I found this "how to" on he interweb for a 93 model 3.9 Magnum V6, it should be the same I would imagine for the 1996?

here ya go:

The 93 models had no cheater methods, no scan tool apps to make life easier, so they had to be set manually. You'll need tools to rotate the engine by hand, remove the distributor cap (Philipps), loosen the distributor hold down and then (maybe) some chalk to mark the harmonic balancer if the marks are difficult to find. The distributor uses a 13mm hex bolt as its hold down fastener and is a bit tough to get to without a special distributor wrench, but you'll probably figure it out... =/

Start by removing the distributor cap. Take the left (driver's) side plug wires out of the cap completely to allow you to roll the cap off to the side, leaving three wires and the coil wire intact for future reference. You'll be removing #1, 3 and 5 plug wires and the firing order is (clockwise) 1-6-5-4-3-2.

Examine the rotor for excessive forward and back end play at the distributor shaft. If you can rotate the shaft enough that the swept space of the rotor tip exceeds 1/4", you've almost certainly got some damage to the distributor drive gear and block bushing, something that was uber-common on the 92 and 93 3.9 engines. Chrysler technical service bulletin 18-08-03 describes the procedure for removing and replacing the drive gear and block bushing as well as a rough adjustment process afterward. Let me know if you find enough shaft slop to merit an immediate repair.

Head to the harmonic balancer now and locate the V6 mark, which will appear to have been scribed with a scalpel... very light and hard to read. There will also be a V8 mark just for confusion-sake and looks very similar to the one you really need.

The V8 mark is located very close to one of the major scribe cuts in the balancer and is near TDC for cylinder #1. The V6 mark is flying off in space a bit, something like 132 degrees ATC. Mark it once found.

Rotate the engine until the distributor rotor tip is nearing the #1 spark plug location on the cap, then align your V6 mark with the stationary TDC mark on the timing cover (the old ignition timing mark).

It's important that you not back up if the mark is passed, as this would transfer some of the inevitable timing chain slack to the drive side of the camshaft. If another shot at adjustment is needed, back the engine up 20 degrees or more and then repeat the clockwise turning adjustment, stopping right at TDC.

With the distributor lightly loosened now, rotate it clockwise as far as the hold-down will allow. You can put the cap and wires back on at this point.

Turn the key on, being careful to not engage the starter.

Rotate the distributor counter-clockwise now until you hear a *click* from the relay bank in the underhood fuse block. If you're working from the driver's side of the truck, this will be easier to hear as it's right below you at this point.

The *click* happens as the cam sensor changes voltage states and creates a signal recognized by the PCM (engine controller). You could also backprobe the tan/ yellow wire on the engine harness side connector to monitor voltage if you're not comfortable with the *click* method. You'll be watching for a voltage transition from 0-5v or 5 to 0v... it's the transition point that we're counting as a cam signal. With the crank positioned at the V6 mark and the cam signal tripped... this is your sync adjustment. Lock it down.

If you'd like to repeat this part of the process, roll the distributor far to the CW position and start over. This keeps the rotational relationship between your distributor body and trigger wheel the same as if the engine was turning on its own.

You get but one *click* per key cycle, so the key has to be turned off and back on at each adjustment attempt.

If your distributor rotor looseness is excessive, repairs should be done, but you can temporarily get things running OK again by performing this procedure to compensate for wear and tear and the inevitable retarding of cam signal.

That's it!

 

That's it, wholly molly! Well mine is a 96, but I assume you would not have posted if it didn't apply. Since it runs really good for an engine with 186K on it, I'm going to assume the timing is ok, that is until it fails to pass the smog test again. Thank you for providing this info. But I really hope I dont need it. I'm out of town this week but will be back early next week to tackle this issue again. My guess (fingers crossed tightly) that the missing thermostat kept the engine from coming up to temp and that's why the NO was excessive.

 

Well... not to pee in your wheaties or anything, but typically cold running motors run excessively rich instead of lean.
NOx levels increase when the combustion temps go up, which does not have a direct correlation to coolant temp.
Retarding the ignition timing typically is what helps to lower combustion temps.

 

I read a very compelling post taking about how our engines run lean until brought up to operating temp. A lean condition of course means a lower ratio of fuel to air. Fuel cools the combustion chamber, so maybe, just maybe, I've already fixed it. I agree with your assessment but on the off chance that it may be ok already, I'm going to throw the dice and have it checked again. And thanks for not peeing in my Wheaties, that cracked me up! I'll post back the results. It may not be broke so I may not need to fix it. Wish I could check the NO level myself.

 

Yep another check will be needed. If you were in my neck of the woods. I'd recommend a smog shop near me where the owner will let me pre-test to my hearts delight in order to get that coveted "pass" mark. I have a '82 F150 with a 351 and that beast fought me long and hard on getting it to lower it's NOx. It finally took a carburetor jet change and backing a few degrees of timing out to get the old workhorse to run clean. He saw me about 5 times before it passed and just charged me for 1 retest

 

PCM uses crank sensor for ignition timing, there is a cam position sensor under the distributor cap that PCM uses to control injector timing. The relationship between cam and crank sensor is called Fuel Sync, and does indeed need to be set properly if the distributor is changed/moved. There is a procedure for setting the 'base' in the service manual. But, to get it 'right', you need a scanner that can read fuel sync. The 20 dollar parts store fellers aren't going to have a clue.

 

https://dodgeforum.com/forum/1st-gen...fuel-sync.html
http://www.bionicdodge.com/Download/...uel%20Sync.pdf

 

She Passed the Smog Test Today!!
Re-cap:
Failed Smog test due to High Nox
High Nox is caused by high combustion chamber temps
Replaced Catalytic Converter (thought it would convert the Nox to something else - guess not)
Replaced O2 Sensors - got a check engine light after the Cat was replaced - upstream O2 sensor
Filled to 1/4 full with premium gas - (see below)
Tested again and failed smog due to high NOx
Noticed that engine never got up to temp - found there was no thermostat - installed a 195. I read that the engine will run lean by default until coming up to operating temperature, then sensors have more impact, fuel richer. Lean fuel = high combustion chamber temps. Fuel cools combustion chambers, more fuel = cooler combustion.
Changed spark plugs, but old ones looked good
Put in a new PCV but old one seemed to work same as new one.
Ran Sea Foam in Gas, and through vacuum line, and added to oil - high compression adds to high temp in combustion chamber, getting rid of carbon might lower compression (long shot)
Flushed cooling system, added new coolant - (radiator had crud in it, would even drain)
Drained Oil with Sea Foam after 100 miles, added fresh oil and filter
Ran 1/2 tank of gas with Sea Foam, refilled to 1/4 full with Premium to discourage pre-detonation. Pre-detonation causes high combustion chamber temps (but I tried that before and it didn't help - figured it couldn't hurt.

I don't really know what solved the high Nox issue, but the levels were less than 1/2 of what they were before doing this lasted round repairs and troubleshooting.
My hunch is that the missing thermostat was the problem. I don't like doing the shot gun approach, replacing and trying everything at once, but time was a factor and I only got one free smog test. Can't knock success.

Thanks guys for your suggestions. If it hadn't passed today, I probably would have taken it to a mechanic that could retard the timing. Since as far as I knew, the timing had never been adjusted, I opted to not have it adjusted until after the smog test. Since she passed, no timing adjustment will be made.

All this was done so that we can get a replacement for the lost/misplaced Certificate of Title so that we can sell the truck.
All told, we are north of $800 in parts, ouch. I know we won't recoup that expense, but with all this new stuff, it should help sell the truck.

I hope this helps someone else some day - to that future person - figure what is causing the combustion chamber to be over 2500 degrees and you'll solve your high Nox problem.

Thanks again everyone!!!
Paul

 

You cannot adjust the timing on these trucks. It is set by the computer. Notice the links I posted above show that turning the distributor sets when the injector fires during the cycle. That is called setting fuel synchronization. I'd say your thermostat and flushing the cooling system helped.

 

I see, so can't adjust when it fires but can adjust when the fuel injects. I get it, thanks.

Now I notice that the dashboard is falling apart. Aways something.