Bucking after rebuild
 

Hey there my fine df brothers. Long time no post. Just got done with a top end refresh and got a few q's.

98 1500 with a tired 5.2. Found a 5.9 on the interwebs for $350. Bought an rv cam for it, and started tearing down the 5.9. Found that the motor was heavily mistreated. Ridiculous buildup of sludge everywhere for a supposed 150k mile engine, rocker arms corroded and rusted to hell. Got down to the factory cam and bearings, both pitted badly. Hadn't planned on changing bearings. Lost about two weeks while I failed at changing the cam bearings without the proper tool. Finally caved and bought the $150 tool from summit, got those changed. Started putting mocking up the cam and things didn't feel right. Keep in mind the deepest I've been in an engine was a plenum fix. Cams are out of my league, a wee bit in over my head. Long story short, comp sent me a cam for an LA, and the snout was too long. They Sent the right cam, got it in, motor back together, blah blah blah.

Swapped the motors last weekend, and minus a few hiccups, miraculously it started.

My question comes in with how it's performing since. I'm town it seems to run mostly OK, maybe a stumble of some kind. But get it on the highway, and under acceleration it's fine, but when I let off the Throttle it bucks pretty obviously. Throws a few codes, the most likely culprit looks like p1391, loss of camshaft/crank. Does this line up with my symptoms, and is it possible to know which one specifically is the issue, cam or crank? I should have just replaced the sensors while it was out, something talked me out of it. "if it's not broke, don't fix it".

I'm going to try and set the fuel sync at a shop, but want this figured out first in case I have to pull the distributer.

Sorry for the novel lol. Thoughts?

Also - the first thing I'm going to do is disconnect both sensors connections and clean them out. I'm not confident it will fix my problem but it's possible they just got a bunch of crap/dirt/etc in them during all the excitement of the swap.

I have a few questions.
1. Did you use a 5.9L PCM?
2. Did you remove the crank sensor before your pulled the motor and put it back in?

Yes 5.9 pcm
No, did not touch existing crank sensor. What is your theory?

You may have damaged the crank sensor removing and installing the motor

It's possible. My dad was on that end while I worked the crane and he had commented a couple of times how it appeared to be in the way, or how it didn't seem to be lining up. I cleaned both connections and as expected it didn't help. I'm going to pull the sensor off the 5.2 and swap it since it's available to me.

That's a good start :)

Just swapped it out, doing the same thing. Im not able to drive it yet, but just revving in the driveway I can feel it, it feels like a shudder, best I can describe it. I shouldn't have to clear the code right, the code will still appear until cleared but if that was the issue it should be running better?

Swapped the cam sensor off the old motor too. Still no change. I understand I will still likely need new replacements to actually rule them out.

Shouldn't have to but sometimes these trucks are weird. What was your code again?