AnotherOldJeepGuy

Originally my ACC position did turn on the radio. Then roughly 10yr back my truck would not start, and the shop replaced the ignition switch. From that point forward and still today, nothing happens when in ACC position. Unfortunately since I don't use ACC that much, it was quite some time from when that shop repair was done and beyond the repair warranty, so attempting a fix on my own is currently on the to-do list, but low priority. I don't remember if it was on during crank, I would assume no, but you know the risk of assumption... Please post your fix, I may copy it!

At the risk of tempting fate , I have ran a few errands and other than the one time just after the first start-up after doing this last work, it is running and idling fine. Also not stalling on foot-off-accelerator decel. So for future reference, it would appear that the solution to stalling on decel in my specific case was either a) the new TPS, or b) cleaning TB / new TB gasket, or both a and b. The other work along the way I am sure was helpful to the overall health of the engine, but the stalling went away with a or b. Thanks again for the assists through the process!

I watched the video of this, and it clearly provides a huge amount of data. My hesitation is I don't know that I would know what to do with all this great data, and I am guessing that the local community college does not offer a course. But I will think on it a bit longer

I definitely would assume the TPS reading was useless and one would think that would make things bad overall in at least some way. But oddly it ran fine and, with the experimental nut in place, came to a calm idle without stalling. Regardless, I did remove the TB and clean it (took about a hour to get it this clean) then reinstalled it with a new gasket, and with the TPS installed so that it was actually sensing the throttle. However the leads on my multi-meter are too fat to probe live as shown in the post from Cruiser, so as a starting point I positioned it roughly in the center of the adjustment. The only way to probe it I can see, with my equipment, is to expose the wires by removing a small amount of the insulation. Not ready to do that on my brand new TPS yet. I guess I could build a small test cable that I could insert at the existing connection with exposed probe points. If I knew the connector part numbers I might be more interested in this approach rather than cutting into my cables. But I don't know the connector part numbers..... Or I might just see if I can find some leads skinny enough to probe the cable as is per the Cruiser instructions. So bottom line, and acknowledging that I have not yet stepped through any calibration, with today's task complete, and, with the test nut removed, the engine is not running as smooth as it was before the effort. It didn't stall yet, but it does idle a bit more rough. I did check that I put everything back in place :) Question is, with the work done today, does this require another ECU relearn cycle?

Great! Good to know I am messing with the right thing, and that just pulling isn't going to do it! If the other end is just flopping around in the column, it would seem I can just pull it on out the bottom, since I can't see it from the top anyway there's not a how lot advantage to leaving it in there.

Well, here is a find that I'll post for the benefit of others with similar experience as I have. What I am calling the TPS Tab needs to be on the other side of what I am calling the Throttle Tab. As I have the new one installed, the TPS is doing nothing. In my pending TB removal and cleaning, most likely tomorrow, I will correct this before attempting the calibration in the Cruiser post referenced. Just another step along the learning curve.

Would you say this is the end/connection at the other end of my broken/cut wire? Does it just pull out or is there a latching of some kind to look for?

Anyone have a vendor and part number? Mine used to look like the one above with the orange triangle. I still have the screw, and the switch is functional, but if I could get the original or a look-alike (3D Printed?) replacement knob it would look much better.

Lots of freedom in the measurement. My first attempt was using a toilet fill valve washer I already had. Size was pretty good actually but the rubber was a bit too squishy. !

NAPA sells a new cap, PN 703-1366, that comes with a new washer, and for some reason I have one I must have purchased at some point, don't really remember when or even why since it is still in the box and not in the Jeep. But I don't think they sell the washer alone. And that washer didn't seal tight when used on the original cap or on the new cap (the original wasn't all that tight either though). So that lead me to making one a little bit thicker that was snug. I got the washer at Elliott's Hardware, but other HW stores should have it. just take the dimensions from @llhat with you and match it up.

After 3 or 4 test drives, my throttle stop experiment sure appears to perfectly solve my issue. Just noting that, not suggesting it is the appropriate (by the book) fix. Since it only has any effect at min throttle, anything above that is working just the same as before, for what it's worth. I do still intend to try the TPS adjustment and additional TB cleaning (a new TB gasket is on order) to see if I can get this working correctly and also per spec without the throttle stop modification. I am making the determination of "perfectly solve" just by listening to my RPM and mentally noting they sound good at idle, as well as I no longer stall when I take my foot off the accelerator. In other words I don't notice that I have induced any higher accelerator-off-pedal idle (other than the idle being higher than when it stalls ). My question is, how would I go about seeing what the idle RPM actually is, given I don't have a Tachometer, adding one is probably overkill, and getting an OBD1 reader is not currently on the to-purchase list.

Yeah I forgot to include that I also cleaned the TB as best I could short of removing it for a more thorough cleaning, but still the next time I'll be taking it off so that I can get to it better. I went ahead and updated that post just for completeness. Good catch.

@pizzaman09 I'll try disconnecting the O2S and see if things work differently after my temporary throttle stop adjustment test runs it's course for a couple days. At the moment that is working perfectly as best I can tell. Which should be a clue rather than a fix, but if all else fails.... So, if disconnecting the O2S happens to makes it run "better", what the heck is the O2S for then!? Seems like disconnecting it would cause trouble if it is there for any useful purpose, so I am confused! I put on a new TPS just because I got one at the Adv Auto liquidation for about $4, but that didn't change anything. Although I suppose that could just mean that the new one is as far out as the original, so I'll take a look at that tip. I have not done anything to check the TPS other than just replace it.

Good Info. I don't know that I have what is needed to move the engine to TDC, but perhaps after I look over the info from Cruiser54's post I'll know that. Once I give my test case a couple days to see what I learn, I'll move on to the next step. The fuel rail does have a release valve although I don't have anything to attach to it. I can see that taping a gauge to the windshield could become problematic

Thanks. I have done all I know how to find and eliminate any vacuum leaks, but my ASTM Degree (Advanced Shade Tree Mechanic) degree is by no means professional. A more thorough cleaning of the IAC / TB is on the to do list since initial cleaning of the IAC did seem to help a little. I don't have any equipment to measure fuel pressure in the failing condition or otherwise, or the expertise to do some of the other things you mentioned, at least not yet. I am planning new plugs, cables, Dist Cap in the near future, although with it running fine other than this one specific issue it makes me feel like these items are not that bad, purely intuition at the moment. I am doing a band-aid experiment right now. I am sure the throttle stop is adjustable although I can't see what is needed (flat-head, Phillips, torx, allen,?), but rather than screw with that adjustment directly (pun intended) I have changed the stop point in a much more reversible way. I don't love this fix, but I am OK with the experiment. This new stop point doesn't really sound like it is idling any faster, and revving in the driveway is not stalling (yet). So I will go with this for a day or two, or until it fails if sooner, to at least get more diagnostic information.

I originally tagged on to this post by BlueDove91, "Intermittent Stalling/Dying While Otherwise Driving Fine...Restarts, Drives, Randomly Dies Again" because of similarity. This was 1/6/25. I had no expectation how long my "tag on" would last! Over time I think my issue has diverged enough that, in hindsight, it should have probably been it's own thread. Too late to start this issue 1/6/25, but I think I should re-title, summarize, and move forward with a more appropriate title. So I will with this post, and with the new title "Stalls At Rapid RPM Decrease, Foot-Off Accelerator, Otherwise Runs Fine". Please follow the saga from that link going forward....

I originally tagged on to this post by @BlueDove91, "Intermittent Stalling/Dying While Otherwise Driving Fine...Restarts, Drives, Randomly Dies Again" because of similarity. This was 1/6/25. I had no expectation how long my "tag on" would last! Over time I think my issue has diverged enough that, in hindsight, it should have probably been it's own thread. Too late to start this issue 1/6/25, but I think I should re-title, summarize, and move forward with a more appropriate title. So I will with this post, and with the new title "Stalls At Rapid RPM Decrease, Foot-Off Accelerator, Otherwise Runs Fine". The problem description may be better stated as "any time I take my foot off the pedal and let the RPMs fall to what should be idle, it instead falls below that RPM and stalls" (which does differ from the OP description). However I can start up any time, and before any acceleration, and it will idle perfectly as long as I let it. So it is only the RPM decrease by taking my foot off the pedal that causes the stall. Whatever is supposed to limit the minimum RPM is not working, or not working fast enough. Over the last two months, these things below have been suggested, and done, and I am sure have been a benefit overall as well as educational, but have not fixed the problem. - Searched for vacuum leaks. Visual inspection was not able to see any cracks or breaks or things no longer connected. Vacuum leaks were found with water spray over just about everything in the engine compartment. Leaks were located at the intake manifold to engine bolt up where several bolt were loose. When sprayed in that area engine RPMs fell immediately. After tightening these loose bolts, the water test was repeated and no longer showed the signs, RPM was unchanged. - O2 Sensor Replaced with new part. - Throttle Position Sensor Replaced with new part. - Passed EGR Test as described by https://comancheclub.com/topic/73480-21-–-renix-egr-valve-test/#comment-769327 - Removed, cleaned and re-installed the Idle Air Control (IAC) which seemed to help at first, but that was a red herring. It helped when I revved the engine in the garage right after doing this, but failure returned very quickly (about 3 starts later). Update: Also cleaned what I could get to in the TB short of removing it for a more thorough cleaning. Pending - Use contact cleaner on electrical connections when I get some DeoxIT or CRC 05103 QD Electronic Cleaner sprays. As @89 MJ said, "I have my doubts it will fix it, but we can hope so!" I will post what happens when I do this, or any other steps taken so that if this ever gets fixed, that will be captured here.

Thanks @75sv1, I'll put that on the watch list.

Success was short lived. While I was able to rev up in the garage and let off and not stall, as soon as I went somewhere, the stall came right back.

I like the insert idea, but didn't read it before I did what I did. I bought a washer, rubber, polyurethane I think, at the hardware store that had the outer diameter just slightly larger than the original (only larger because they didn't have an exact OD match), and a little thicker, then used a hole saw to make the inner diameter match (although lots of other ways to make that cut). Not as cheap as using a spare tire tube insert, if you have or can dig up one. If you need to purchase, the washer is cheaper than buying a tube. No more leaking. Also if your leak is due to the original washer being cracked or dries out, the insert may not be good enough, this will cover that situation also.

I have now messed with the IAC and the verdict is.... I also cleaned what I could without removing the TB. When I do the next tuneup I'll probably remove and clean that too. Thanks to all for the assists over the last couple months or so stepping through this (so far)!

I have not messed with that piece of the puzzle yet. I'll look over the post you provided and see how that goes.

I managed to contort myself enough to get to the last 4 bolts on the underside of my manifold, none were loose. Kinda makes sense since the water test from underneath didn't indicate any gap. So good news bad news. My bolts are tight, my truck still stalls . I am about ready to glue a dime on the throttle at the throttle body stop, so it can't get to the bottom, since that's where it stalls! A bit like how I "fixed" my pass window so that it could not be fully lowered to the point it would not roll back up, with a 2x4 in the door limiting how far down it would go....

Yeah I saw that "recondition" mention and wondered what that was, different from recharging I mean. Can you post the make/model of the one you liked?

Thanks for all the info! I think I'll watch for a good sale on a new die hard for a bit and see if I can get lucky. But if that doesn't come around I will probably give one of the newer cheaper ones a try.