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Engine swap vs shop

Do you have a spare Crank Position Sensor? -- If you do try it

No signal from the CPS will activate the Auto Shut Down -- fuel pump will still prime but then be shut off along with no spark

On my Cherokee, whenever I've had problems I can't explain it's always been the CPS -- I keep a known good spare around to save me from chasing my tail
 
Like I said -- a bad CPS will give the symptoms you have

Do you have a fuel pressure gauge? We know the system primes, which it would do with a bad cps when the key is turned on. But does the system hold pressure when cranking? I'm not even sure this is 100% going to work but worth a try -- If no signal from CPS then ASD relay activates and shuts down the fuel pump -- not sure if you would be able to read the pressure drop or not though -- if there even is a pressure drop without the engine running

Like I said, easy enough to do and worth a try if you have the pressure gauge

There may be a more positive test for the CPS but I don't know what it is.
 
I had the same symptoms a month or so ago... It turned out the pcm fuse was blown.... Pump primed and held correct pressure but the injectors didn't pulse and no spark.... In chasing my issue I used an AutoZone dizzy (cam sensor included) and the Jeep barely ran after I replaced fuse. I put original 400k mile dizzy and cam sensor in and I'm back in business... Just something easy to check

Sent from my SM-G950U using Tapatalk
 
I'm uncertain, the distributor got indexed 3 times, I rechecked grounds, removed coil, tested, reinstalled and had spark. I'll be pulling it again tomorrow and re testing in warmer temps.
 
Here's a trick to try in case the engine is not being properly grounded with the grounding cables/straps somewhere. Connect a jumper cable to the ground terminal (negative) of the battery and connect the other end directly to a starter mounting bolt, which is also the engine ground. See if that eliminates any Codes or improves the TPS voltages.

Best regards,

CJR
 
On 20v dc I'm getting .71v resting/idle, 3.90v at wide open throttle. It needs to be higher than .26 and lower than 4.49v so it seems good for sweep, volts increase/decrease smooth. The ground had .013 on run, also good. 5V read 5.18, I assume this is good?

I can try your idea CJR, but why would the ground have to do with the system running too lean? If it is ground related am I testing between wire and battery?

If it helps It didn't idle poorly until it was warmed up, should I suspect 02 sensor?
 
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The computer needs precise voltage signals from its sensors to make correct decisions for running the engine properly. Degraded sensor voltages, caused by poor grounds, are interpreted by the computer as malfunctions supplied to it by its sensors. The computer has no way of knowing the engine has one or more bad grounds. The computer only receives the sensor voltages and then makes a decision to run the engine.

The trick I mentioned ignores all the grounding cable paths and grounds the engine directly to the battery. If the sensor voltages now become normal, you have a grounding cable/ground path problem somewhere. At that point, you keep refreshing the grounding straps or add more grounding straps until you see the sensor voltages improve to their spec'd values.

Best regards,
CJR
 
I tried the jumper cable grounding trick, starter bolt to the battery negative. She's still sputtering once warmed up.
1mjrwkt.jpg
(warmed up)
yeM141W.jpg
(at start up)
Refocused these issues to it's own thread.
 
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She breathes Rocky mountain air again. This has been no small task for the inexperienced me, none the less mostly alone labor wise. Though, I'm plenty glad I haven't taken this to a shop for the insane price of the work, 5,000-6000$ in Colorado for most places I called. An engine swap is costly, tideous, and time consuming either way you go about it, shop or not. Depending on what route one is to take, I did like the ability to have eyes on and study which parts I thought ide like to replace. A shop i dont think will quite do this in your favor because you will either coin out for a damn good replacement, or you will choose a more economical route, either way the shop will want as much$ as they can score, and they will want your vehicle out of the shop asap.

All said and done I've currently forked out under 2k for engine, header, plugs, fluids, paint, cap/rotor, gaskets, new hardware, upstream 02, likely a tps mopar for the remaining p0122 code. P1391 and new CEL pending scan, p1391 was listed as unconfirmed on bluedriver.

This has been good on the wallet comparatively, but in no way has this been a process to save time, at least for a newb like myself. The forums always say "try reading". I wish this was always the solution for those of us that are trying to dig through jeep issues. There are Many many threads on topics that pertain to all kinds of issues. In the few months I have been working through this swap and trouble shooting, ive learned and read that much of what is started on threads, never concludes nor adds a resolve for said issue.

To those pondering as to if you should attempt this project, I say go for it, so long as you have no time constraints. It's manageable alone, I removed the engine/ installed alone. It will take time and lots of up/down crawling under the jeep haha.

The installation portion of my project is now over, the engine is in, the jeep runs, and I have driven it.
The jeep ran fine before this project and everything worked perfectly fine. Upon install there have been many hurdles that kept arising and more continue to, even after using know good parts. This project has had no start issues, broken bolts in the block, distributor issues, poor running issues ( https://www.naxja.org/forum/showthread.php?t=1153110 ) and currently on another thread transmission issues ( https://www.naxja.org/forum/showthread.php?t=1153278 ) The hurdles continue, the project continues in a new portion of the drive train, and a p1391 code that the blue driver has not confirmed (driving has been smooth) though I did get a CEL tonight that I need to scan in the morning ( cps,ckps are 1yr old Mopar)
This thread isn't as clean and clear as I imagined from the start, but perhaps this is for the better, for those that may want to swap engines and can see that nothing is guaranteed, any issues can arise.

To those of you that have helped with giving your knowledge and advice, And your tolerance as I've been loosing my lid through this whirlwind, I Thank You Greatly! It is easy to forgot how some answers to small questions go a long way for some of us still learning about these vehicles, and that help is appreciated immensely.

After reading, reading, reading, asking?, reading, asking?,reading and hitting a dead end, some of you out there have time spent knowledge that reading just cant replace.

* I owe a Very humble special Thank You! to Hypoid for helping me to this point. You Sir are responsible for making this possible and my hats off to you.
H0y7J2t.jpg
 
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