So I took my truck to dodge because I was desperate. My symptoms were a rough idle. I have new everything from sensors to motor. The guy claimed that I needed to raise my idle a bit because my 52 mm tb. So he hooked it up to computer and was also messing witg the throttle plate screw which I thought shouldn't be messed with. He claimed that it was tampered with when my motor was put in. I still have an issue and wanted to set the screw back to or as close to normal as possible. Does anyone know how to do this? i read somewhere about pulling IAC plug and then pulling the brake booster line creating vac leak and setting it somehow like that. Does anyone have some tips? Also, why is the screw even there if its not supposed to be touched? Also my truck has a slight shudder when idling normal. Is this normal? I figured its a big v8 so will move a little. thanks in advance.

 

You want to set base idle without any vacuum leaks. None, zero. IAC should be all the way closed, and then disconnected. Set base idle at around 500 RPM or so. When idling normal, it should be smooth as glass. How old are your tuneup parts?

 

Try resetting the PCM. And what brand IAC is installed?

 

The IAC, crank sensor and maf are bran new and mopar. The plugs, wires, cap, rotor, ignition coil (not the yellow one) were all new in January. And I already unplugged the battery and waited a bit. It was definitely stopping the rough idle when he was feeding it more air with the screw on the throttle plate. He was claiming that it was basically being choked with the fuel and not enough air. So he was giving it more, while saying that the guys who put my motor in set that screw to the factory one not the new one. He claimed it needs more air. It worked then it started doing it again just not as bad. So I, like an idiot, gave it a little nudge one way and then the other tryin to narrow it down. And now I don't know where it should be. The haynes has directions to set up to a '98 or so with the screw. So, why would mine be adjustable or even have one if it should never be touched and factory set? I was told you have to set it with programmer, then I was told you have to set your idle 100 rpm lower than your computer setting so it doesn't get confused and bounce around. Can you guys make some sense out of all of this? Or give me some steps to tryin to set it correctly? Thanks.

 

I can't find anything definitive on setting base idle...... not even in the 01 service manual. (maybe I am just not looking in the right place.....)

In any event, you want to set base idle with the IAC fully closed, and disabled. (unplugged) Engine should be up to full operating temp, throttle closed, (at least, not stepping on the gas.....). Try to set it at 500-550 RPM. That should give the IAC enough wiggle room to idle correctly for ya.

Getting the IAC to close fully is the fun part..... It might do so when you first turn the ignition to the On position....... whether it will stay there at that point or not is open to question. I am pretty sure that if you disconnect the battery for a bit, the PCM should then drive the IAC all the way in, to re-initialize it..... but, again, I am not sure that it won't immediately pull it back out some...... Gonna have to play with it, and see what happens.