Need someone with obdii scanner/ help get her started

[4x4JeePmaNthINg]

New engine in, getting no spark from ignition coil and I have a check engine light on.
All grounds clean and tightened, I can capture pictures if it helps.

Ide hope a scanner will point me on where to look at least.

Thanks for any help,

Matt

[Jim]

Good progress on the engine swap!

Sorry, I don't have one.

Does the local auto store loan them out or do you need to drive up for them to use theirs?

[open_circuit]

I keep a $15 scanner in my vehicles. Would recommend borrowing from Autozone or Advanced Auto Parts -type place if you need it now. Would gladly loan to you, but I'm no where near FoCo.

[Java]

use your key:

https://www.quadratec.com/jeep_knowledgebase/article-24.htm

[4x4JeePmaNthINg]

The key trick is for newer models I believe as it's never worked on mine. Unfortunately auto zone and the like a do not loan scanners.

[ColoJeeper]

Harbor Freight offers them fairly cheap and usually interface with your cellphone.

[4x4JeePmaNthINg]

Got a bluetooth scanner from a friend. Is there anyone here that can help get their hands dirty on getting my jeep running again, I need someone that knows what they are doing, or anyone that might be a good contact to ask? I'm beyond what I know to do at this point.

Thank you

[Jim]

I'm no OBDII wizard but I'm capable enough. I'd be happy to stop over to see what can be done.

Gett'n spark... Is spark in time... Gett'n gas...

[JandDGreens]

I was wondering if you got the engine from a similar year and don’t need to change the ecu?

[Jim]

Do you hear the fuel pump spin up when the key is initially turned to RUN? Do you have fuel / fuel pressure at the rail?

This is still coil and distributor spark, yes? Is the coil getting 12vDC? Is the coil "giving spark"?

Is the crankshaft position sensor the same between the two motors?

[Getaklu]

A big question - what code or codes are being thrown?

[4x4JeePmaNthINg]

P0122 throttle position circuit a low. I haven't read anything that says this will prevent starting.

[Jim]

Do you have a multimeter?

This might get things close:
https://troubleshootmyvehicle.com/jeep/4.0L/tps-multimeter-test-1

[Getaklu]

If the reference voltage is not there, it may well be affecting other items which in turn are keeping it from starting.

[xaza]

Got some questions, how did you test for spark? Did you confirm fuel pressure in the rail? How did you set the distributor? Make sure you are at top dead center on intake stroke not exhaust stroke. The engine is cranking?

[4x4JeePmaNthINg]

Im happy to answer them. The engine is cranking. The distributor was indexed using the toothpick trick/ aligning the holes on the spindle and housing. Top dead center is indicated by lining up the harmonic balancer notch, with the notch 0 on the timing cover, which I did. I have not put a fuel pressure gauge on the rail, but the pump primes every time and I bled fuel from the rail just to make sure it was making it there. I tested for spark from the ignition coil out with a test light.

I do have a multi meter Jim, I'll review the article.

[Hypoid]

Top dead center is indicated by lining up the harmonic balancer notch, with the notch 0 on the timing cover, which I did.No mention of the compression stroke.

The notch lines up at the end of the compression stroke and the end of the exhaust stroke. It is very easy to install 180* out.

[Jim]

So... easy test is to index dist 180deg and hit the key!

[4x4JeePmaNthINg]

No mention of the compression stroke.

The notch lines up at the end of the compression stroke and the end of the exhaust stroke. It is very easy to install 180* out.

Will the rotor still line up to the 5 o'clock position on both compression/exhaust stroke?
How will I know which stroke it's on so that I turn the crank over to the compression stroke?

[Jim]

Will the rotor still line up to the 5 o'clock position on both compression/exhaust stroke?

No. Camshaft and distributor should be turning at 1/2 the speed as the crankshaft. Crankshaft will make two revolutions (4-cycle engine) to one revolution of camshaft and dist.




How will I know which stroke it's on so that I turn the crank over to the compression stroke?

In my mind (let's see what others say)

1) If you have the camshaft cover off you can see valve operation (#1 intake & exhaust valves closed on compression and power strokes).

but you likely have the camshaft cover on, with nice sealant and a fresh gasket and you don't want to pull the cover just to see valve operation so I'd

2) Pull the #1 spark plug and index the motor (starter motor or wrench crank on the cranshaft pulley bolt) and notice compression (thumb or finger sealing spark plug hole for #1) pushing your finger out of the way - that's the compression stroke - just after that stroke would be the power stroke and your finger would be pulled towards the spark plug hole.

(or just index the dist 180 degrees and hit the key)???


What say others (am I off base)?

[Getaklu]

2) Pull the #1 spark plug and index the motor (starter motor or wrench crank on the cranshaft pulley bolt) and notice compression (thumb or finger sealing spark plug hole for #1) pushing your finger out of the way - that's the compression stroke - just after that stroke would be the power stroke and your finger would be pulled towards the spark plug hole.

That is what I would do to find the compression stroke.

[4x4JeePmaNthINg]

http://i.imgur.com/PlXO4VF.jpghttp://i.imgur.com/WwBeBqF.jpg

Now correct me if I'm wrong, but my research led me to understand that when indexing the distributor, I should have the balancer at 0 and the rotor pointed to 5 o clock, this being the compression stroke. If the rotor was facing 10, then it would be on the exhaust stroke??? Unless I'm incorrectly looking at how the rotor is pointing.

[Jim]

my research led me to understand that when indexing the distributor, I should have the balancer at 0 and the rotor pointed to 5 o clock,

This is Mike's position - you need to ensure you're at Zero / 0 on the crankshaft pulley ON THE COMPRESSION STROKE as it can be at zero / 0 but be on the exhaust stroke. If the crankshaft is at zero - but on the exhaust stroke (the wrong zero), no matter what you do with the distributor - it'll be wrong.

[Patrolman]

No mention of the compression stroke.

The notch lines up at the end of the compression stroke and the end of the exhaust stroke. It is very easy to install 180* out.

Agreed. I have helped more than 1 person with their distributor, which just turned out to be 180 off.

There are several different tricks to do this, some take an assistant.

1) pull the valve cover off. rotate the engine until you are at o degrees and both valves on #1 are closed
2) put a wrench on the crank bolt to manually turn it. Pull #1 plug. Put your thumb over it while the engine is being turned over. You should feel the compression on your thumb since you won't be able to hold back the PSI on the compression stroke. When it is at 0 on the pulley, you are at TDC.
3) thread in a compression tester. Similar to #2, you will see the needle move up when you are on the compression stroke. Stop at 0.

Hope that helps!

[JandDGreens]

Oh I remember pulling my distributer out with out marking the location. What a nightmare trying to find the right spot to drop it back in. I hope that once you get it right she fires right up.

[4x4JeePmaNthINg]

I'll check as soon as I can, 12hr shifts don't make progress easy haha

[Hypoid]

2) put a wrench on the crank bolt to manually turn it. Pull #1 plug. Put your thumb over it while the engine is being turned over. You should feel the compression on your thumb since you won't be able to hold back the PSI on the compression stroke. When it is at 0 on the pulley, you are at TDC.The only caution to this method is the exhaust valve is still closed at the start of the exhaust stroke. As the crank rotates, you will feel pressure build, until the exhaust valve opens. That is part of the reason this mistake is easy to make.

[4x4JeePmaNthINg]

Perhaps I'll rent a pressure gauge just to make sure I got it turned over to where I thought air was coming out a good ways after the mark on the timing cover, that's as far as I got before I had to leave for work because my spark plug fell conveniently between the alternator bracket and the block, so I went fishing.

[Jim]

What's the gallery think about this: Pull the dist and rotate it 180 degrees from where it currently sits. Any harm in trying - no issues with a backfire causing problems?

My thought is that this change might be a quick and simple test.

[xaza]

What's the gallery think about this: Pull the dist and rotate it 180 degrees from where it currently sits. Any harm in trying - no issues with a backfire causing problems?

My thought is that this change might be a quick and simple test.
I was thinking the same thing but something else is concerning. He tested with a light from ignition coil and is getting no spark. I would get the spark first then worry about timing. Here is a link how to test ignition coil.
http://www.fixjeeps.com/jeep-ignition-coil.html

[Jim]

I tested for spark from the ignition coil out with a test light.


He tested with a light from ignition coil and is getting no spark.

I went back to re-read - first time through I took this as there was coil-spark - but now, I don't see it saying either way. So, Matt, is there spark from the coil?

[4x4JeePmaNthINg]

What's the gallery think about this: Pull the dist and rotate it 180 degrees from where it currently sits. Any harm in trying - no issues with a backfire causing problems?

My thought is that this change might be a quick and simple test.
If the new one time around revolution ive done with the crank is on the correct compression stroke, then I will have to re-index the distributor, because the rotor is now pointing to 10 o clock.

[4x4JeePmaNthINg]

I went back to re-read - first time through I took this as there was coil-spark - but now, I don't see it saying either way. So, Matt, is there spark from the coil?

There is No spark from the coil from my test light. I don't know if there is any validity to this, but a work friend thought test light directly to the coil would be too much voltage to indicate spark and that I may want to try a spark tester/ screwdriver in the plug and look for spark to another piece of metal.

[Jim]

Spark from the coil:

There is no concern for too much voltage direct to coil.

If no spark from the coil - Cliff's on point - this is an issue that needs to be tended.

You're doing this coil-spark test via cranking the motor with the coil and ignition system fully connected (12vDC power to the coil as well as trigger to the coil), yes?

An option is to connect a spark plug to a plug wire. Ground the plug in a spot where you can visually see the plug's gap (see a spark jump the gap). Plug the other end of the wire into the coil. Ignition to on and try to start the engine. You might need an assistant / depending upon where you can mount & ground the plug. Do you see any spark when you try to start the motor?

[JandDGreens]

There are several sensors that directly affect wither you get spark or not. One is located under or near the battery tray. If that is not connected or goes bad you won't have anything coming out of the coil. I don't remember what it's called Mark had a issue with that one. Crank sensor, there is a couple others. Would think if you had a running engine before the swap that they wouldn't be the source but I would pull and use a electrical cleaner and dielertric grease for the connector plugs (ie; water crossings) to insure those aren't the problem. Corrosion in any of the connector plugs might cause no spark.

[4x4JeePmaNthINg]

There is a heat sensor in the battery tray, but that's the only one near it that I know.

Anyway the to do list thus far is:

Check distributor index and tdc with a gauge

Check for spark from the ignition coil, or rather the wire from it

Check for key on 12v to the coil
Feel free to steer me in the right direction if I'm not on track, I really need to get this vehicle running.

[4x4JeePmaNthINg]

She running now, however I have two codes.

P0122 TPS circuit A low voltage
P0171 system too lean bank 1

Both 02 sensors are Bosch, aftermarket before the swap. So is the fuel pump. I'll rent a fuel pressure tester.

Any thoughts on what to check?

[Getaklu]

https://www.obd-codes.com/p0122

https://www.obd-codes.com/p0171

[Hypoid]

She running now, however I have two codes.

P0122 TPS circuit A low voltage
P0171 system too lean bank 1

Both 02 sensors are Bosch, aftermarket before the swap. So is the fuel pump. I'll rent a fuel pressure tester.

Any thoughts on what to check?
The TPS fault can cause the O2 code. Time to troubleshoot the Throttle Position Sensor input, output, and sweep.

[JandDGreens]

Congrates! Some progress. Now you can get it tuned and ready to rock-n-roll.

[Jim]

That's great progress!!

...but I'm scratching my head - what did you change from no-run to run? It seemed like you weren't getting spark...

[4x4JeePmaNthINg]

Your question is valid, idk really. I re indexed the distributor for the 3rd time. I had a good laugh once I found i struggled this last time from using the 2.5 guide hole instead of the 4.0, the other times were far easier when done right. removed and cleaned grounds again. The CEL disappeared and now these other codes exist.
I had pulled the coil to test last week after no spark with the test light.( im still uncertain if a test light would be worked for high output), reinstalled the ignition coil and tested spark with a plug, which it had this time.
I'm going to remove the ignition coil again and re test it in warmer conditions, I'm not so confident that it is 100% ok.


Now to tear into the TPS again, it's running, but I'm not out of the woods yet.

[4x4JeePmaNthINg]

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.

Now I'm lost, any ideas?

[Jim]

I don't know TPS's much - but when mine went it seemed to have a "dead spot". Is yours consistent (gradual change from low to high) with voltage through the range? It doesn't have any drop or spike through the range?

[4x4JeePmaNthINg]

Yes it's smooth, I'm trying two more tests that I've read about. On pins1&3

[JandDGreens]

Anything new to report?

[4x4JeePmaNthINg]

Ha, right now this thing is whipping my butt. She idles fine until at operating temp, then starts sputtering terribly.

[Jim]

How much is a TPS? (just replace it and cross fingers) If mine's the same you could borrow it for testing.

Strobe light shows timing is correct, yes?

[4x4JeePmaNthINg]

Haven't used any strobe deal?

I don't understand how it runs fine until warmed up. Can you rent a timing strobe and what should it read? I believe Mopar TPS is 87$ ish, 02 ntk brand 35$. I'm going to attempt a vac leak test with propane and a diy smoke machine test also for vac leaks.

Another jeeper asked if a tooth on the distributor could be off, I don't think it will fit the retaining clip if it were, would it?
O2s are Bosch and were replaced few years ago, others say these don't work well in 4.0s??? Hypoid, they read, but obviously there's something not right vac leak or other.

Cap, rotor, napa echlin new, New plugs Autolite APP985 4.0 recommended, injectors are BWD 4 hole they were bought new a few years ago and ohm test good. Fuel pump Bosch few years old.
IAC,MAP stock
TPS napa I think, it's my 3rd,
Likely to put Mopar in just in case.
Throttle body stock with fel-pro gasket
New motor with banks revolver header & gasket, 99 intake

I'm try I'm trying these tests and inquiring for more knowledgeable hands on help to get this thing running. Ill pay my way to get my wheels back, please P.M. me if yiur quite confidant we can fix this.I need this vehicle back on the road, it's currently in my garage and ide Really not like to tow it somewhere.

I'm humbly for diagnosing anything I'm not considering, keep throwing ideas if you all have them.

Thank you all very much

[Hypoid]

I'm going to attempt a vac leak test with propane and a diy smoke machine test also for vac leaks. I plan on bringing a vacuum gauge. "Old school" physics still apply to newer engines.

Another jeeper asked if a tooth on the distributor could be off, I don't think it will fit the retaining clip if it were, would it? Typically, these engines won't even start if you are off by a tooth. I have read about one that did start, and barely ran.

O2s are Bosch and were replaced few years ago, others say these don't work well in 4.0s??? Hypoid, they read, but obviously there's something not right vac leak or other. The sensor in the header runs the fuel management. the sensor in the CAT just sets a light when the CAT goes bad. That said, let's not throw out the baby with the bathwater.

Cap, rotor, napa echlin new, New plugs Autolite APP985 4.0 recommended, injectors are BWD 4 hole they were bought new a few years ago and ohm test good. Fuel pump Bosch few years old.
IAC,MAP stock
TPS napa I think, it's my 3rd, That is odd, do you have hood vents?
Likely to put Mopar in just in case.
Throttle body stock with fel-pro gasket
New motor with banks revolver header & gasket, 99 intake I'll bring an inspection mirror, to check the underside.

I'm try I'm trying these tests and inquiring for more knowledgeable hands on help to get this thing running. Ill pay my way to get my wheels back, please P.M. me if yiur quite confidant we can fix this.I need this vehicle back on the road, it's currently in my garage and ide Really not like to tow it somewhere.

I'm humbly for diagnosing anything I'm not considering, keep throwing ideas if you all have them.

Thank you all very muchI hope to make the trip this Tuesday.

[Jim]

Mike's on it!

If you wish my hand or any tool I might have - willing to assist.

[4x4JeePmaNthINg]

No hood vents mike, first tps went with the event I'm believing to taken the first motor out, threw a cheapo replacement on to get it started back then. Cheapo got wet and instantly wasn't having it so I put a napa one on a couple years ago.

Is there anything you would want me to have on hand Mike?

[Patrolman]

Congrats on getting it running. Sounds like significant progress!

[Hypoid]

Is there anything you would want me to have on hand Mike?Is that garage heated? If not, I'll bring a space heater.

[Jim]

I have a 60K BTU kerosene unit avail...

[4x4JeePmaNthINg]

No but I have one of those two dish looking propane heaters

[Hypoid]

I have a propane heater that looks and sounds like a jet engine, and a lot of propane. Won't hurt to load them also.

[4x4JeePmaNthINg]

No complaints here haha, were just lucky it's not minus whatever out tomorrow!

[Jim]

`curious to what happened...

[4x4JeePmaNthINg]

Well Jim. I don't want to muddy Mike's follow up. He was very thorough and we found a lot of interesting information. I will say she's running! BUT I tried to move her just now and I heard a buzzing from the transmission while shifting back up to park. Fluid was low so I topped that off once at temp. I tried shifting twice before checking fluid, just ran through the gears as it was running. After,
I adjusted the kickown cable, but I don't know what in the world this noise is!!! Haven't tried after adding fluid, I need info lol. Ugh this never ends, if only ide have thought of trying to move her while you were here Mike, you KNOW your stuff!!! I can't thank you enough for the help and the knowledge base you just can't read about, it comes with years turning the wrenches!!!.

Thank you again Sir.

Ideas? I do Not want to damage anything. Perhaps I've missed a step after reinstalling the trans shift linkage??

I have looked as close to the bell housing as possible, I can't see anything binding, but I can't see the very top either.

[Hypoid]

`curious to what happened...
I'm writing a novel, after school tonight. :lmao:

[4x4JeePmaNthINg]

What do you all think of this P-R clunk:
https://youtu.be/ISuEyxziVvI

Kickdown adjusted, fluid topped. It's an audible clunk. Yesterday was a buzz before adding fluid and kickdown adjustment. Is this the trans trying to get fluid back in it?

[Jim]

What do you all think of this P-R clunk:

Do you have your foot on the brake when shifting?

Is the rear axle jacked up / can the rear axles rotate while the vehicle is stationary?

[4x4JeePmaNthINg]

Yes foot on the brake, no rear drive shaft in, I'm going to push the t case lever all the way toward the front of the jeep and see if that's 2wd.

[4x4JeePmaNthINg]

I found 2wd and the output does spin. I did get that buzz again in R, while shifting from D-P.

[Jim]

I wonder if the buzz is the parking pawl trying to engage while the mechanism (output end) is still spinning.

If you don't have (either) driveshaft installed, the output ends of the transmission have nothing to stop them from rotating, aside from waiting in neutral for them to stop spinning, before going into park. It's similar to trying to slam into park when you're moving at 1 to 5 mph...

I think, if you had the full drive train installed - where the output couldn't free-wheel (foot on brake would cause trans output to be not-rotating) you might not be getting these noises.

(I should re-read the posts to see where the noises are happening)

[4x4JeePmaNthINg]

I'll give it a try jim, only missing the tail shaft. Easy enough to throw on and test on my weekend.

[Hypoid]

I'm writing a novel, after school tonight. :lmao:
It took longer to write, that it did to execute. The purpose of writing this out is to illustrate a systemic approach to diagnostics, that seems to be absent from many internet threads.

First and foremost, I want to give a shout-out to Matt. He did a great job on the many "first time ever" tasks that went into this engine swap!

Drill-Down List:

Visual Inspection:
All electrical and vacuum systems hooked up, general condition?
Any loose or missing fasteners?
Any gaps, misalignments, or witness marks indicating loose assemblies?

Confirm Observations:

Matt had already confirmed the TPS Low and High Voltages were within prescribed limits. Without having specific knowledge of the software’s terminology, I wanted to do a “sweep” test on the sensor. Having some working knowledge of Rheostats and Potentiometers, and not having a DVOM with the capability of measuring for “drop out,” I brought an analog Ohmmeter. Alas! I could not reliably connect to the pins, so we opted for the OBDII reader. With the Key On, Engine Off, we checked the TPS for dead spots. The display did show two spots with no reading from the TPS, but, not at idle. The question remains: Are the dead spots the reason for the “TPS Low Voltage” code?

Since I am not familiar with the scanner software, I wanted to take another approach to the “Bank 1 lean” code set by the scanner.

While we tested the TPS, the ECU set another code, something about no signal from the CPS. Go figure!

Active Investigation:

After attaching a Vacuum Gauge to the manifold, and pressure gauge to the fuel rail, we started the engine. I noticed a slight misfire, and rough idle. The vacuum gauge registered 14” at idle, with minor, rapid, fluctuations. I thought this was a low reading, which could be an indicator of a few different problems. There were no sounds indicating mechanical problems inside the engine. I attributed the rapid fluctuation and low vacuum to the cylinder misfire. Fuel pressure was within spec, and consistent.

In an attempt to track down the misfire, we started by disconnecting the plug wires, one at a time, with the engine running. Each time, the rpms dropped, with no other changes. I touched each injector to find the solenoids cycling. In spite of Matt’s diligence in labeling and keeping the under hood organized, I wanted to try swapping injector connectors on cylinders 1 & 2, 5 & 6: No change. When we shut off the engine to swap the first pair of injector connectors, I did monitor the pressure on the fuel rail. After waiting 30 minutes, we had a slow and consistent 50% bleed down, which I believe is acceptable.

Through my process of looking for the big AHA! The scanner software on Matt’s had shut off a few times. At this point, I wanted to see the real time output from the oxygen sensor. Matt found the bar graph, with a voltage reading. As we watched, the graph went flat, the voltage went to zero, and stayed at zero. We had our smoking gun! When Matt pulled the oxygen sensor, it was covered with black soot.

After installing a new oxygen sensor, we started the engine to record the same low, unstable vacuum reading that we had already documented. I held the throttle open long enough to clear unburned fuel from the cylinders, no change. Time to look at the spark plugs.

http://www.frontrange4x4.com/forums/attachment.php?attachmentid=48625&d=1552237484

All six spark plugs were covered with black soot, except where the arc was jumping from electrode to ground strap. All six plugs were properly gapped. All six spark plugs are platinum tipped, the manufacturer specified standard plugs. I wanted to do a compression test while the spark plugs were out.

Matt held the throttle all the way open while cranking the engine. While cranking on the first cylinder test, there was a strong fuel smell that was not present when we tested the rest of the cylinders. Results are as follows:
Cylinder 1-130 lbs.
Cylinder 2-130 lbs.
Cylinder 3-128 lbs.
Cylinder 4-135 lbs.
Cylinder 5-132 lbs.
Cylinder 6-130 lbs.

After recording the readings on my phone, I observed that all cylinders held their pressure until I released it.

At this point, we decided to install the used plugs from the old engine. We pulled the used plugs from the old engine, verified the gap and installed. The engine started easily and idled smoothly, the vacuum reading was more stable at 14”. As a cross check, I put the vacuum gauge on my engine: 14” vacuum. I guess that is all we can expect at that elevation.




https://www.youtube.com/watch?v=cYfT3yWF2Qw

[xaza]

Excellent write up Mike. Around 14" vacuum is what I get with my Jeep. I would also pull spark plugs again in a week and make sure they are staying clean and the cause has been resolved.

[Jim]

Thanks for the detail!



All six spark plugs are platinum tipped, the manufacturer specified standard plugs.



We pulled the used plugs from the old engine, verified the gap and installed. The engine started easily and idled smoothly,


So you're putting the cause at bad plugs or a single bad plug?

[Hypoid]

So you're putting the cause at bad plugs or a single bad plug?Without more in depth research, I'm thinking the Autolite Platinum plugs are not the best product for this model year.

Now that we are focusing on spark energy, I remember watching blue sparks jump a 2-inch air gap while I was pulling wires one at a time, and doing the compression test. I think the ignition system is working as it should.

[4x4JeePmaNthINg]

Mike that code we saw we saw was p1391, it's showing again. Both ckps,cmps are about 1yr old Mopar parts. I believe we verified spark already so I'm a bit lost on what to check, except the distributor itself is the 220000 stock.

I had a new napa reman I chose not to use because the shaft play seemed the same as the stock.

Should I be looking elsewhere or is the distributor likely worn?

[4x4JeePmaNthINg]

Ok guys so p1391 CEL continues to come on, and I'm stuck, I have gone through every step of FSM check and youtube video that pertains to this.

I have tested all continuity from PCM to each lead on the harness for ckps, cmps. Everything was within .6-.8ohm.
I have checked for 5V supply at sensor harness and PCM ( key on, key off, cranking), I've checked signal wires the same, ground wires the same.
- Cmps/ckps 5v supply
. A17/K7
. .09 key off
. 5.19 key oncc

- cmps signal
. A18/K44
. .09 key off
. 5.19 key on

- cmps/ckps ground
. A4/K167
. .0V cranking,key on, key off

-ckps signal
. A8/K24
. 4mv key off, .09 key off
. 1.7mv key on, 5.19V key on
5.26V crank
-ckps 5v supply connected to harness
. .09V key off
. 5 19 V key on
. 5.26V crank

-ckps ground (2V)
. 0V key off
.016 key on
.180 crank highest

What do you guys think?

[JandDGreens]

Just wondering? Did you get your rig running?

[4x4JeePmaNthINg]

Yes it's running, but it's got a code I have been unsuccessful in tracking down. P1391. I've tested everything I can and I'm planning on taking it to a Chrysler mechanic. There they can load test it and put a scope on it. She is moving on her own power though!

[JandDGreens]

Nice, but hope you can figure out the code. C-AIR is a pain w/the engine light won't pass.
Is it running strong? And ready for the trails? Anyway glad you've got this far!

[xaza]

P1391 is Crankcase or cam shaft sensor circuit, seems you already knew that. It is often the crankcase position sensor which can test out electrically but won't work. Cheap sensors from Autozone, O'reilly and Advance tend to be defective out of box or have very short service life. I hear Jeep is the best place to get this, $194+ tax but maybe you got a bad one. Napa is $85 and appears to have gotten rid of the code on my buddies 01 Cherokee that we replaced yesterday. Also check the wiring harness near the back of the engine to make sure there are no spots rubbing.

[4x4JeePmaNthINg]

It's Mopar sensor#2, the replacement to the stock. Hypoid suggested it not likely being the crank as he didn't think it would run. CEL on every second start after clearing. Harness ohm tested good, signal and supply tested good.
Otherwise it starts and drives fine. I really hope it's not the sensor but I don't want to go spend another $100 for a Mopar sensor and that not be the case.

That's where the dealership comes in being able to mount a scope and seeing the pattern between the crank and the cam position sensor plus being able to do a load test and readout. 115$ diagnostic

[xaza]

That's a lot more reasonable diagnostic charge than I would have expected. Can't go wrong knowing the issue for the same or less money than throwing parts at it.
p.s. When the crankcase sensor went out on my Jeep I had intermittent problems and codes for months before it finally went and would not start or run.

[Hypoid]

Hypoid suggested it not likely being the crank as he didn't think it would run.I've been reading about XJs that had problems with the crank sensor, but the vehicle still ran. So, take my opinion with a grain of salt. :redface:

[4x4JeePmaNthINg]

The ballbreaker here is I can't see how the sensors function in relation to one another, nor can I see which is possibly bad, beyond the tests I've done. So 100$ buy a sensor and maybe it works, 115$ dealer diagnostic under load and scope, then it becomes either 100$ sensor or 135$ wiring overlay, sigh.

So if I bought two new sensors, ckp, cps, I'de be at 200+ and no promise of fixing. And if that happens to not fix my issue I'm really stuck because ive traced all wires to pcm and continuity was good.
I
Ide love to know someone with a snapon scanner to read these signals so I could find out What's going on my self. I Hate bringing the jeep to a shop, never had good experiences so ide Hope the dealer would not goof around.

[Hypoid]

This thread just popped up: https://naxja.org/forum/showthread.php?t=1154226

[4x4JeePmaNthINg]

I've done most all that other than replacing sensors again and using a scope. Distributor is new now and you've heard it run, pretty safe to say timing is good. I threw out a thread on making sure I'm checking all grounds properly.

Ive done continuity, should I look for voltage to, short to ground type issue?

I can't express enough how much I DO NOT want to bring this to somone, I've been procrastinating after my last tear through with millimeters.

Thanks for the link though Mike. A bit interesting how anak responded compared to the stock of threads ive read already. Similiar layouts, but he changed some things.


I'll give it hell anything yall suggest. This is sensor or wiring. One I can't test further, the wiring ive tested good multiple times, or I've missed some detail. Either plausible.
:lmao:

[4x4JeePmaNthINg]

Update folks:
So I finally broke down and took the jeep in for a diagnostic.
The shop mechanic said the scope verified cam and crank sync, signal was getting to the PCM, it looks good other than it throws the CEL every second start.
The mechanic said with this they were 99% sure it was a PCM issue, but couldn't give 100% without replacing it.

Today I went and got a 99 PCM with matching number from the JY. https://imgur.com/gallery/PyHAD8q

Disconnected my battery, connected the PCM. Started the jeep, let it run to operating temp, shut it down , restart and CEL is back just like the old one.

At this point a couple of you thought try a new ckps. I can throw this in tomorrow if no one thinks this a poor idea after all I've tried? Other than emailing the shop back about there diagnosis not panning out, im pinned without anything else to try.

Thoughts?