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What went wrong?!? kinda long

1325 Views 11 Replies 7 Participants Last post by  1jamfoster
It has been a while since i have been to this forum, but you have always come through in the past.
My truck just past 68,500 (not a typo) this past weekend and I wasn't sure for a while if it would make it to 69K or not. The rear tank had #1 left over from the winter, the front had #2. I have used Power Service fuel additive from Car Quest for more than two years. Mods are listed in my sig line. Superchip is 50HP.
I took a trip hauling the 10,000# 5er over the holiday. Just over 300 miles one way to Fairbanks on the Parks Highway. Lots of hills. Twice, within a few miles from home, the truck just *died* when I was slowing down for red lights. While on the front tank I found that going up some of the steeper hills I would get hesitations, bucking/vibrating, and could not get it to run over 30 MPH, and it really hated down shifting into 2nd gear. No real smoke either...just really rough. Once, I downshifted out of overdrive to pass another rig @ a top speed of about 65 MPH. Just as I pull back in, it starts to hesitate and would only go about 50 MPH (flat road) for about 3-4 miles, then it was fine. I noticed all gauges fine, but my pyro dropped down to 350-400 during this time...that has never happened before. Switched tanks somewhere at this time. Further down the road, while cruising at about 63-64 MPH the truck just died. All gauges shut down...nothing. Shifted into neutral and coasted to a safe stop. Would not fire while coasting. Once completely stopped, it fired right up. Made it the rest of the way to Fairbanks without any more problems (about 50 miles).
I spent the weekend in Fairbanks and did a little tinkering. I have a CPS in the glove box, but this really seemed fuel related so I did not replace it yet. I drained the fuel bowl half way then pulled the had 5,000 miles on it. Looked like some fine black particles in the bottom of the bowl and the filter was somewhat black. Went to NAPA and got the *special Price* WIX filter for $38. Filled up with #2 in my two empty tanks.
The truck ran flawless the rest of the time. I did NOT use the Power Service additive in either tank. Power uphill, in 2nd gear on downshift, stayed at a steady 40 MPH up the steepest hill (it use to do 45MPH on the same hills with the same 10K# 5er, but heat made me back out of it...still had power though.
I normally get about 13 MPG when not hauling, and 10 MPG when hauling. It has been this way since I have done all my mods. This time (without the additive) I got 8.3MPG on the way home. Otherwise, it ran smooth as a top, quiet as a Powerstroke can be, and no bucking.
I figured it was a fuel problem from the get go. Probably some of the crap they call diesel at one of the stops I made was part of the problem. The other is the #1 left over from the winter. I think the filter change was what helped...but since I didn't use the additive, I can't rule that out 100% either. If it was the CPS, I would think it would have just died and never started again.
Any suggestions, questions, or ideas out there? Thanks for any comments.
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It certainly will be easy to check in the morning....
I used tape over my chip, so that is solid. Algae is normally not much of a problem in Alaska as it usually is to cold for it to grow much. Regardless, I emptied the tanks twice and have all new fuel ($125 @ the pump yesterday...eek)
Re: What went wrong?!? kinda long (Updated 6/11)

I can find the IPR...any pics available to find this? As best I can tell, everything seems solid around the fuel bowl region.

I went on another trip, this time only to Denali Nat'l Park. When I am not towing, the truck runs great. These problems only happen when under *heavy* loads and going uphill. I was 2 1/2 hours from home and the truck started to buck and kick at almost the exact same location on the HGWY as before. Going uphill I dropped to 10 MPH @ WOT, turbo would not kick in, manual downshift didn't seem to work, vibration was terrible, black smoke, RPM's in the toilet, NO idiot lights, temp gauge @ N, Pyro down to 600F. At the top of the hill, then started going downhill, any attempt to take it over 50MPH caused a severe vibration. After 3-5 minutes it would just start running smooth again. When I got to the more level road I found a spot to pull off and I shut everything down and *pulled* my SUPERCHIP. Fired right up and ran smooth as a to for the next hour. I noticed that there seemed to be no difference with or without the chip (speed, shifting, performance /ubbthreads/images/graemlins/shrug.gif) After a couple of days in the park I hooked the 5er back up and head home. After 15-20 minutes of driving I started to get the same symptoms of severe vibration over 50 MPH, turbo would hardly kick in, unable to pull uphill.
CONSISTANT FINDINGS: when it acts up, if I stop and turn the engine off for about a minute, then restart, it runs perfect for a short time. If I take it out of OD at the bottom of a hill (usually around 55MPH) it will seem to cause me to have the symptoms come on before the top of the that hill, regardless of how long of a pull it is). If I leave it in OD and let it downshift on its own, it is less likely to act up...but it still does.
After about 30 minutes of this going nuts, then wanting to run @ 70MPH without any problems...I pulled off again and Changed Out my CPS. It was hot, but a lot easier job than I thought it was going to be. Five minutes later it started acting up again, but not quite as bad (but the road didn't have any really steeep uphills).

Could this be transmission related? (Shifting patterns *seem* to cause it to come on.)

Could this be something computerized? (If it was mechanical, like a loose screw) I wouldn't think it be so reproducable).

I am ready to take it to someone far smarter than I, 'cause I can't have it unable to tow. For what it is worth, my mileage went up 2 1/2 gal/mile to almost 11 MPG from 8.3 the previous trip /ubbthreads/images/graemlins/shrug.gif
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Re: What went wrong?!? kinda long (Updated 6/11)

Within 5 minutes of changing out my CPU, (brand new one), it was still doing the same thing. I guess it is possible to have a bad replacement, but the exact symptoms?!? I don't think so.
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