Having timing issues with my 3.9L and am getting frustrated. I purchased the truck a year a go it has 120000 miles on it. The truck ran great for about 2 months and then it started stalling at a dead stop while in gear. I check the codes and was telling me I have coil issues. Replaced coil and with in 2 weeks the engine was throwing new codes. P1391 Intermittent loss of Camshaft or Crankshaft position.

This is what I did.
1. Replaced distributor cap, rotor, wires, plugs.
2. Replaced cam and crank sensors with aftermarket parts.
3. Checked all wiring at sensors and relays for resistance and correct voltages.
4. Checked fuel pressures and fuel set.
5. Checked injectors.
6. Sent computer away to be checked and reprogrammed for my model truck.
7. Replaced all sensors at throttle body.
8. Checked cylinder pressures 160-180 psi throughout engine.
9. Removed and cleaned throttle body.
10. Checked distributor play and it is at threshold (3/16"play).
11. Put timing light on it and can see it running between 14-16 degrees and erratically jumping to 20-22 degrees on the crank.
12. Put a camera down the flywheel side and could not see any cracks or movement on flywheel.
13. No noise from timing chain.

Engine starts and runs strong in all rpm's. P1391 code is present and will not go away. Engine back fires when running down the road at a steady speed 2200-2500 rpm but not at idle or in park at same rpm ranges or above.
I did not check timing chain play yet, but I do not think the chain or cam is the issue because engine runs strong and there is no loss of power. I believe the distributor gear or bushing is warn giving me issues.

Is there anyone that had the same issues and went through all steps to diagnoses the issue that can verify my findings before I pull the distributor and shaft?
Any help is greatly appreciated.

 

Need to know what year your truck is so this can be moved to the appropriate tech section.

 

Never mind. I saw your other post. Moving to the 1st gen Dakota section for you.

 

There is a 95 and 96 FSM in the FAQ section.
If you have a magnum motor the timing is done by the computer. You cannot set timing at all. Adjusting the distributor only affects when the injectors fire in the cycle. If you had low idle it may be Throttle Valve cable adjustment. https://www.justanswer.com/dodge/1ot...-throttle.html
Setting of the fuel injector synchronization calls for a code reader with real time readings. There is a manual method.
http://www.bionicdodge.com/Download/...uel%20Sync.pdf

 

3/16" play in distributor bushings is quite a bit. I've never seen one that bad.is this "up and down" or "side to side" play? Did you take distributor out?
The timing light check does you no good. You don't "set timing" the way you would on an older engine. you need a scanner to do the job on your engine. they call it "set sync" within the scanner.
"put a camera down flywheel side" where? Did you pull starter? or thru crank sensor hole? that won't tell whole story about possible cracked flexplate, but that isn't all that common on these trucks anyway.
the 3.9 even though only 6 cylinders goes thru timing chains more often than V8s do. because they are an "odd fire" engine. just because it isn't making noise, it could well be stretched and valve timing could be off from factory new..... but lets not go down that path yet. with thos ecompression numbers if it is off, probably not by enough to worry right now... if you jump time there will be other indicators which you don't mention.

My 1st questions would be what brands of aftermarket crank sensor and distributor pickup did you use? What brands of tuneup parts did you use? Some aren't very good quality. I hope you didn't use something like "E3" spark plugs. plain old copper Champion or Autolite plugs work best in these. Are you SURE that you didn't cross any plug wires? There are bulletins about how you route plug wires on these engines that pertains to what you are complaining about. also bulletins about the oil pump drive bushing (under the distributor, that gear you see would have to come out to get to, its doable in the truck) causing misfires and bucking, chugging.
what you say you have done, raises more questions than answers, in trying to figure out what's going on. ,

 

Thank you all for the replies. To answer volaredon's questions I did not take out distributor yet but there is play in the distributor rotor when you rotate it. I grab the rotor and can spin it clockwise/counterclockwise to move it 3/16" No play up or down or side to side. I know very well that you can not set timing on this motor but you can still check it with a light. You can see it jump timing as it runs but corrects itself right away. Like I mentioned the motor runs strong. You stomp on it it opens up and runs. Skips timing at idle and pops at mid range while driving. I use BWD replacement parts for sensors and wires with copper Autolite plugs and no crossed wires. Put a camera down both sides of flywheel and did not see signs of cracks or movement. It is a cast steel flywheel not stamp steel. Also check flywheel position at top dead and it lines up with the sensor.

I am looking for a garage I can trust to set the injectors vs buying the bi-directional scan tool. Per onemore94dak instructions. I will update this post after completing fuel set.

 

The distributor has zero to do with timing; if it's jumping, I'd bet the crank position sensor is having fits.

And if it's BWD, several others have reported problems with them.

Try a Mopar sensor there and see if the spark settles down good.

RwP

 

Replaced Crank sensor with Mopar original. I have a new issue now. Runs like **** below 1500 rpm and smell rich. After it hits operating temp it runs and idles like it should.

 

I have determined what appears to have been the issue.
-I installed Mopar crank sensor and truck would not idle until warm.
-I tested all voltages and triggers voltages for the third time to and from the computer. All checked out.
-Positioned motor at TDC on #1 using crank balance wheel.
-Removed the distributor for inspection.
-Found that bolt was not extremely tight. Was snugged down but not tight. Someone removed or replaced the distributor prior to my ownership.
-Distributor looks brand new and had zero play or defects.
-Inspected cam gear and distributor gear inside the engine.
-Inserted a flat screw driver into distributor gear to make sure there was no extreme play in gear. (All check out)
-Question my self. (Why was there play in the distributor but not in the gear?
-Measured tab on distributor to make sure it was not warn. All kosher.
-Revisited cam gear. This time I noticed hard carbon build up inside where the distributor shaft mates.
-I chipped it away and cleaned out as much of it as I could with a rag and screw driver.
-Reinstalled distributor. Had to do this three times, each time cleaning out mating surfaces.
-Distributor dropped in the third time and I notice right away there was no play at all in distributor.
-Re assembled everything and truck started and ran as it should. I still have to road test it but I do not see any symptoms or codes anymore.
Conclusion: Gremlins I mean owner prior to me had not set the new distributor in properly causing a timing issue.
Two piece distributors are preposterous.

 

Glad you were able to work that out. That is also some new knowledge about the slot in the cam AFAIK. Thanks for coming back to let us know.