I traded my 90 non ic truck, in nice running condition(but extreme rusted condition) with 160,000 miles- for a poor running 91 non ic dually a few years back. I wanted the dually(159" cab/chassis) for stability while towing.
When I got it, it had a single cylinder mis-fire. I really had no reservations about the engine, as the original plan was to freshen the head(valve job and some minor port work) new gaskets, turbo, nozzles, a little pump tweek etc...
After getting it home, I found that #3 cylinder was dead by cracking injector lines. I took off the rocker cover, and found a bent exhaust pushrod. Before tearing down the engine, I put a pushrod in it. The mis-fire was gone, but the engine was not as smooth as I was used to with my previous truck. I assumed I would find some issue with the tear down.
Anyway, after having the head done, 60# springs, rebuilt stock nozzles, adding a 2nd gen intercooler, 3" tubes, 351 turbo, 4" exhaust, larger supply lines all the way to the pickup in the tank, piston lift pump, new fuel pin, turned fuel screw, and doing the KDP, The truck still doesn't seem fast, even compared with my previous "almost" stock truck. It also is not smooth at idle like my old truck. There is no way it would spin the tires, even when the fuel is maxed and making 35psi boost. just aint right...
It really falls flat(and even sounds strange) when really getting into it. The smoke is heavy, but very grey, not black.
Doing a poor man's cylinder balance test seems to indicate all cylinders are equal in power.
When I did the KDP, the pin was missing, and a few of the gears had marks in them of something(pin) striking them, although the timing marks all still lined up. In fact, I spun the engine a few complete rotations to be sure that the gears spun true. Everything appeared fine. The problem is, I suspect that the crank gear is out of time. It's been so long, I can't remember if I checked that. I've been hearing more and more about shearing the crank pin. I've seen pictures of varying degrees of shift when it happens.
Bottom line, here are my symptoms:
poor starting
rough idle
poor mileage
less than expected power
grey smoke under power
definite sound change and power/ smoke at hard throttle
I suspect the pump and cam are in time with eachother, but the crank is out of time with them. I also suspect that the injectors are spraying outside of the bowls in the pistons when I get the sound/ power change.
So what do you guys think? I'm open to theories here!
I'm sure I'm leaving out alot of the things that Ive checked, but I defineitely missed something with this one. My truck should be much more powerfull and smoother than it is.