Canister above spare tire looked to be original and intact, with no physical damage, though I cant rule out internal damage/clogged evap lines just yet.
With the help of my son keeping it running, I was able to put a timing light on it. Engine was revved as stable as possible to between 1000-1500 rpm on the tach to keep it running. The distributor was advanced all the way, and my timing showed 20 degrees BTDC!
The hood label calls for 10 BTDC at idle.
As I understand it, engine timing advances as RPMs increase, SO with RPMs at the 1500-2000 range engine would have advanced timing to the 20 BTDC I measured with light.
This means at idle (800rpms), I would likely be 25-40 degrees retarded on the timing, with distributor advanced as far as it'll go!
This likely explains the lack of idle, occasional backfire through throttle body, etc.
I did ensure rotor pointing to #1 with crank/cam at TDC, spindles backwards "D" at the 11:30 and 4:30,but its still off.
Looks like the next step will be to pull oil pump and distributor, rotate drive spindle clockwise to advance, and check timing again.
It may be something else as well, but I'll need to correct this before checking anything else.
I'm reminded what a pain these engines are to time. Keep you posted.

Possible that this might be part of the problem? Look in the service manual located on this site,it explains the correct procedure for checking & setting timing. In the index go to - EC. Good Luck

Not the correct way - NOT SURE if this will work - Set the timing mark on TDC - Regardless where the rotor is pointed on the distributor, use this as number 1 position on the cap. Could also move the wires one position right or left on the cap? Might help to determine if this is part of the problem?

Could also try using a digital inductive timing light?

I've checked the canister and found no cracks or physical damage, though I'm not ruling out internal damage or clogged evap lines.
I discovered that my timing is retarded by at least 10 degrees, so I want to correct that first.
With my son keeping truck running, between 1500-2000 rpm, I put timing light on and found it was 20 BTDC. The sticker under hood calls for 10 degrees BTDC. As I understand it, timing advances with an increase in RPM, so if I was 10 degrees off at 2K RPM, then I am probably off even more at idle! The distributor is advanced all the way, so no way to tune it any more. Funny thing is I have crank and cam at TDC, and rotor lined up with #1 wire with spindle at 11:30/5:30 position.
I suppose the truck could care less what it's supposed to do, and insists I adjust to what it likes.
Back to removing oil pump and distributor, turning spindle clockwise a notch or two to advance, until I can get the timing in line.
It may be something additional, but I have to get timing right first. Will keep you posted.

I checked the canister and evap valve with no physical damage present. Whether its clogged or not is yet to be determined.
It's still holding and idle, and with my son keeping it running at 1000-1500 rpms, I put timing light on it, and found it to be at 20 degrees BTDC. The label on the hood specifies 10 degrees BTDC.
As I understand it, timing advances with RPM increase, so I'm likely running more than 10 degrees retarded on the timing!
Time to pull oil pump and distributor, reset one tooth at a time, and check.
If these symptoms persist after timing is in line, is there another likely culprit such as the TPS or Idle control valve that would cause these symptoms?
The only code I'm getting is P1320 primary ignition signal failure. I've replaced distributor and crankshaft position sensor. Small box next to #1 injector showing ok at 2.17 ohms.

Yes, I'll try that. #1 piston straight up. Rotor is pointing to #1 (11:30 and 5:30). Camshaft sprocket key almost straight up and down. Will let you know what I find.

Turns out I have a bad MAF. Disconnected it and truck started and revved much smoother, though still not holding idle. With the sensor disconnected, cat is now getting hot, glowing. While I await the arrival of new MAF, why would disconnecting MAF cause cat to glow?

Rather surprised that a code didn't appear. Might try testing all the sensors? Gets expensive doing the hit & miss. Ever get the engine running to a point where you can check vacuum? Also test both temp.sensors on the intake manifold.

Haven't checked vacuum yet as its still not holding an idle, though I'll see what it reads while feathering the gas.
Performed check on MAF and it was only getting 2 ohms at wide open throttle. I read I should be looking for 4+. The only code received was the P1320 ignition signal. Hopefully, the new Hitachi MAF will solve the no-idle issue as well as the cat heating up due to unburned fuel/ running rich. Can a faulty MAF cause a no-idle situation?
You're right on the two temp sensors, and I believe it'll be worth the $40 to go ahead and change both.
Some of the others can be expensive (TPS, IAC, etc) and I'd prefer to test before replacing.
Any tips on what other sensors to test and the procedure? A link you came across perhaps?

A couple good sources - The Nissan service manual - Easyautodiagnostics.com. Couple other things to check - check the plug located next to the positive battery. Look for corrosion & check for good continuity. Pull the (right) kick panel and ensure the ground wire has a good ground source. You're right the sensors are high buck. I purchased a cheap engine core from a salvage yard. Before testing sensors make sure the engine is at normal operating temp. Do the vacuum & compression test.

Been a little while since I could do more tests. I hooked up vacuum gauge today and its showing almost no vacuum. I have to keep foot on pedal to keep running, and vacuum gauge is almost zero. When I release the accelerator, it shows maybe 2 pounds. I haven't checked compression or fuel pressure yet, because it does rev smoothly. I've replaced all vacuum lines and hoses, but zero vacuum tells me perhaps a MAJOR leak somewhere.
Could ingnition timing being off cause this? Could a bad IACV also cause these symptoms?

Kind of wondering why I haven't seen any posts in awhile. Been watching social media thought I would see a guy chopping a 1997 Nissan pickup to pieces with an axe. The IACV along with other things could cause problems. The valve isn't cheap. Test the valve and make sure you have power at the plug. Check pcv valve & throttle body. Take a vise grip wrap the jaws with vinyl tape, assuming the truck has power brakes & pinch the hose going to the booster. You can also pinch off various vacuum hoses might be able to find the leak source. Definitely check compression put that on the high priority list of things to do list. Can't remember if you replaced the EGR valve? The valve if not functional could cause problems. Keep me posted if nothing else mine runs excellent could make a road trip and we could chop both of them to pieces. Body work is going good, would be going excellent back living the good single life.

Thanks, I have the compression test on the list. (replaced rings, bearings, EGR).
I did perform a vacuum check at the brake-booster hose going to the engine. Strange result was that it showed zero vacuum initially, but when I revved the motor, vacuum INCREASED to about 15 inches.
I next disconnected IACV/ FIC from the wiring harness, restarted, and no change in performance. FIC solenoid clicks when applying 12v, and piston spring look ok. Haven't pulled IACV quite yet.
Tried out the new OBD2 scanner (Autel AL519) to capture live data. Still keeps popping the P1320 code after 2nd replacement distributor and clearing codes.
Results of the live data below:


<a href="http://s921.photobucket.com/user/jonath ... 1.jpg.html" target="_blank"><img src="http://i921.photobucket.com/albums/ad53 ... Data_1.jpg" border="0" alt=" photo LiveData_1.jpg"/></a>

Good Recommendation on the scanner. As the data shows, fuel trim is within specs. Notice the increased RPMs I had to keep it at to run it.
With gas pedal held steady, tach lopes between 1000 and 1500 rpm. Pop-ing from intake, cat gets hot, and still has the P1320 code.
Anything you can determine from the data will be of great help!

To be honest Haven't used that scanner before. When you clamp off the vacuum source to the booster make sure you clap it off more toward the engine. There is a valve located between the engine and the booster. Thought the valve maybe malfunctioning.or the booster itself might be leaking. Doing the compression test will help. The fact the p1320 appeared again makes me question the integrity of the replacement distributor. Not a fan of aftermarket over the pond distributors. Cross match the truck vin number with the distributor number.

Happy new year, waited for it to warm up a bit here as I'm not a fan of extremes. 65 in Houston is as good as it gets in January.
Compression test with distributor midway showed 95-110 across cylinders.
Distributor retarded shows 95-100.
Distributor advanced shows 125-140 across. Advancing distributor increases compression. New rings, bearings, rod bolts. New NGK plugs fuel fouled, won't hold idle, and cat getting hot. Suspect slow ignition timing.
Retarded timing resulting in lower than normal compression readings?
Advance timing by pulling distributor and moving spindle clockwise a tooth at a time, then recheck compression.?

MINUS 23 below here last week in Minnesota. Heat wave this week above 30 degrees. Couple questions what's the dry compression - Number - 1-4 ? What cylinders have the 95 lbs.? Not unusual to get 95 lbs on a rebuilt. If the 95 lbs. are next to each other on the firing order, MIGHT ? Be dealing with a intake - cross fire or a vacuum issue? Not sure what the exact compression should be or ratio. Depends where the engine originated from. Could be over the pond? Hope the dry compression isn't - low of 95 lbs - high 140.lbs. When you did the rebuild did you replace the cam shaft? Could be dealing with the wrong cam shaft application? Bad cam shaft lobe or fuel injector issue could be the source. Still have the same engine code appearing. Happy New Year My goal for 2017 is to get your truck out and running hopefully long before 2018?

That's cold! Of course I avoid the 105 summer heat working on the cars. If you're down Houston way, I'll take care of the accommodations.
Dry, cold, open throttle compression:
1-122
2-133
3-133
4-140
Open throttle makes a difference!
Newly rebuilt head with cam fom Ramcyl.head in St.Louis.
New Hastings rings. New head gasket, chain, tensioner, dist.,plugs,wires, injectors, Egr, fuel pump, filter, and much more.
Plugs are fuel fouled, cat glows,revs great, but no idle.
Timing retarded? Fuel pressure regulator?
Idle control valve?
With all the new parts, work, this has me stumped.

The 122 makes me nervous. Should have told you to unplug the fuel pump relay. Even with the 122 it should still idle. Still displaying the same engine code? Did you replace the distributor if you did I hope not with one of those over the pond aftermarket disposable ones.

Yes, I pulled the fuse for the fuel pump, removed all spark plugs, then threaded in compression tester to each cylinder one at a time. Now, factors that could be causing the 122 are engine was tested cold, and I suspect timing may be off, although I've aligned timing (TDC, cam, distributor spindle at 11:30-5:30 with rotor pointing to #1).
Distributor has been replaced 3 times, I am using aftermarket, can't believe they would send me 2 bad ones. I reinstalled factory distributor, and same thing, FSM continuity test between plug-in and coil tower shows no continuity.
In addition to the idle, I'm getting code P1320 (coil/ distributor signal fault) and its dumping gas into the cat causing it to get hot. Of course I dont let it get to that point, and turn off after 20 seconds or so.
I'm suspecting idle control valve, fuel-pressure regulator, or a loose wire in the harness bundle.
I read a post on here that inside the harness, there are 4 wires that a just pigtailed together at the factory, and have a tendency to come loose (like after an impact?) causing all kinds of idle mayhem.

Would be nice if they were to fix this site so when you answer a post everything doesn't vanish before your finished Then they say a problem has occurred at the site WELL FIX IT !!! Fuel pump regulator could cause the cat issue. Could also have an injector sticking? Take a long screwdriver- with the engine running place the tip against each injector should be able to place your ear against the screwdriver head and hear a continuous clicking sound. Check the plug at the positive battery cable located on top of the battery. Test for continuity & corrosion.

If you want PM me and I will send you the distributor taken out of a running truck that ran perfect. Just let me know where to send it. We can work out the $$.$$ dollar amount at a later date.

PM sent. Injectors are all new, fuel pressure regulator is still original, so a possibility. Lets try the known good distributor as FSM points that direction.

PM sent..... Also there's a splice located on the driver side firewall. Poor factory workmanship. The splice is part of the harness that leads to the distributor. Make sure the connection is good. You might have to open the harness to gain access?

Another possibility the ECM located under the passenger seat is bad possible after the collision? Might be worth pulling the seat and checking for a good ground?

Shows good ground to the ecm. FSM is connector M111. Not sure if ecm itself is faulty though. Replaced fuel regulator, no change. Im leaning towards timing, I recall when I did chain years back I set it up to specs and didn't run right. Today I advanced distributor all the way and noticed improvement, and when I had it mid-range it wouldn't even start. I'll need to pull pump and advance a tooth.

Any possibility of setting the timing at TDC - remove the oil pump shaft - install the distributor in the correct position & install the oil pump shaft??

Of course, took care of it this morning. The symptoms remain: starts then lopes between 1500-2500 with gas pedal steady, then dies after a minute.
Idle control valve? I disconnected and no change in symptoms.
It is possible vacuum lines not reinstalled correctly because they were not tagged at teardown (lesson learned). I had reinstalled using FSM diagram. Recall, vac gauge showed 10psi of boost instead of vacuum when installed to brake booster hose.

You need 18 plus inches of vacuum in order for the engine to run decent. The booster & the pvc valve could result in poor idle. I think the engine should at least idle even if a few lines were not correct.

You are correct, and I'm getting nowhere near that, which is likely why its loping and running extremely rich (cats glowing). Have you ever had an idle control valve/ FICD fail to the point that a massive vacuum leak is causing symptoms similar to this?