Idle issues
 

Today I got that weird idle again like she wanted to die on me.It would idle back and forth between 550 rpm and 900rpm than she would idle steady just used to happen ever so often now it is like every other day.I have changed the stepper motor cleaned the throttle body I even cleaned the lucas maf she runs great no engine light she is not throwing any codes just need to solve this problem can anybody give any advice thank you all. 1996 SE 123,000 miles and trying to keep her going strong.

Start searching for any vacuum leaks.

sounds like you need to get your base idle set in the ecu

I have to agreee, you have looked for vacum leaks already, and have done everything that you can, you need to have it re-set.
Let us know how you make out.

Today I will take to rover connection in Houston,Tx to reset base idle I will let you guys what happens.

also let us know how much it costs

maybe try this first?:


First remove and clean the idle motor and the port it screws into. Clean the throttle body as well.

On the top of the throttle body you will see a hole (possibly covered by an anti tamper plug) for the base idle adjuster.

Remove the air bypass hose from the throttle body, which will cause the engine to speed up to 2500rpm or so. Unplug the connector to the idle motor after 5 seconds then reconnect the hose.

Squeeze the hose shut with needle nose vise grips and adjust the base idle using an allen wrench to give an idle speed of 6-700rpm. Get the lowest speed you can that gives smooth running and does not stall when blipping the throttle. Screw in for slower idle, out for faster idle.

Reconnect the idle stepper and remove the vise grip and you should be done.

I set my base idle to 1100 to keep it from stalling out when stopped at red lights, but it idles smoothly, and will not stall now. I have a 1995, and i'm not sure if this works on 4.0 engines

Different truck, different system.

YOu have a distributor, and in 96, they went with coil packs.

Adjusting the base idle is not a DIY job, set it to high and you will mess up your MPG and it will be hard on your driveline when you put it in gear.
Set it to low and the truck will stall under load.
The tach is not accurate enough to adjust it yourself.

Thought I posted this earlier, but it isn't here...

Check the little vacuum hose on the passenger valve cover. Pull it off to check the oil separator in the hole. It looks like a little plastic crankshaft. If it is dirty, clean it off and re-install. Check the hose for leaks, and also the possibility of collapsing. If this line gets blocked, it will drop your idle.