AnotherOldJeepGuy

Took a 13 mile run around the area, no highway driving so lots of start stop. I guess it was a K-12 education. Kindergarten through Grade School was pretty rough. Couple stalls, a few more coaxing to not stall, questionable acceleration. Junior High was also troublesome but maybe a bit better, transitional years I suppose. But by the time I progressed through High School things did seem to be improving, and by graduation I was able to come to a stop and start up again without it wanting to stall. So fingers crossed. I'm gonna head out for a higher education run in a bit and see how that goes, perhaps I might even get on the local highway if we make it to Grad School.

So I don't have that, but I have essentially replaced that in this instance with a flashlight and vision by watching the EGR ROD, and seeing that there is a 1:1 correlation between the 3%-5%throttle stutter and the moment the rod moves.

Just in case, I looked out there for availability of a new EGR valve. Didn't find it at Auto Zone, O'Reilly, Napa, Rock Auto, Summit, Advance or EBay. (Although everyone seems to have the gasket).

OK I'll try leaving the EGR valve hose connected for a bit and cross my fingers an ECU education is what is needed at this point. Just for clarity, the problem is at 3%-5% throttle, no problem at idle (0% Throttle). In my words, EGR "activated" means the EGR valve shaft/rod is no longer at rest and has moved outward from the engine. I do have terminology issues sometimes with my limited STMD

No idea where I can get a test known good ECU. If I leave EGR connected I have to deal with stalling at 3%-5% or at least trying to, did you mean to say leave EGR disconnected? No stalling with EGR disconnected.

OK here's that data! Some of the number do move around which seems appropriate, so best I can do it try to capture the range. First, back on June 8 those reading were: 6.9ms, ST 135-154, LT Locked in at 128 - These captured at idle. Things that have been changed since then are: - clean grounds at the oil dipstick brace mounting bolt - reset ECU (disconnected battery) a few times - executed ECU relearn procedure - drove 15-20 miles with EGR disabled - cleaned all the injector harness connectors and injector electrical contacts - replaced low resistance arc-ing spark plug wires with OEM resistance wires that are not arc-ing (it was not a goal to get higher resistance wires, just a goal to confirm different wires would not arc) - checked distributor indexing - replaced crumbling/leaking exhaust manifold to pipe "donut" gasket. - verified TPS linear output throughout throttle (with REM readout) - re-cleaned IAC although it did not look dirty. Today, with EGR control hose still capped of, so, no EGR activation: At Idle, 7.3ms, ST 128, LT 130 (This was right after first start up of the day so engine cool) At Idle, 5.4ms-6.3ms, ST 120-145, LT 130 (This was after idling for 3-4 minutes) At 3%-5% Throttle, all of these stayed essentially the same. Today again, but with EGR control hose reconnected and EGR activation At Idle all the numbers essentially the same (no difference in how the engine sounds) At 3%-5% Throttle and with RPMs dropped due to EGR activation: PW stayed essentially the same and LT remained 130 ST dropped with RPM drop. I did not let it stall only let RPMs fall noticeably, ST was as low as upper 90s My STMD (Shade Tree Mechanic Degree) doesn't give me the knowledge to know if any of that says anything useful. But I have to wonder, if the ST went up instead of down as I hit 3%-5% throttle and the RPMs began to fall, would that be good or bad? I also have to wonder why the PW didn't move right along with the ST numbers when the EGR caused the RPMs to drop, seems l like the ECU, if it understood the RPMs were falling, might adjust that too? I have just enough knowledge to be dangerous, but not enough to know what to do with said knowledge

For sure! I'll get out there in the morning before the Texas heat kicks it!

Probably put on another 15 miles today across a few smaller errand runs. No stall, no hesitation, idle not perfect but close. All local street driving so mostly 40-45 MPH with lots of starts and stops at traffic lights. EGR still disabled. I don't like this fix, it wasn't necessary to have the EGR disabled before so something is not quite right, but after close to 3 months of effort to get a 100% fix, I may be forced to accept this repair since it seems to be a working solution (knock-on-wood) with only a small band-aid. @Gojira94, you might be getting you loaner back before too much longer!

Sorry, I used the incorrect wording. I didn't "delete" the EGR, I "disabled" the EGR by capping off the control hose as noted in the pic. Since doing that I have driven around the area maybe 5 miles or so in basic traffic, no stalling, no sputtering or hesitation. This is only day 1 of this EGR Disable experiment, so not drawing any conclusions on my end, just noting how the first 5 miles went.

I don't see this happening much. At idle with AC off it I see 120-122 and it isn't moving constantly. With AC on it bumps up to 123-125, but in both cases it stays within a couple and is not jumping around. This is probably not what is meant by continues to rise of fall. I went back to the EGR delete config because I had notice back around May 21 that the EGR plunger moves sometimes at accel, and sometimes it doesn't. And I also noted at that time, when the plunger does not move, the stalling at 3%-5% throttle didn't happen, OR, it seemed to happened way less. Now that I have possibly corrected some issues, I decided to go back to this again and with minimal testing, I am not getting any attempted stall at 3%-5% throttle. The HAS to be a clue of some kind, ether the fact that the EGR only moves sometimes, or the relationship between it moving or not, and it stalling or not or both. So, I think I'll leave it like this for the moment and see how long it will continue to not stall. Also worth adding as a reminder (and for the folks that understandably don't want to go back and study the entirety of this very long diagnostic thread), shop #1 told me the EGR solenoid was bad and it has now been replaced. Why would the EGR move sometimes rather that always at initial throttle movement? It was previously noted here that the EGR "operates at part-throttle conditions", that sounds to me like it should be moving every time I hit the throttle not just sometimes. Of course if it did, I would stall almost everytime and that doesn't make things any better, but the question still seems valid.

Before pulling the new TPS I monitored it with the REM as I very gradually increased the throttle, and it seems to be working perfectly. See the video starting at about 11s, I increased from 0 to 100% throttle as consistently as I could, and I don't see how it could be working any better, as long as a linear response it expected. https://drive.google.com/file/d/1eOZWdCA8HX7o_pE6bi6GLOq3v5kk8PqL/view?usp=sharing I think I'll take a look around the web to see how to test my IAC.

Yeah might as well try the old TPS. I see that a new IAC is not very expensive so might try that also unless the TPS turns out to be a fix.

I went with video instead. This 43s video demonstrates the "want to stall" state a few times, the most noticeable instance near the end. https://drive.google.com/file/d/1FJgFQBm6sbe5DL0OHUJR9BRpVZYLkjcQ/view?usp=drive_link As a reminder, this video is the original before any of the work has been done, or at least before most of it had been done, https://drive.google.com/file/d/1y7lS4y-ZxsylCh9y-odN4-UIrnIeS3lh/view?usp=sharing

It does start fine and idles fine when I start it. It might cycle up/down at idle a tiny bit but it is not much. It's just when I advance the throttle just a smidge, it wants to stall, that's my guess at maybe a 3%-5% throttle. Once past that spot it seems to be running pretty well again, until I approach that same spot on decel, and when it gets down there it again wants to stall in that same small window, but if it get past that to 0 throttle without stalling, it goes back to idle without stalling. It's really that 3-5% spot right now that is problematic. I'll hook up the REM and see if I can identify an RPM range that is a problem and report back. I cleaned the TB and the IAC thoroughly maybe around 18 months ago, it was stalling when I came to idle at a stop sign or light. With this new issue I have inspected both to see if they were dirty again, but both are clean. In fact cleaning these is what fixed it at that time. Back 18 months ago when I was battling a stall, and before I cleaned the TB and IAC, I installed a new TPS because I had one. Nothing changed but I left the new one in. I kept the old one, I might put it back in just to see what happens. (I have adjusted TPS to 17% at idle based on REM reading). I did get 1 single small backfire earlier today as I took the throttle up and dropped it maybe a dozen times listening to hear anything useful.

See pics on 5/26 and 5/27 (page 5 of this discussion) for what the plugs looked like back then. The consensus was running rich. I cleaned them all and put them back in. Checked again on June 15 (page 9) after a lot of the work has been done and the couple I pulled that day (to allow me to do the index check) looked clean as far as I can tell, but you can tell me if you think differently? I don't know that I have the tool for checking compression but I can probably find one somewhere. It is idling pretty smooth now and other than the tendency to stall at maybe a 3%-5% throttle, the rest of the time engine seems to be running pretty well, would these other things you mentioned be an issue at minimal throttle but not be noticeable at idle and throttle above maybe 5%?

Got back from the shop with the new donut. First stall was before I left the shop . That seems to be the most noticeable issue with the engine right now. If I can keep it from stalling right at initial throttle, it runs. The tech used a tube in the ear to check for leaks at the new gasket and he was satisfied it was not leaking. It does sound better, a sign that perhaps the leak seen before at the donut is gone. I will repeat the air-vac bubble test later when it cools down. I did tell the mechanic about the other small bashful bubble leak I had seen off and on, his opinion was that if it was that small it should not cause any problem. However if I can find it my plan is to try to plug it with JB Weld. If it is really a pin hole and I can scrape it down to clean metal, JB weld should at least provide a temporary fix long enough to tell if it makes any difference. He put a small hole in the pipe near the cat and fished a stiff wire through to check for possible flow blockage. He said it seemed to him it was already vacant at this point and is essentially a straight pipe. The guy's a 30 year mechanic at a muffler shop, seems like he would know. I currently have the battery disconnected to do another ECU reset just in case it's off at the moment because it has not learned yet that the donut leak has been repaired. A Hail Mary I know, but easy to do.

I have @pizzaman09's mod on my to do list as soon as I manage to rescue my truck from death row

Wellll, I talked to him about that and the answer was he can't do it, it's against federal law:(. So for the moment at least the cat stays. He did say he would do some kind of check by poking a hole in the pipe before and after the cat but I didn't really catch what that was going to do. The ride down to the shop was very noisy since I didn't bother to reattach the pipe at the donut since they were going to take it right apart anyway, the shop is only a couple miles away. Sounded like I was ready for the drag strip!

I hear ya and thanks! I've had this thing for too many years to give up! Got my new test case spark plug wires in the mail ($6 ebay) and put them on. I wanted to test the theory that different wires would not arc and it was worth $6 for that experiment. These plug are all the correct length (11" x4 and 13.5" x2) according to figure 8-5300 in the parts cat. All wires in place, no arcs I can see in the daylight and none heard. So my $6 set of wires may be all I need. They are all I need for now anyway. I'm taking it down to the muffler shop at close of business today so they can put it on the lift and let if cool off overnight and install the donut in the morning, and probably eliminate the cat but not 100% convinced of that yet.

FWIW I have used zip ties at multiple locations for the same reason.

Well about 2 hours later and I am no where near to getting the old donut off . I did manage to get the bolts loose, that was fairly easy. And that allowed me to move the pipe enough to get some access to the donut. I thought I was on a roll and could knock the old gasket off, put a new one on and just maybe fix something. But I had no idea the old donut gasket would be made of of granite, or something about that hard! It had no interest at all in coming off. Decided the only chance I had was to remove the pipe to get it out of the way and give me as much room as possible to work, but I could not get the nuts loose just before the cat. So I guess I'll take it to the muffler shop this week and get them to do it. Probably have them straight pipe it to the muffler while they have it torn down that way if the cat is damaged and contributing to my issue, that will be gone also. The project continues...

The alternate bubble test approach suggested by @87MJTIM was useful. Back on May 31 I noted that the gasket at the bottom of the exhaust manifold where is connects to the next pipe was crumbly. At that time I did my version of the soap test which was to soap it up and start the engine. I did not see bubbles. But with the air up the tailpipe test, I saw lots of bubbles at this gasket . I don't understand really how it didn't blow bubbles the first time, but regardless of that it blew a lot of them today. I also saw a bubble in the general area of the red circle area below. This other bubble was very bashful, it didn't last and was difficult to recreate, I tried multiple times adding more soap and only occasionally I saw something. So it is there, but, it is also much less of a void compared to the gasket. I tried soap at as many other places as I could get to and didn't see any other bubbles. I'll try to replace the deteriorated gasket first and see what happens since that void is much more plentiful, and very close to the O sensor (although on the tailpipe side so i don't know how much it counts). I hope soaking the threads a few times with PB Blaster will let me get the bolts out. Worth noting, if I tried to put the shop-vac hose in to the point that it nearly sealed at the tailpipe there was a lot of push-back, and as soon as I let go it blew itself out. This tells me that there is no large leak. I could only put it in partially filling the tailpipe hole for it to stay there. That seems to be a good thing.

I agree. There's nothing about my jeep-kill maneuver 2 months ago caused my plug wires to go bad. Over the last 2 months I have fixed or improved a hand full of things from a combination of my own snooping, inputs from two local shops, and lots of help from the group. None of them logically would result from the incident. However I have seen improvement, so the thought is the more things I improve, the fewer things are leading me away from the real problem, and also that once that is fixed, all these things along the way were still needed if not as repair then as maintenance. The plug/wire discussion has for sure gone down a rabbit hole, mostly because I don't know what I don't know, so lots of question! It would appear 4 of my 6 wires wore out quickly, or were defective from the start. https://drive.google.com/file/d/1xcfAGNxF7kxNITGvatwoXsNuFASuBCHK/view?usp=drive_link Does this combination of plugs/wires pass the test?: https://www.summitracing.com/parts/cpn-404 https://www.summitracing.com/parts/tay-51048

Interesting. I have been trying the bubble test but have been doing in letting the motor as the bubble blower. But my version only gives about 1 minute before the metal gets hot and evaporates the liquid. This seems like a good experiment to try.