Iac Controller?

[over2land]

piece de merde!

What did you do to it since last we heard? Why did it change?

Reason I'm quasi hi jacking, and generally butting in, is cause mine does the exact same thing yours did at the beginning. So, I'm hoping anything that helps either of us, might help the other.

 

[8Mud]

I also believe many things get lost in translation with Renix. It was designed in a foreign country so I don't expect everything in manuals to be correct. I use FSM as a guideline and to help qualify wiring paths. I do wished there was reliable table of operation routines but without that, we are left to figure it out with our best guess and a little experimentation..

I was bidding on the shop equipement, left over, from the closing of the automotive section at a local collage (europe) (in the late 80`s) . And found a box of books. In that box there were a couple of manuals, Design and function of the Bendix engine contoller for the XJ. Pages of bar graphs, bell graphs, tables of sensor inputs and interactions, the whole shooting match, written in engineer speak. At the time, my book shelves were full, thought about snatching all the literature (kicking myself in the rear now). Point is, the study, engineering fact sheets and design literature exists (in English) and was disiminated, shortly before or after the 87 XJ was introduced. It exists somewhere.
I read through some of the literature and the part that stuck, was the inuendo (reading between the lines). That the multi national design team was not a happy group and didn´t interact well. Maybe one of the instructors was part of the design team, the literature contained develpement notes and some stages in the design, along with the finished specs. That´s one box of books, I sure wish I hadn´t let slip through my fingures.

 

[8Mud]

Gently pull IAC pintle

The book says if you pull far enough and pull the piston out and seperate it from the drive, it´s a throw away. I´ve seperted them and reinstalled the piston (drive rod) and had them work just fine, but I never really trusted that IAC anymore. A steady pull works best, feels like there is a little set of drive gears in there (though I´ve never taken one apart to look). I now stop early, before I can see the bottom of the piston.
I´ve also put power to an IAC, while holding it in my hands, the piston ejected about ten feet across the driveway. Being curious can get expensive and embarrassing.

 

[XJXJ]

The book says if you pull far enough and pull the piston out and seperate it from the drive, it´s a throw away. I´ve seperted them and reinstalled the piston (drive rod) and had them work just fine, but I never really trusted that IAC anymore. A steady pull works best, feels like there is a little set of drive gears in there (though I´ve never taken one apart to look). I now stop early, before I can see the bottom of the piston.
I´ve also put power to an IAC, while holding it in my hands, the piston ejected about ten feet across the driveway. Being curious can get expensive and embarrassing.

A little rocking motion while GENTLY pulling the pintle will usually get it moving. Connecting power to a bi-polar stepper motor is not a wise thing to do. It's looking for a "sequence" of pulses to position the motor.

OP - your last description (low idle) sounds like the IAC isn't working at all anymore. TPS topic - Based on the FSM I have, and the input voltage you stated (4.7Vdc) 0.73Vdc at idle stop would be the correct adjustment setting for stick. I'm not saying the other information is wrong but it's different from a FSM that I have found to be very accurate.

 

[over2land]

Well, it's idling right now.

here's what I did. took off the old IAC, which turned out to have a mashed o ring, and swapped it for a cleaned one with good o ring out of the junkyard.

Also swapped throttle bodies, and cleaned the snot outta the one I put on. As a side note, the one on the truck was fairly clean.

Then, reinstalled the new TPS with a good weatherpack connector, and adjusted to .82 or so volts.

After all that it idled at 3K rpms.

So, I found, and turned down the set screw which apparently exists for idle adjustments. I turned it down, when at operating temp, till the idle was just under 750. Ran it for 25 miles on the freeway, and then stopped at a traffic light, and it idled fine.

PBandJ... hope some of this helps you.