Truck Barely Starts, then Idles VERY Rough

[tbonemcniel]

here's the truck:

'96, 250k miles, stage 1's, d66, intercooled, modded idm, TW tunes, 17* hpop. 70* ambient temperature. Have WTS light, tach goes up to 300rpm or so when cranking. Batteries at 12.7 volts. Clean fuel in fuel bowl, HPOP full to the top. My scanner doesn't seem to want to communicate with my truck, I've never tried it with this truck before. No CEL.


ran like champ last month, parked it for a month and a half. Came home last night, took 30 minutes to get it started, had to work the gas pedal some. When it did start, it ran very very very rough, I let it idle for about 20 minutes. It slowly got smoother, but no where near right. Never saw any movement on my EGT guage, stayed at 0. Probe in driver's side manifold. After 20 minutes, it died. Went to bed.

This morning, started truck, it idled very rough for 5 minutes and died.

Today, replaced GPR and CPS. Still very hard to start, and when it does, it runs like crap. Pulled TW chip, no change. Couldn't find a known good IDM, so got one from my local O'Reilly's, swapped it in. No change.

Put Beans modded IDM back in, unplugged fuel bowl heater. Tried again, easiest start so far, (not right though), but ran worst yet. Very rough, pouring out black smoke. Did have a reading on the EGT guage for the first time, around 250-300*. But ran horrible. Smoke was not constant, it would smoke for ~5 seconds, clean for ~2 seconds, and just back and forth. Time was not consistant. Sometimes it would be smoking for 10 seconds.


I'm pretty much at a loss here. I'm way more of a small block guy. But what's a better tow truck for my '93 Lightning than an OBS Powerstroke....

[kanuck15]

Ok id check all your UVCHs and the wiring harness, Seems like your down a bank or something. Also try unplugging the ICP once. It will throw a CEL till you plug it back in

[tbonemcniel]

What are UVCH's?

I just checked all four valve cover harness plugs, they all look brand new. I unplugged the ICP last night (that's the one towards the front of the drivers side head, facing towards the valley right?), made no difference. No oil in that plug either.

[tbonemcniel]

nm, UVCH is under valve cover harness, duh

[kanuck15]

ok, well back to the drawing board. Wonder if your HPOP is starting to die out?

[97Beast]

Originally Posted by tbonemcniel

What are UVCH's?

I just checked all four valve cover harness plugs, they all look brand new. I unplugged the ICP last night (that's the one towards the front of the drivers side head, facing towards the valley right?), made no difference. No oil in that plug either.

Did you pull the valve covers? The gasket is the middle man in the connection. So if its connected on the outside doesnt mean it isnt unplugged on the inside.
Literally just yesterday my good buddy called and described the same problem. Took the valve covers off, sure enough one of the passenger side connectors was unplugged. Plugged it back in and all is well.
We also shimmed it with a Nickel (you can also use a Quarter) to keep it from coming loose again.

[tbonemcniel]

okay, I'll try pulling the valve cover's. I only checked the outside connectors.

The HPOP is like 8 months old. I'm not saying there's no way it's ****, but I kind of doubt it. Full to the top, 8 month old 17*.

[tbonemcniel]

YouTube - Powerstroke Problems

YouTube - Powerstroke Problems

[tbonemcniel]

that's the smoothest it's run, was a lot rougher

[lil o rinny]

Does sound pretty ruff. Dont have any advice for you but wish you good luck.