AnotherOldJeepGuy

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.

My 40 year old Sear Diehard finally did die, so I would like to get a replacement. It looks like most of the chargers similar to what I had, go for $50 and up. In my browsing, I see a lot of "mini chargers" out there that according to the words, work essentially as good as the old personal style, and at half or less the cost. It sounds like these small chargers are actually better (better controlled charging, protection, etc.) than the old style with the exception that they don't include the full current needed to start the vehicle with the charger. Any experience with these $20 chargers you would like to share? If providing start current is not a feature needed, what else might be a reason to spend 2x-3x to charge a battery? Example of what I call old style: Example of mini-charger from Walmart:

Those are all well and good, but clearly the WV Mountaineers cover is the way to go.. .

A1: That sound logical A2: The "x" I see downloads the file rather than deleting it....

A couple questions actually. Q1: If a file is deleted from My Attachments, does it remain in posts it was originally put in? Q2: How do I delete a file from My Attachments? I can only appear to view or download, I don't see how to delete. Thanks

DeoxIT seems to have lots of good reviews. Also ran across CRC 05103 QD Electronic Cleaner that also has good reviews. Both claim to dry quickly without leaving residue and will not harm plastics. So will probably get one or the other and give it a try.

Will do. I did stop at ACE HW today and they said they do normally carry something with the name contact cleaner, but were out of stock. We are in for a deep freeze here in North Texas for the next few days, so the search will resume after it warms up a bit.

I was able to visually verify they exist and don't look loose. Trying to get to them is still on the list but so far I have not been able to get to them with a wrench.. can't see them from the top to aim the wrench, and so far I can't reach them from underneath! So since for the other areas the water test was very effective in locating leaks on that end, and also in showing afterwards that tightening closed the leaks at those points, I am for the moment assuming that since the water test from below doesn't show any leaks (ie rpm does not change when sprayed), they are no leaks there. I know that is not the same as being 100% sure with a wrench, but it seems to be good evidence that they are not leaking based on how well it worked in other locations. Does that seem logical?

They all look connected and I don't see any that look damaged. But maybe I'll disconnect and reconnect them just to see if anything changes. Back when Radio Shack existed they sold a contact cleaner spray that worked wonders on TV and CB tuners, wish I had a can of that stuff to clean the connections as well.

I decided to assume that moving the plunger/shaft piece in the blue square in the pic I posted last time, since I can't see anything that looks like what I would call a "diaphragm", would be how to perform the Valve Closing Test. As soon as I was able to move that piece to the right (away from the intake) the RPM dropped immediately. Since this is the pass criteria for the Valve Closing Test, it would appear that it passes. So, given both the Valve Closing and Valve Opening tests passed, it would appear my EGR valve should not be the issue, at least not according to the link 1 test. Without something to measure vacuum, I have to stop at this point on that part and not do the link 2 test. It's beginning to look like I need to follow my dad's plan. In the 80s he was a big fan of the AMC Pacer (Well was an Eagle fan first but moved on to the Pacer). He had 3.5 Pacers, so that when something wasn't working he could swap parts from one to another to find out what wasn't working. But the key was that at least at some point the 3 fully assembled Pacers did work. The 0.5 one, well that was really just a pile of potential spare parts.