Last cry for help

HH-Bham said:

I have three dealerships that are convenient to me. I checked their websites. All have form that must be filled in to order parts and then they will reply. Seems cumbersome and I did not see any mention of 30% off. Do they all offer the 30% discount?

Click to expand...

The Jeep Dealerships I buy from are all out of state, and use TradeMotion or RevolutionParts, some kind of app for car parts websites. The retail price and the discount price are both noted with the part description.

Try >> https://parts.moparonlineparts.com/auto-parts/1999/jeep/cherokee/classic-trim/4-0l-l6-gas-engine

I often order Jeep parts from out of state. I do not agree with the tax rate that my state charges me, nor do I approve of what they spend my tax dollars on. I would rather screw over the State on the sales tax and pay some nice Union delivery driver in a white or brown truck to drop off my parts.

WB9YZU said:

...... an IAC Motor/Slug will cause rich idle, stumbling, flooding at idle, lean idle, misfire codes and a host of other ignition/fuel delivery related codes.

Click to expand...

Every time the IAC has gone bad on me, it has thrown a trouble code. The TPS seldom throws a trouble code, and can/will operate erratically for a long time before it does.





.

Tim, There is no feedback on the IAC.
The darn thing is nothing but a motor with a worm gear and a slug with a nylon center. On the ones I came across the nylon has stripped out and the slug would stop at random places. The PCM has no idea where the slug is, just that the results of it adjusting it were crappy.

I got codes which took me to the O2 Sensors, Plugs, looking for vacuum leaks, just about everywhere except the IAC.

Symptoms are as I described in my previous post; rich idle (eggs), stumble off idle, flooding, lean idle, missing at idle, dying at lights.

Once the engine was above 1500, 1600 RPM the engine ran fine.

Must be a common problem because there isn't an IAC to be found on a '96 and up 4.0L in the junk yard.

Seems to me that about what the OP was leading up to, so I chimed in.

WB9YZU said:

Tim, There is no feedback on the IAC.
The darn thing is nothing but a motor with a worm gear and a slug with a nylon center. On the ones I came across the nylon has stripped out and the slug would stop at random places. The PCM has no idea where the slug is, just that the results of it adjusting it were crappy.

Click to expand...

It's a stepper motor so it know how much it moves. The FSM says the PCM "pre-positions" the pintle at key-on which is basically just running it fully closed and then opening it a specific amount (which it's learned from previous idle adjustments). You can get IAC error codes when the pcm makes a change and doesn't see anything happen to the idle, or you can also get one if the driver circuit in the PCM thinks one of the phases of the stepper motor seems broken.