Ok guys...I've got a '99 (may 99) 4X4, 145K miles. It's got a stock down tube, 3.5" from there back. Ive been running a Hypertech Power Programmer III for most of its life.

Other than that, the only mods are the Kwik filter, and the turbo waste gate actuator line unhook mod.

What has been happening of late is that when ambient temps have been getting to mid 40's and below, the engine will develop a definate miss until engine comes up to operating temps. If I will let it warm up 15 min or so, no miss is incountered. Took it to a shop to pull codes and here is what I found:

Memeory codes:
P0500 vehicle speed sensor fault...already aware of this will replace sensor.
P0470 exhaust press sensor circuit fault
P0478 exhaust press control valve
P0640 definition not found

KOEO:
P605 Internal ctrl module rom error
P0470 exhaust Pressure circuit fault
P0640 def not found

KOER:
P0476 Exhaust pressure control valve perfromance
P0542 code def not avail
P0640 def. not avail.

The speed sensor I now needs replaced. The exhaust codes...any advice on where to start? and the def. not found.

The site is great and valuable resource.....looking for direction.

 

Fix the speed senor, erase the codes and see if they come back.

 

exhaust codes are more than likely the exhaust backpressure sensor. location on the super duty is front of engine top side near serpentine belt. it has a metal tube that runs down to the passenger side manifold. it gets gummed up with soot. i have tried cleaning them but it didn't work. they are availible at ford, napa, and ebay. i recommend napa.

hope that helps
tim

 

P0640 — MIAH Manifold intake air heater... Circuit open or shorted to ground

 

Thanks for the replies guys....the speed sensor is on the way. I've also ordered a CPS on the recommendation of a mech at our service center. I will try to order the exhaust backpressure sensor tomorrow at NAPA.

Kwik, any recomends on the MIAH? could this possibly be my engine miss at cold temps?

 

Mine is removed. You don't really need it unless you get into sub zero temps and leave it idling for a long time. No it's not a contributor to the engine miss unless it's REALLY cold. How cold does it get in Kansas?
All the glow plugs working?
Does it miss under load? Or at an idle?

 

Definitely sounds like a glow plug or two.

Exhaust backpressure codes are common on tuned/chipped trucks. May not be related to the problem at all.

 

It will miss at idle and underload. Once the truck reaches a certain temp, it will pick up and run normally. Kinda like givin it a shot of nitrous then everything seems normal again.

It can get cold here....sub zero, but for now just temps in the high 30's in the morn and 60's for a high. Just trying to figure out if this was an injector problem or possibly glow plugs. Or could this be CPS related?

 

Well, we all need to carry a spare CPS anyway, you could start there. It doesn't really sound like a CPS this time. It's not cold enough to make a miss from a burned out glow plug, only at the very first start up. Once you are underway then it would run ok. I'm leaning toward wiring harness problems under your valve cover or a failing injector. They come unplugged over time on the inside.
I have a '99 as well. I'm guessing that there was a batch of engines that had the wiring installed wrong. My experience:
https://www.ford-trucks.com/forums/s...d.php?t=278697