Aloha all, my rebuild has turned into a troubleshooting fiasco and I wanted to make a specific thread for the issue. I'll try to be as clear and accurate as I can with my symptoms.

After resetting the KAM, engine starts and idles normally. In the process of trying to relearn idle it begins to surge and will not smoothly idle. I shut engine off after failing to reach steady idle.
Second start, engine surges worse and has trouble running. Code p0320 presents.

This has happened the same way three times so far.

I have confirmed that the crank sensor is functioning properly.
I have confirmed that the PCM is receiving the crank sensor signal.
The wiring between crank sensor and PCM is intact, including the shielding.

some confusing extra info:
On my second attempt to relearn idle, it made it 5 minutes at idle without any noticable issues or surging. I took it out for a drive and got it up to speed and also ran it at 2500 rpm for a minute with no noticeable issues. Brought it back, turned it off. Turned it back on, and surging is back as well as p0320.

 

Check coil pack 4 wire connector and firing order on coil pack, making sure spark plug wires are pushed down
3 4
2 6
1 5
front

Unplug CAM sensor and start engine, should get a Cam sensor code
Crank sensor is the Big Kahuna rpm sensor, but cam sensor is used as a comparison rpm sensor and misfire sensor

I would replace Crank sensor on spec, also make sure crank sensor is close enough to tone ring, if you have an old style timing light you can use the strode effect to see tone wheel distance to crank sensor with engine running
How does tone wheel look?
Nice and clean

 

Spark wires all check out, and when it does idle it is clean and smooth. I would classify the issue as intermittent verging on constant.

I'll try the unplugged cam sensor, thanks. I replaced the cam sensor during the rebuild, and then when this issue kicked up I swapped back in the old good sensor to see what happened, no change.

I am replacing the crank sensor, just waiting for it to get here. The balancer pulley is new. It's actually different than the one that was on the truck. Old one looked like this:



New one like this:


Ford assured me it was an updated part and backward compatible so to speak, but I have my doubts considering the current issues​​​​. I am curious if the new sensor will work better with the cheap cast tone ring they pressed on the pulley. Engineering progress.

I'll try to get a recording file of my PIDs while I try to start it tomorrow.

Is it possible the p0320 is a symptom of the rough idle or a mechanical/timing issue rather than an electrical issue?

I'm also gonna get a can of carb cleaner and check for intake leaks. If I had unmetered air while it was trying to learn idle would it present this way?

 

Yes, its a bit of "the chicken or the egg" for the code vs the rough running, not sure?

Create a vacuum leak and unplug IAC Valve, then see if higher idle(above 1,200rpm) is stable, or also wanders
Unplugged IAC takes computer compensation of changing idle RPMs off the table

If wandering is still there then fuel mix issue
If RPMs are stable then could be CKP signal was erratic, telling computer RPMs were falling when they weren't so it opened IAC a bit more, and then RPMs rise too far and computer has to close IAC, ect........ so wandering idle

Yes, I have seen both kinds of tone rings, not sure if it would be an issue, I certainly like the earlier version better, it "looks" like it would be better, lol
Then newer one "looks" thrown together

 

I'll try the forced vac leak, but if I unplug IAC as it is the engine dies quick.

The coil pack is old, and I reused my fuel injectors, so I'll check those out too just to rule them out.

The one symptom that's sticking out to me the most is how if I reset the KAM it will fire right up, run normally, and even let me drive it around until its warmed up. Once its warm, if I shut it down then restart it the problem presents. If I let it cool off for hours and try to restart it, problem is still present.
Some more info on the truck, it's got a "cold" air intake that I've begrudgingly kept on because I can't find a junkyard air filter box and tube to revert to stock. Its relearned idle and drive trims before with the CAI, but I'm wondering if the MAF isn't getting along with it anymore. I replaced the MAF a month ago with a new ford one, and put a dry cone filter on to replace the oiled k&n, and it was working well before the rebuild.
The IAC and TPS are also ford and less than 3 months old, and were both working up until the rebuild so I'm assuming they're good.

 

So I started it up to test a few things. Ran fine at first as usual, and now I've got every PCM PID I can think of that might be related open in forscan to see what's what. I'll attach the file so anyone with forscan can take a look or open it as a .csv

I noticed the fuel trims got bad real quick. At start it was ‐20 stft and dropped to 0 within 10 seconds, but ltft went from 0 to positive 20 and stayed there for the duration of my idle test. Possible leaky injector or?

Spark advance was 22-25° the whole time.

Vacuum was stable, but stayed at 17in/hg which is low. No vacuum leaks per carb cleaner testing.

At 273 seconds I had run a minute in idle with ac, without ac, in gear and in neutral. I pulled the IAC plug and it went to die immediately so I plugged it back in. From that point on I got the p0320 and also the surging idle, like it couldn't recover and was hunting for stoiciometeric A/F ratio. Knock sensor lit up and I started getting camshaft sensor faults.

 

I remember when a shop accidentally reversed upstream O2 sensor plugs on a neighbors car, ran OK until warm up and PCM started to use the O2s, lean and rich at the same time, took me awhile, there is only 1 wire color difference on some years, and plugins are universal
Not sure if that can happen on your year
In this vehicle both plugins where at the top back of engine and he had a new clutch installed so "Y" pipe and O2s were disconnected to do the work

 

The o2 sensors are correctly connected, however after I installed the engine and had everything wired and started it for the first time, I checked o2 sensors due to the symptoms. The bank 1 downstream sensor had some oil drip on it and make it's way into the plug. I was worried I had damaged it running voltage through with the oil in there, so I swapped it out and also DMM'd it against a known good sensor but got no change, sensor checked out.

Some more info I've got. Fuel system bank 1 had been able to enter closed loop numerous times during testing, but bank 2 PID is showing error and hasn't changed through testing.

When I reinstalled the fuel rail, I replaced the bank 2 rear fuel rail cap that was on there with a fuel pressure damper that was installed on this model year engine. I am gonna go ahead and pull the upper intake and swap the pressure damper out for the rail plug and see what happens. I don't know how it could cause an issue but it's one of the few things I changed when doing this project that wasn't a direct replacement.
While I'm at it I'll check the injector wiring and anything else I can associated with bank 2 fuel system. Anything specific I should look for? PID says error but there's no associated codes.

EDIT*
Apparently, ford didn't use a separate fuel system for each bank, they are both represented by bank 1 fuelsys, the error code is just forscan saying there is no sensor for fuelsys bank 2. At least that's what I gather from the help section on the forscan site.

 

There is no fuel sensor on either bank or in the tank, PCM assumes 55psi pressure
So not sure what you are reading?

Bank 1, passenger side, should have a damper, nothing on bank 2 but the IN fuel line and the crossover to bank 1

I don't think a damper would hurt anything on Bank 2

 

Yeah I should have phrased that differently​​​​ . The PID for Bank 1 says its entering closed loop, but the PID for bank 2 isn't, just says error. O2 sensors are working based on the PID for each sensor.

Here's how the fuel rail looks



Passenger side had the Schrader valve, driver side had a cap. I replaced the cap with the damper, service manual says it gets one. I figured since the damn thing cost $150 the PO just deleted it when the diaphragm leaked. I'm still considering taking it back off just to see what happens. I'm kinda running out of ideas.
I'm still waiting on the crank sensor. Fingers crossed that it is the culprit but I'm not too hopeful.

 

Just thought I would throw this in there if I had to find a problem on my 97 3.0. I couldn’t even get a .004 feeler between the plate and the bore of the throttle body, opened it up to .010, unplugged the battery cleaned the original IAC Started it up and let it learn. No more wandering...
Larry (Harmony162)

 

Did you ever find out the problem? I am seeing a similar one.