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Discussion Starter #21
Today I took the injector wires off and checked the continuity on each injector to the pcm pins. Cylinders 6 and 2 were showing infinity on the ohms. Thought I had discovered my problem. After taking the wiring harness apart from the pcm connectors to the connector where the injector harness plugs into the main wiring harness, I was rather surprised how good the wires within the harness looked. The colors were still bright and the wires were not stuck together as I expected, except for a section about 8 inches long, which were mostly injector wiring wires, which were stuck together and very very rigid.

I slowly peeled all the wires apart and luckily found no torn or compromised insulation on any of the wires. I tracked the #6 and #2 wires from the connector to the pcm connector pins. What I found was that the pin printout I have has the two pins backwards. When I realized what had happened, I checked the continuity on the two wires and it was fine - I do not have an injector wiring problem.

I put everything back together and cranked the van. It started right up, which it has done before while this ordeal has been going on. Initially the engine was running rather rough. I slowly gave it gas until it reached rather high rpm and seemed to be running rather well. I let off the gas and as it come back to an idle it started running rough again. Back up in rpms, ran fine, down in rpms and rough again.

One thing odd that happened was that as I slowly increased rpms, engine running fine, there seemed to be a little "bump", but the rpms continued to climb slowly.

Turned the engine off. Started right back up and went through the same routine.

There are 3 new things: the bump as the rpms increase, there does seem to be a new metal to metal like sound (like a bearing going out) coming from the engine to the passenger side, and finally, after the engine ran there was a very black watery looking residue under the tailpipe. I don't think this is gas because I soaked it up with a paper towel and tried to ignite it - wouldn't burn.

I will take a look at the rotating flex plate tomorrow as Special Edy suggested.

Any observations or opinions would be greatly appreciated.
 

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3rd gen > all others
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I still think the flex plate needs a closer look. It will cause intermittent running issues. Checking while engine running will not reveal anything.

Best way to check is to remove the transmission, but there may be an easier way. I got one of those Lizard Cams for Christmas, basically a cheap fiberoptic camera. I wonder if the 4 torque converter bolts could be removed, then pry/push the torque converter into the transmission as far as it will go, and that would give enough room to sneak the LizardCam probe up in there for a closer look? If there were some rusty-looking dust coming from the center, that would indicate a cracked flex plate. It may be cracked but held together enough to still drive the transmission and start now and then. The more it shifts direction (starter torque to start engine, then opposite forces as crankshaft drives the converter) the more it will wear and have more and more failures/stalls until it is out of sync enough with the cam that the engine won't run at all - ever.
 

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Discussion Starter #23
Road Ripper, you may very well be right. With the van as old as it is I don't know that it is worth the cost of having a shop do the inspection - and I'm not even close to being a mechanic - so it might be approaching junk time. However, as it might be the last chance for the van, I might attempt it if I can locate the documentation on how to do it.

Although I am not crazy about replacing a part that testing shows is working, I am going to take Special Edy's advise and go ahead and replace the camshaft sensor just to "see".

One thing of note regarding parts stores. Advance Auto, Auto Zone and O'Reilley's all have about the same cost on the camshaft sensor. None of the them carry the part - has to be ordered. For me to order with Advance Auto or Auto Zone, in my case I have to drive 9 miles to the store, pay them for the sensor, they order the part, and I have to go back later and pick the part up. O'Reilleys takes a call from me and I go in when the part is in the store and pay them. 18 miles O'Reilley, 36 miles with the other two - not to mention the time.

Thanks for the comment Road Ripper
 

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Discussion Starter #24
I found an excellent 4 part series of videos which are very detailed about removing the trans on a 1998 Chrysler, which should be the same as a 1996. The video is on YouTube and it is done by Erich the Car Guy.
 

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Discussion Starter #25
Bought a new camshaft sensor and no joy - cranks but sounds like it is getting no gas or no spark or both. Late now but will look into both tomorrow but expect both will be there, just no start.

I took the old sensor out without too much difficulty - very cramped working but there is a hole through the bracket in front of the bolt which secures the sensor so there is access to the 10mm bolt. I thought by just looking at the sensor that it would just lift up off the bolt once the sensor was coming out of the engine but it will not. There is another bracket right beside the bolt which curves up and over the sensor bolting arm so the sensor will not clear the bolt to allow removal. The bolt has to be taken out and then the sensor will come out of the engine compartment fairly easily.

I put the new sensor into its hole after putting a light coating of oil on the o-ring. Pressed the sensor down into the hole, swung the sensor arm around so it could be bolted down. Then, how do I get the bolt back into the block. I wound up laying a piece of toweling paper over the socket and pressing the bolt head down into the socket, tore off the excess paper and that was enough to hold the bolt in the socket and allow me to have the bolt in the socket, in a horizontal position, and the bolt not fall out. Little tricky getting the extension through the hole in the bracket but found the bolt hole fairly easily and screwed it right in. Then I realized that the sensor was not down into the hole far enough because the bolt through the sensor arm wasn't nearly bedded enough. Try as I might, I could not get the sensor further down into the engine. I took it out.

This time, I compared the old sensor to the new just to ensure the arm/bolt hole was the same on both sensors - they were. I carefully cleaned out the hole in the engine - got all dark spots off any part of the hole going into the engine. I put a thin layer of high temp grease on the sensor, especially the o-ring. Place the sensor back into the hole and push, turned the arm into place, push more and could finally feel the last pop as the sensor sunk entirely into the hole - you cannot see the o-ring when properly seated.

Bolted the sensor down, reconnected the wiring, reconnected the battery, cranked - no joy.

The videos on taking the trans out were very good with great pictures and good dialogue on what was going on. I am going to do more research but it does not look like a job for the DIY as the video was done with a lift being used, two very fancy jacks and lowering the trans out of the engine compartment still not all that easy.
 

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Discussion Starter #26
I found the problem and I especially want to thank Special Edy, not only for the great information provided but also for the advise to not trust auto part store parts.

I was warned in another thread not to trust parts from auto parts stores. I will echo that warning.

When I first encountered the stall, no start situation I bought a new crankshaft sensor. Van still would not start. I parked the van for a number of months and then decided to fix it or junk it. Prior to the stall, no start, the van ran great and I really enjoyed driving it.

I spent hours and hours conducting test after test and just didn't find anything. I did discover the ASD/PCM relationship in a Chrysler as compared to a Buick is very different. I got to the point of checking the injector wiring harness and then the pulse to the injectors from the PCM. I discovered that I was getting a very erratic pulse to the injectors.

A very erratic pulse indicated one of two things to my very limited mechanic skill set - either the crankshaft or the flexplate (since I had already just replaced the camshaft sensor.) I really did not want to attempt to deal with the flexplate so I decided to get another crankshaft sensor (solely because of previous warnings.) I took the crankshaft sensor out of the engine and checked the omhs - not having a clue what the reading should be. Went to the parts store and got another crankshaft sensor. The new sensor showed 0 ohms. The old sensor was in the 900 to 580 ohms depending which outside pin was being compared to the inside pin. Gave me some hope.

Put the new sensor into the engine. Cranked the engine twice and it fired right up and is running great.
 

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Good to hear you have it running again and it was a simple fix.
Apparently the fuel pressure being different than the manual spec is not an issue.
 

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I called it last May:

"With Chrysler vehicles and that age/mileage, I strongly suspect a bad crank sensor. My sister's 96 Jeep Grand Cherokee Laredo would do the same thing. Multiple mechanics couldn't figure it out! I googled the symptom, and was greeted with a bundle of answers that all said "replace the crank sensor" and that fixed it. They also said don't use a cheap sensor either if you want it to last. Mechanics had put a discount auto parts store crank sensor in the Jeep, and it only lasted a year. I bought a NAPA one and it hasn't missed a beat for a year now. Not a single symptom of cutting out unexpectedly, or not starting. Heat seems to weaken the sensors over time, and they are usually located close to the exhaust routing (nice design Chrysler)."

I will add my sister's Jeep kept running until she sold it because it needed a water pump, tires, and was rusting out badly. The shop that tried fixing it replaced the battery and, in desperation disconnected the remote start/alarm system which kept her power locks from working. They never offered to reconnect it, even though it wasn't the problem.

Glad you finally got it figured out. I was hoping you were using the paper spacers with the new sensors properly. 3rd gens are such nice, comfortable vans with easy to use features and reliable when maintained. If only they didn't rust so badly...
 

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1996, 415K miles, 3.3L

Problem started with van running great but just cutting off. Normally would restart and run great again until cutting off again. Would not start after last cut-off. Sat for a couple of months and then attempted to start - no joy. Couple of days later, cranked - spit and sputter, repeated over and over and the engine started and ran great, reved to 3.5K rpm, cut off, restarted and ran fine. Dropped down into reverse and engine sputtered. Moved back a few feet, placed in D and moved forward couple of feet. Reved to high rpms again, engine sounded fine. Parked overnight, next morning would not start. In cranking there is now very loud engine side back fires, no start.

Fuel at rail. Checked with gauge at 42+ psi. Press Shroeder Valve needle and fuel will shoot 1/2 up plenum. Checked injector wires with noid light, getting signal at injectors. Can't check click of injectors because engine will not start at present. Very difficult getting to back injectors as they are buried under plenum.

Removed MAP and cleaned with carb cleaner. Removed throttle body throat, cleaned back of butterfly, removed IACM and cleaned with carb cleaner. Air filter clean. Throttle Position Sensor check with voltmeter - .89V at closed throttle, 4,5+ at open throttle, indicating it is working properly.

Fire at all cylinders. Checked Crankshaft and Camshaft Sensors with voltmeter and turned crankshaft. Both are working correctly, dropping to about .5V and peaking at about 5V.

OBDII scan shows P1391 code which is intermittent crankshaft or camshaft sensor signal. I do not have a scope to see if crankshaft and camshaft sensors are in sync.

Researching code indicates the crank and cam shaft sensors AND jumped timing chain could be causing the P1391 code. The crankshaft sensor is new. The camshaft sensor a couple of years old. Both of those sensors test as ok.

Additional research indicates that the flex plate cracking will cause this type situation as the crankshaft sensor signals the PCM based on the rotation of the flex plate, but there is very little to nothing on the internet concerning dealing with the flex plate.

I fell as though I am probably looking at a timing chain issue or a flex plate issue. Any opinions/suggestions on this would be appreciated.

Is there some way to check or test the flex plate without removing the transmission? Does the transmission have to be removed to replace the flex plate?

Any help would be welcomed and appreciated.

I say flex plate. Can be examined through the CPS hole with a video inspection cam. Here's what I found ! I had all of the above symptoms, gradually got worse until it stopped running. Replaced the plate and now runs like new. Happened at 190,000 miles! Good luck everybody.
56437
56438
 

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I found the problem and I especially want to thank Special Edy, not only for the great information provided but also for the advise to not trust auto part store parts.

I was warned in another thread not to trust parts from auto parts stores. I will echo that warning.

When I first encountered the stall, no start situation I bought a new crankshaft sensor. Van still would not start. I parked the van for a number of months and then decided to fix it or junk it. Prior to the stall, no start, the van ran great and I really enjoyed driving it.

I spent hours and hours conducting test after test and just didn't find anything. I did discover the ASD/PCM relationship in a Chrysler as compared to a Buick is very different. I got to the point of checking the injector wiring harness and then the pulse to the injectors from the PCM. I discovered that I was getting a very erratic pulse to the injectors.

A very erratic pulse indicated one of two things to my very limited mechanic skill set - either the crankshaft or the flexplate (since I had already just replaced the camshaft sensor.) I really did not want to attempt to deal with the flexplate so I decided to get another crankshaft sensor (solely because of previous warnings.) I took the crankshaft sensor out of the engine and checked the omhs - not having a clue what the reading should be. Went to the parts store and got another crankshaft sensor. The new sensor showed 0 ohms. The old sensor was in the 900 to 580 ohms depending which outside pin was being compared to the inside pin. Gave me some hope.

Put the new sensor into the engine. Cranked the engine twice and it fired right up and is running great.
I say flex plate. Can be examined through the CPS hole with a video inspection cam.
First, this thread is six months old.

Second, you don't need a video inspection cam to check the flexplate. If you have one, then use it, but don't buy one just for this, not worth it.

Third, OP solved the problem, it was not the flexplate.

Don't know on 3-4 Gen. vans, but on 5 Gen. vans, a broken flexplate doesn't give you a code or any symptoms other than a loud knocking sound.

If crank sensor get it's reading out of the flexplate, then yes, you may get those symptoms.
 

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02Caravan, thanks for posting photos, and I will never fuss "old thread".
Your photos look almost exactly like the flexplate in my 2002 3.8L van (4th gen, I'm here because also have a 3rd gen). I posted years ago It was cracked all around the bolt circle, plus radial cracks. It had rotated ~20 deg lagged yet still ran OK. I had heard a faint tinny sound when idling for >1 yr. Finally, I would hear a load clunk when starting to crank, but not always so must have depended on how the engine was clocked. Finally decided it must be the flex-plate. When I took it to the dealer, a few mechanics were hanging at the parts desk at the end of the day and said "bet that's a flex-plate" when they saw the flat box I was carrying.

For others diagnosing, I would start by spraying starter fluid in the inlet duct. If it idles fine on shots of that, you have a fuel issue. If not, put an inline spark tester on each plug and verify cylinder sparks (cheap at HF). If not, could be crank or cam sensor or coil-pack. I use a clamp-on timing light since faster. BTW, a cheap inspection camera is a USB "endoscope" ($15 ebay).
 

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If you have a bad crankshaft position sensor, camshaft position sensor, or flex plate, you will not receive spark OR fuel. The ignition coils and fuel pump are energized only after a valid crankshaft and camshaft position has been determined by the ECU.

ENGINE START-UP MODE
This is an OPEN LOOP mode. The following
actions occur when the starter motor is engaged.
If the PCM receives the camshaft position sensor
and crankshaft position sensor signals, it energizes
the ASD relay and fuel pump relay. These relays supply battery voltage to the fuel pump, fuel injectors,
ignition coil, and oxygen sensor heating element. If
the PCM does not receive the camshaft position sensor and crankshaft position sensor signals within
approximately one second, it de-energizes the ASD
relay and fuel pump relay.
The PCM energizes all injectors until it determines
crankshaft position from the camshaft position sensor and crankshaft position sensor signals. The PCM
determines crankshaft position within 1 engine revolution.
After determining crankshaft position, the PCM
begins energizing the injectors in sequence. The PCM
adjusts injector pulse width and controls injector synchronization by turning the individual ground paths
to the injectors On and Off.
 

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I also had a broken flex plate. See my thread:


Pics of my broken flex plate:



 

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02Caravan, thanks for posting photos, and I will never fuss "old thread".
Nothing wrong with posting on an old thread.

But, being lazy and not reading it (especially a short thread like this one) before answering is not acceptable, especially if you are providing a wrong opinion:

I say flex plate. Can be examined through the CPS hole with a video inspection cam.
O.P. had already found the problem (six months earlier) and clearly posted what the problem was:

I found the problem and I especially want to thank Special Edy, not only for the great information provided but also for the advise to not trust auto part store parts.

I was warned in another thread not to trust parts from auto parts stores. I will echo that warning.

When I first encountered the stall, no start situation I bought a new crankshaft sensor. Van still would not start......

Put the new sensor into the engine. Cranked the engine twice and it fired right up and is running great.
 
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