When I bought my 94 IDI turbo, I was getting a lot of black smoke on take off and a lot of black smoke anytime I would lug it at all. EGT's would climb over 1200 anytime put a load on it.
I turned the pump down one flat and the smoke was much more reasonable -- a little on take off and a bit when I lugged it. I didn't lose any power and fuel mileage was about the same so I thought it was good. EGT's stayed 1200 or below even under heavy load.
I took it on a trip, pulling a pretty heavy toy hauler and some time during the trip something changed. I get no black smoke under any conditions and power is off.
Is my IP on the way out or something else going on?

 

How long have you had your IDI?

I'd say if you've only had it for a few months, I'd say your IP is on the fritz. I bet the PO turned up the IP so that you'd be giddy about buying it, cuz they have a lot more pep when they are rolling coal. But when you tune the fuel screw down a bit (in it's proper place, cuz your EGT's are thru the roof), you learn that 12psi isn't that much and these older engines are not putting out that much power in reality.

However, you should have some power at least.

My concern is possible compression issues due to you running over 1200 for so long. That's a horrendous amount of heat. And it could have permanently damaged your engine. But hopefully it's just a bad IP or maybe the timing is a bit off. Do you have access to IDI timing equipment to do a quick check?

 

Thanks for the reply genscripter. I didn't lose power right away when I turned the fuel screw down -- it ran well for a few weeks after. I don't know what the PO did, but I put a pyrometer on it as soon as I bought it and didn't run it continuously above 1200. I would back off the throttle to keep it down.
I don't have access to timing equipment and not sure I will keep the truck so I hate to buy it. I thought I might experiment with minor timing changes and see if it runs better.
I know this truck will never have the power that a Powerstroke does, but right now it's not pulling any better than a gas rig.

 

<_< Eh, get the timing 'right', make sure you don't have boost leaks/drive leaks, and you can totally beat a 1st gen 7.3 psd. 2nd gen 7.3 psd you get it tuned right.
(For reference, a 'stock' '99-02 7.3 PSD makes ~250 at the crank, like 190 at the wheels. I've been able to get over 200 out of all of my turbocharged IDIs as tested on the dyno. And yes, it pulls really nicely.)

I personally recommend playing with the timing like you do; figure out where it 'likes' it. What feels most powerful is going to be best for economy as well.
If you floor it and get blue/white/gray smoke, it's retarded. Black is either "correct" or "advanced" timing.

Also, remember that due to the turbo, you will want to be running the engine in the 2K-3K range when towing. The turbo can't "clean up" all of the fuel your IP puts out down low in the RPM band, so you get smoke unless you only give it partial throttle.
Once you are up beyond 2200, that turbo should be able to clean up a maxed-out IP, keeping decent EGTs, and push around 10 PSI of boost.
If you can't get that 10 PSI of boost(once you get it pushing a decent amount of fuel), you might have to disconnect the wastegate if it's opening too soon.

 

Thanks Macrob! I do have a leak in the turbo up-pipe, but I haven't been able to find parts to fix it -- any ideas there?