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Discussion Starter #1
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.
 

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If the cam and crank are out of sync your spark and injector pulses would be affected.
It hard enough for the PCM to make a spark on time even harder to get an injector pulse, You have both.IMO you don't have a mechanical issue (Flexplate/timing chain).

I'm thinking a wiring issue or a PCM.
As for checking the flexplate, yes you need to remove the trans and remove the 8 bolts holding it to the crank to see if it cracked at the hub.
 

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There is a dust cover for the torque converter, removing it would give you access to the lower half of the flexplate and torque converter, then you can inspect it for cracks or damage.

Fuel Pressure is low at 42 PSI, it should be 55psi for the 3.3L, and 49psi for the other engines. You need to short the terminals of the fuel pump relay to get a proper reading









Some other useful information on the Crankshaft/Camshaft position sensors-















IGNITION SWITCH ON (ZERO RPM) MODE
When the multi-port fuel injection system is activated by the ignition switch, the following actions
occur:
• The PCM determines atmospheric air pressure
from the MAP sensor input to determine basic fuel
strategy.
• The PCM monitors the coolant temperature sensor and throttle position sensor input. The PCM modifies fuel strategy based on this input.
When the key is in the ON position and the engine
is not running (zero rpm), the Automatic Shutdown
(ASD) relay and fuel pump relay are not energized.
Therefore battery voltage is not supplied to the fuel
pump, ignition coil, fuel injectors or oxygen sensor
heating element.

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.

When the engine idles within 664 RPM of its target RPM, the PCM compares current MAP sensor
value with the atmospheric pressure value received
during the Ignition Switch On (zero RPM) mode. If
the PCM does not detect a minimum difference
between the two values, it sets a MAP diagnostic
trouble code into memory.
Once the ASD and fuel pump relays have been
energized, the PCM:
• Determines injector pulse width based on engine
coolant temperature, MAP and the number of engine
revolutions since cranking was initiated.
• Monitors the engine coolant temperature sensor,
camshaft position sensor, crankshaft position sensor,
MAP sensor, and throttle position sensor to determine correct ignition timing.
All images and quotes obtained from the Chrysler Voyager 1998 Factory Service Manual
 

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Discussion Starter #4
Special Edy, thanks a million. That is a ton of very useful information you provided, especially the steps for P1391.

I was wondering about the fuel psi and thought the psi might be a little low but was not successful in finding what it needed to be. Thanks for giving that.

I may have a couple of issues going on with low pressure and then the backfires on top of that.

When you say "short the terminals of the fuel pump relay", please explain what you mean by that - how do you do it without blowing something up?

Thanks
 

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The Fuel Pump Relay is the second relay down on the right side of my fusebox. If you stick a jumperwire between Terminal 30 and Terminal 87 of the socket, it will power on the device. Terminal 30 is connected to the battery, Terminal 87 is the fuel pump. Terminal 85 is Ground for the relay coil, Terminal 86 is switched power to the coil.
When 12V goes to 86, and 85 is grounded, power flows through the relay coil and it closes a switch between 30 and 87, which supplies power to the device. I've jumped the starter relay with a paperclip before, so don't overthink it.

You can do this for a few minutes without damaging the fuel pump. It's necessary since the fuel pump is inactive until the PCM receives valid signals from the Crankshaft and Camshaft position sensors, which means the fuel pump is only ever on while the engine is running. You're probably going to get a different reading while the engine is on and injectors are firing than when the engine is off.

I would lean towards the P1391 code though, it would be quite a coincidence to have that code be false and fuel pump issues at the same time. Suspect replacement parts, they NEVER, EVER last as long as factory parts, even if they are newer. If the Camshaft and Crankshaft Position Sensors have a warranty, exchange them; the diagnostic code should be proof enough to the parts store that they are defective. Otherwise, you could pull some for really cheap at the junkyard and I would trust those more than the Chinese ones from the auto parts store. Another option is to measure the resistance of the camshaft/crankshaft sensors across their terminals, and then measure a new one at the parts store. Don't forget that the camshaft position sensor is "very sensitive to adjustment", the distance it is from the camshaft sprocket can cause misreadings.

The Coil Pack could cause the same issues your having, intermittent failure even if you see sparks while testing. But once again the P1391 supersedes that suspicion.

You can check the timing of the engine by removing the front valve cover and a spark plug. It doesn't matter which cylinder; 2, 4, and 6 are on the front but any will work. There are two top dead centers for each cylinder, since the crankshaft rotates twice for every single camshaft rotation. One is between the compression and combustion strokes, and the valves are closed for roughly 180 degrees of crank rotation, 90 degrees for camshaft, before and after this TDC. This is normally the TDC you want for a timing light because it's when spark occurs. The other TDC is the one you want for my test, when the cylinder is between the EXHAUST and INTAKE stroke. You can see when the piston is at TDC by looking into the cylinder through the removed spark plug hole, or by sticking a screwdriver into the spark plug hole and feeling when the piston tops out.
When the cylinder is at TDC between EXHAUST and INTAKE stroke, both valves will be slightly open. The intake valve opens 2 degrees before TDC(almost imperceptible), the exhaust valve closes 12 degrees after TDC, with 14 degrees of overlap. This is degrees of rotation on the Crankshaft. The engine spins clockwise if looking at it from the front(or passengerside), so rotating counterclockwise from TDC will be before TDC, and rotating clockwise from TDC will be after TDC. There are 19 teeth on the crankshaft timing wheel, divide this from 360 degrees and the result is that the valve timing will be off by 19 degrees if the timing chain has skipped a tooth.
 

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Discussion Starter #6
Special Edy, thank you so much - great information. I would think a lot of people, not on me, will greatly benefit from your generosity. Little cold here today, but since I am not even a novice mechanic, I can take today to attempt and understand all of the information.

Reading about jumping the fuel pump relay. Am I correct in understanding that jumping between 30 and 86 will turn the fuel pump on, keeping continuous pressure at the rail, pressure which would not be continuous by just turning the key on - which is only a few seconds? During this time, a fuel pressure reading should be taken to get a more accurate pressure reading, one more accurate than what it would be by just turning on the key? You said it would be quite a coincident to have a fuel pump problem and a P1391 at the same time. However, if I do only get something like 42psi, in your opinion I would have a fuel problem?

I would reason that if I only have 42psi or so, I should check the fuel filter (changed a couple of years ago), perhaps check that the pump is getting 12V, and if all is ok, I should look at replacing the fuel pump?

Now, let me see if I have your timing comments down correctly - going clockwise.

I follow the 2° before TDC and the 12° after, making 14° (nearly a tooth - 19°) but I'm not sure where to "see" this movement. Do I look at the movement of the rocker arm down and up and say that is 14°? I think that I would have to turn the crankshaft nearly a 1/2 turn to get one complete TDC stroke, the TDC being just about 1/4 turn of the crankshaft. (?)

Do the rocker arms do nothing during the compression stroke and therefore the valves are closed to allow compression and combustion? If that is the case, if the piston is at TDC and the rocker arm doesn't move, that would be the compression stroke. (?)

Thanks for you patience and time. I really appreciate the help and information.
 

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A 3.3L will start and run with 42 PSI. I remember something about the manual being wrong about the actual pressure spec and guys chasing their tails back in the day.
If I get a chance I can check the fuel pressure of my 94 I just drove today.

If the flexplate is cracked at the hub you would be able to see it thru the inspection cover, if you're lucky you might see some metal filings.
Checking the valve timing is going to a chore without any timing scale on the balancer.
 

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Discussion Starter #8
Thank you 1995 Sport. I would appreciate you giving me your fuel psi.

I agree with the timing. It seems they could have provided some easier way of verifying the timing.
 

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Discussion Starter #9 (Edited)
Still have the overall problem but did accomplish the elimination of a couple of possible causes.

Fuel Pressure: did some research on fuel pressure regulator. Auto Zone, Advance Auto and O'Reilleys all have the regulator for around $89. You can buy a new fuel pump which comes with the regulator for around $110. Got a loaner fuel pressure gauge set from Auto Zone ($160 collateral refunded on return), Advance said they did not loan them. Hooked the gauge to the fuel rail, turned the key on. 44psi after cycling the key on/off a number of times. Left gauge attached to the rail. Removed the fuel pump relay from the power distribution center (the fuse box), drivers side under the hood. I removed the negative battery cable just to be on the safe side. Straighten, bent and jumped terminals 30 and 86 of the removed relay. The relay has five blades. Three all run the same way. There are two that run the same way. The jump needs to be done between the slots where the two that run the same way plug into the fuse board. Once the paperclip was in place, I reconnected the negative cable. You will hear the fuel pump kick on and run. I glanced at the fuel gauge and the psi was at 49psi. I removed the paperclip. Replaced the fuel relay.

In doing the research on the fuel pressure regulator and fuel pumps, all pumps sold by the parts stores mentioned above stated in the specs that the fuel pressure regulator was a 49psi regulator. Special Edy pointed out that the 3.3L should be 55psi. Since I can't seem to buy one with a 55psi regulator, I guess I'll try to live with the 49psi.

Flex Plate: I inspected the flex plate through the "flywheel dust plate"/"flywheel inspection plate". It really wasn't that hard to do. I raised both front wheels and used jack and jack stand on each side. Removed negative battery cable - be sure to do this. Removed right front wheel. Removed access cover from splash shield - opposite crankshaft end. This access hole will give you access to the bolt on the end of the crankshaft. Use this bolt to turn the crankshaft to make the flywheel rotate so you can examine the flywheel. To locate the plate, slide under the engine head first and slide back past the oil pan. If the part of the oil pan which is the lowest part is directly above your face, if you turn your head left to about the 10 o'clock position you will notice a rather flat, up and down vertically, cover/plate. There is one 10mm bolt in the very bottom of the plate. The plate has one more bolt which is to the front of the vehicle and higher up than the obvious 10mm bolt. Remove both of those 10mm bolts. You won't be able to do anything with the plate at this point.

There is a (as I recall 18mm) bolt to the top left of the plate which goes through a transmission mounting bracket, then through the plate and then into the transmission housing. You will have to remove this bolt, but you can't gain access to it until the brace which runs from directly in front of the bolt up and to the right. There is one bolt on each end of this brace. I removed this brace entirely for safety purposes - I didn't want it dangling down. Once the brace is removed, remove the 18mm bolt which secures the bracket and the inspection plate. Once this bolt is removed, swing the inspection plate from the front of the vehicle toward the back - don't pull it out from under the transmission bracket. If you leave it in place, just swing it out of the way, once you inspect the flywheel/flex plate all you have to do is swing it back into it's original position and bolt it back down.

Once the inspection plate was out of the way, I could see what amounted to about 20% of the flywheel. I put a black felt marker mark on the flywheel so I would know when I made an entire revolution of the flywheel. Using a flash light, I inspected the part of the flywheel I initially could see, didn't see anything, and slowly rotated the crankshaft, inspected the flywheel, rotated again, inspected again, repeating until the black mark was once again visible. I found nothing whatsoever wrong with the flywheel and no cracks or anything toward the center of the flex part of the flywheel.

Reverse the procedure to reinstall the inspection plate.

I am quite confident the flex plate is not my problem.

I have got to find some way to verify the timing. That is my next move.
 

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Special Edy, thank you so much - great information. I would think a lot of people, not on me, will greatly benefit from your generosity. Little cold here today, but since I am not even a novice mechanic, I can take today to attempt and understand all of the information.

Reading about jumping the fuel pump relay. Am I correct in understanding that jumping between 30 and 86 will turn the fuel pump on, keeping continuous pressure at the rail, pressure which would not be continuous by just turning the key on - which is only a few seconds? During this time, a fuel pressure reading should be taken to get a more accurate pressure reading, one more accurate than what it would be by just turning on the key? You said it would be quite a coincident to have a fuel pump problem and a P1391 at the same time. However, if I do only get something like 42psi, in your opinion I would have a fuel problem?

I would reason that if I only have 42psi or so, I should check the fuel filter (changed a couple of years ago), perhaps check that the pump is getting 12V, and if all is ok, I should look at replacing the fuel pump?

Now, let me see if I have your timing comments down correctly - going clockwise.

I follow the 2° before TDC and the 12° after, making 14° (nearly a tooth - 19°) but I'm not sure where to "see" this movement. Do I look at the movement of the rocker arm down and up and say that is 14°? I think that I would have to turn the crankshaft nearly a 1/2 turn to get one complete TDC stroke, the TDC being just about 1/4 turn of the crankshaft. (?)

Do the rocker arms do nothing during the compression stroke and therefore the valves are closed to allow compression and combustion? If that is the case, if the piston is at TDC and the rocker arm doesn't move, that would be the compression stroke. (?)

Thanks for you patience and time. I really appreciate the help and information.
Okay, so everytime you rotate the crankshaft 360 degrees, all the way around, the pistons are going to rise and fall exactly 1 cycle, the camshaft will only turn 1/2 of a rotation for every 1 rotation of the Crankshaft. If the cylinder is at TDC, the piston is at the very top of its stroke, fractions of an inch from the sparkplug.
TDC is theoretically when the piston is perfectly as high as it would go within the cylinder, like 0.00000(insert many zeros)000001 degrees, but in practice it only needs to be within a few degrees since the smallest amount our engine can be off is by a massive 19 degrees.
Starting at TDC, if you rotate the crankshaft 180 degrees, 1/2 a turn, the piston is now at BDC, bottom dead center, the bottom of its stroke.
Starting at TDC, if you rotate the crankshaft 360 degrees, 1 full turn, the piston is now at TDC again.
Since the camshaft rotates half as fast as the crankshaft, the piston goes through 4 strokes, 2 up and 2 down, for every camshaft rotation or cycle of the engine. Hence it is a four-stroke engine.

On the Intake stroke, the intake valve is open and the piston moves down from the TDC to the bottom of its stroke. The piston moving down sucks air and fuel into the cylinder like lungs expanding.
On the Compression stroke, the intake valve closes and the piston moves up from the bottom of the stroke to TDC, compressing the air and fuel inside to roughly ten times its normal pressure.
On the Combustion stroke, the sparkplug ignites the compressed air/fuel mixture. The resulting explosion pushes the piston down from TDC to the bottom of its stroke.
On the Exhaust stroke, the exhaust valve opens. As the piston goes from the bottom of its stroke to TDC, it pushes all the exhaust gases out the open exhaust valve.

In order for the engine to run more efficiently, the valves open and the sparkplug fires a little early for their respective strokes. This is because an engine running 600-6000rpm is performing 12-120 strokes per second and there is delay for the explosion to travel or air to begin moving in and out of the cylinder. This is also known as timing advance.



To determine TDC for a given cylinder, you are going to remove the spark plug and look inside the cylinder or feel inside with a screwdriver. You should be able to do this on Cylinder 2, 4, or 6 on the front of the vehicle, it doesn't matter which one you choose. Just find when the piston stops moving up, you should be able to get TDC for that cylinder within a few degrees of error. Its will start moving very slowly once its close to TDC, exponentially slower, which makes it hard to nail exactly. With the valve cover off, rotate the crankshaft backwards and forwards a few degrees. If the cylinder is at TDC for the compression/combustion stroke, neither of the rocker arms or valves will move. That's the wrong TDC. On the intake/exhaust stroke TDC, both valves should be just barely open. The intake valve will close completely if you rotate the Crankshaft 2 degrees counterclockwise(BTDC), and the exhaust will fully close if you rotate the crankshaft 12 degrees clockwise(ATDC).

You're looking for the movement of the rocker arm and valve. I'm not sure if there is any valve lash(slack between the rocker arm and valve stem) when the valve is closed, because we have hydraulic lifters that are supposed to pump up with oil and remove valve lash. But you may be able to wiggle the rocker arm slightly when it isn't pushing down on the valve, aka when the valve is closed. The rocker arm will probably noticeably tighten up to your fingers wiggling it when it starts to open the valve, but you should be able to see some noticeable movement anyways.

If your timing is off one tooth retarded- the intake will begin to open at 17 degrees ATDC(Clockwise) and the exhaust will close completely at 31 degrees ATDC(Clockwise).
If your timing is off one tooth advanced- the intake will begin to open at 21 degrees BTDC(Counterclockwise) and the exhaust will close completely at 7 degrees BTDC(Counterclockwise).
 

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You cannot actually SEE where these flexplates crack until you REMOVE the flex plate, as the cracked circle will be under a retaining washer/ring.
 

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You cannot actually SEE where these flexplates crack until you REMOVE the flex plate, as the cracked circle will be under a retaining washer/ring.
I would actually suggest donning on a pair of safety glasses, climbing under the engine compartment, and watching the flexplate while a helper cranks the starter over. There would be a noticeable wobble if its cracked. I dont know what the clearance is on the Crankshaft Position Sensor is, but the Camshaft Position Sensor is supposed to be mounted the thickness of a sheet of paper away from the cam gear. Any noticable wobble on the flexplate would potentially throw the sensor off.

Im still putting my money on a faulty Cam/Crank sensor. They were both replaced, "OEM" replacement parts that don't fail prematurely on a 20 year old vehicle are unicorns made of unobtainium.
 

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My 2006 with 300,000 miles had similar problem. It turned out to be the fuel rail harness. It was completed fried. It located under the intake manifold and is easy to change.
 

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Discussion Starter #14
Thanks to Speedy Edy for the clarification on the timing procedure.

Checked the timing this afternoon - and that is not my problem either.

The procedure is rather straight forward. Disconnected the negative battery cable. Took #2 sparkplug out. Disconnected the air breather tube from the valve cover. Took all 10mm bolts out of the cover. There are two bolts behind the cover which are a little tricky to get out and back in but overall not that big a deal. Had to remove the two 13mm bolts holding the front fuel rail down - did not attempt to pull the injectors out of the engine - just needed enough room to rock the cover away from the engine.

Raised both sides of the van and put on jack stands. Removed front right passenger side tire. Remove the crankshaft access cover from the splash shield. (Used 5/8 inch socket to turn the crankshaft.)

Placed a plastic straw into the spark plug hole, it went well into the engine indicating the cylinder was near the bottom. Slowly turned the crankshaft and the straw slowly rose out of the spark plug hole.

I followed the observation procedure outlined by Speedy Edy above. Hard to do with just one person, so I got the wife involved to observe the rocker arms and the straw.

As as result, I don't think the timing is off even a tooth - I think it is dead on.

So, everything has been checked out and the engine still will not start and run as it should. The things that appear to check out ok:

Both the cam and crank sensors fluctuate between .5v and 5 v as the crank shaft is rotated. This indicates both are ok.

The injector wires were checked with a noid light and it indicates they are ok.

Fuel pressure is 49psi, which should work.

The flex plate looked ok.

The timing is ok.

The throttle position sensor is at .5 v at closed throttle and goes up to just about 5v at wide open. Indicates the TPS is ok.

I cleaned both the MAP and the IACM but cannot verify they are both working.

I have not checked the injectors to see if they are firing - but, this problem started with the engine just cutting off and not restarting. I don't think all injectors went bad at once.

There is fire at all cylinders.

I went back and took the #2 plug out and wedged a rolled up paper towel in the hole. I cranked the engine 5 or 6 seconds and checked the paper. There didn't appear to be any gas on the paper. If I am right, that would indicate a fuel issue. Should I be able to detect gas on the paper with cranking the engine 5 or 6 seconds. If I have fuel at the rail at 49psi (Speedy Edy said 3.3L should be 55psi) but not in the cylinders, I go to injectors not working, TPS, MAP and IACM.

Any suggestions would be appreciated.
 

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Discussion Starter #15
Thanks Road Ripper for the comment. I was somewhat aware of that but as opposed to pulling the trans "to see", I was rather surprised how much of the flywheel you could actually see. If, and I know it is totally possible, the flex plate is cracked only under the retaining ring, it would have to be a very precise and very clean break. There isn't much on the net about the flex plate but all pictures of bad plates which I have been able to find, if I had anywhere near the same damage I would have been able to see.
 

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Discussion Starter #16
Thanks choctawman, I am kinda back in that neighborhood. I checked the harness with noid lights and got good readings but as it has turned out I think I do have a fuel problem.
 

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Discussion Starter #17
Special Edy, let me first of all apologize for referring to you as "Speedy Edy" a couple of times in my posts. That is an excellent suggestion. If you see my last post about not having gas on a paper towel, I am going to look at the fuel issue one more time and if that isn't it, I'll look at the flex plate again. Thanks a lot for the suggestion.
 

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Thanks to Speedy Edy for the clarification on the timing procedure.

Checked the timing this afternoon - and that is not my problem either.

The procedure is rather straight forward. Disconnected the negative battery cable. Took #2 sparkplug out. Disconnected the air breather tube from the valve cover. Took all 10mm bolts out of the cover. There are two bolts behind the cover which are a little tricky to get out and back in but overall not that big a deal. Had to remove the two 13mm bolts holding the front fuel rail down - did not attempt to pull the injectors out of the engine - just needed enough room to rock the cover away from the engine.

Raised both sides of the van and put on jack stands. Removed front right passenger side tire. Remove the crankshaft access cover from the splash shield. (Used 5/8 inch socket to turn the crankshaft.)

Placed a plastic straw into the spark plug hole, it went well into the engine indicating the cylinder was near the bottom. Slowly turned the crankshaft and the straw slowly rose out of the spark plug hole.

I followed the observation procedure outlined by Speedy Edy above. Hard to do with just one person, so I got the wife involved to observe the rocker arms and the straw.

As as result, I don't think the timing is off even a tooth - I think it is dead on.

So, everything has been checked out and the engine still will not start and run as it should. The things that appear to check out ok:

Both the cam and crank sensors fluctuate between .5v and 5 v as the crank shaft is rotated. This indicates both are ok.

The injector wires were checked with a noid light and it indicates they are ok.

Fuel pressure is 49psi, which should work.

The flex plate looked ok.

The timing is ok.

The throttle position sensor is at .5 v at closed throttle and goes up to just about 5v at wide open. Indicates the TPS is ok.

I cleaned both the MAP and the IACM but cannot verify they are both working.

I have not checked the injectors to see if they are firing - but, this problem started with the engine just cutting off and not restarting. I don't think all injectors went bad at once.

There is fire at all cylinders.

I went back and took the #2 plug out and wedged a rolled up paper towel in the hole. I cranked the engine 5 or 6 seconds and checked the paper. There didn't appear to be any gas on the paper. If I am right, that would indicate a fuel issue. Should I be able to detect gas on the paper with cranking the engine 5 or 6 seconds. If I have fuel at the rail at 49psi (Speedy Edy said 3.3L should be 55psi) but not in the cylinders, I go to injectors not working, TPS, MAP and IACM.

Any suggestions would be appreciated.
The MAP, TPS, and IAC are irrelevant to engine startup. An electronically fuel injected engine always starts with the factory fuel map. Once it is running, it attempts to use feedback from the MAP, O2 sensors, Intake and Coolant Temperature, TPS, Speed Sensors, and whatever other data is available to improve performance and emissions. But to start, the ONLY sensors you typically need are the Crankshaft and Camshaft position sensors. You could probably disconnect every other sensor on the vehicle and it could still start and drive in limp mode down the road. The reason those two sensors are the highest priority is because they establish ignition timing and fuel injector timing, and the engine cannot function without ignition timing data.


I keep thinking of things that could be bad, but every time, I go back to the P1391 code and the fact that both the Crankshaft and Camshaft Position sensors were replaced recently.

In particular, the Camshaft Position sensor, Crankshaft Position Sensor, and Ignition Coil Pack are simply a winding of coils inside. They work through creating electric currents by using magnetic fields. All three often fail in such a way that they begin to work intermittently, and not at their full capacity. A failed coil pack will often produce visible sparks, but not at a high enough voltage to ignite the cylinder or reliably. I don't think you have a coil issue, since we have essentially three coils in a single package and two or three would need to fail to prevent the engine from running(a V6 would probably run on half its cylinders).

Without a proper Crank/Camshaft position signal, you wouldn't get gas on the paper towel because the injectors wont run.
 

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Discussion Starter #19
Choctawman, you said you had a similar problem. Would you be driving along, engine running fine, and it just cutoff?
 

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Discussion Starter #20
Thanks Special Edy. I totally appreciate your comment regarding the reliability of sensors on the market. I may have left it out but the coil is also a recently purchased coil so I don't think that is the problem. I bought the crankshaft sensor just before I bought the coil. I did not replace the camshaft sensor.

I am going to do as choctawman suggested and check out the entire injection wiring harness. If I find nothing there, I'll order a new camshaft sensor. If that fails, I'll do your suggestion and take a look at the flex plate as it turns.

Again, thanks for the help.
 
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