what could cause this?

something internal??

[skidoo_j]

idle air controller bunk (screw was stuck in vaccum line to pretened to be IAC),

replaced it from one at pnp,

that didnt solve the problem,

waaandering idle and lots of smoke,

what could cause this?

something internal??

 

which motor???

[MancheKid86]

Inline 6

[skidoo_j]

I"ve been fighting odd idle problems with mine for about 6 months, replacing one electrical sensor at a time and changing stuff out. At no point did I have colored smoke. What the IAC if fail would do is the idle would be very high like a vacuum leak if stuck open or sputter out possibly and die if stuck closed. Other then that it's kinda a pot shoot if it hangs inbetween closed open etc.

 

 

I went through 3 iacs from JY and none made a difference. So that's what prompt me down other sensors, but I"ve now replaced everything new but the IAC, needless to say i've bought a new one and it's going in the next time I open the hood.

 

 

The wondering idle could be caused by the IAC but could also be caused by a vacuum line that isn't quite broken and a leak is created during vibrations of the motor. You can use propane or staring fluid to try and chase out a vacuum leak. another thing i did was once the idle is low with motor running disconnect the iac. rev it. if idle drops to same each time and the wondering stops then replace you iac if not keep searching.

 

 

also your map sensor could cause your described problem as it directly affects your fuel ratio so that could explain extra smoke.

[MancheKid86]

replaced all vacuum lines + iac,

when iac plugged in, looooow revs/kills engine,

sounds like its sucks the vacuum from the lines when trying to connect it then poof dead,

disconected,

wanders around 700ish rpm,

driveable

[cruiser54]

Are we sure we're taling about the IAC? IAC has electrical connections, but no vacuum connections.

[skidoo_j]

replaced all vacuum lines + iac,

when iac plugged in, looooow revs/kills engine,

sounds like its sucks the vacuum from the lines when trying to connect it then poof dead,

disconected,

wanders around 700ish rpm,

driveable

 

 

Each time I changed my IAC I found that I needed to drive it a little bit. It's a little motor that pushes a pintle into a seat. So when you first installed it it is in who knows what location, so the computer could be closing it too much. I think someone said 40mph for a few miles usually will exercise the iac to full open. Did you clean the seat in the throttle body prior to installing a new one?

 

As Cruiser said there are no vacuum lines to the iac just an electrical plug with 4 wires and two screws that attach it on to the throttle body. If you've replaced all your vacuum lines on the engine side, did you cap off the vacuum port on the back (cab side) of the intake, it's the vacuum line that goes to the heat control, cruise control, the vacuum bladder, and CAD control if you have it... Maybe there's a leak in that stuff too. I assume you have renix, so are you still using the egr valve? do you maybe have those hoses connected incorrectly that will really screw with the running of the truck or if the egr solenoid is bad and letting partial vacuum through at idle.

 

There are three vacuum lines required to run MAP (on firewall) to throttle body, Intake Manifold to Fuel Pressure regulator, and Valve cover to Intake Manifold. Then there's non vacuum (larger diameter) valve cover to air box, and one airbox to charcoal canister that then goes back to the fuel tank.

Here's a labeled picture of my vacuum with no egr.. This is just how I did it keeping the critical stuff with no emission requirements.