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Discussion Starter · #1 ·
just like title says, 96 F350 2wd dually, rebuilt trans, new VSS, new gear lever position switch (or neutral safety, whatever you wanna call it), new solenoid pack and new torque converter. it's throwing these codes:

P0238 Turbo boost sensor A circuit High
P0478 Exhaust pressure
P0470 Exhaust Pressure sensor circuit
P1728 Trans slip error - converter clutch fault
P1211 ICP Pressure above/below desired

I'm guessing the 1211 is a separate issue/stage 2s with stock HPOP, and I would think the trans error would be independent of back pressure stuff. But I cleaned out the up-pipe on the EBC sensor (front passenger manifold), and truck smoothed out and shifted great about 20 miles to work, but leaving home, it started loping and hard shifts again. found another tube, cleaned it with ultrasonic and a speedo cable, also popped on a spare sensor, and same thing, worked great for ~30 miles, then started acting up again.

Also, before I was doing this I cleared the codes, and it drove fine for maybe 2-3 miles before it started acting up again, so I know the computer's trying to compensate for something, I just need to figure out where to slap it to keep the dang thing in line!
 

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Discussion Starter · #2 ·
Bump...Anybody? I've got a spare engine wiring harness that I was gonna try for kicks.
 

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Demon Dually
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The boost sensor could be an indication of a bad MAP sensor which could cause fueling issues. The hard shifts and the torque converter slip code tell me that either you got a bad converter or the solenoid pack is bad, but I would go with bad converter. That would cause the trans to go into limp mode and give full line pressure to the trans causing the hard shifts. You will burn up the trans driving it that way.
 

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Discussion Starter · #4 ·
I brought it back to trans shop last week, and they road tested it with a Aux Trans controller, to take the trans out of the loop, and were able to shift everything fine up and through the recurring issue, and don't think there's anything wrong with the trans or TC

I also changed out the engine wiring harness, which seemed to help, but moreso it just gave me more miles in between screw-ups, so now I typically go 40-80 miles (although a couple times over 100).

I thought I got lucky one day when the engine died on the road, and I found the fuel heater grid all screwed up and shorted, but even after ripping that thing out, it still has the same issue.

One other thing to mention, at medium cruising speeds, like 30-50 ish, the speedometer will flutter maybe 5-8 mph, although it feels like the vehicle speed is steady, maybe a loose rearend? there are times when it jolts and whatnot, similar to bad ujoints, but I've got new ujoints in there

I'll give the MAP a shot, although I wouldn't of thought that could play a role?
 

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Demon Dually
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OK I know what your trans problem is now for sure. Now that you mentioned the speedo fluctuating. The PSOM in your instrument cluster is bad. That will cause every one of the symptoms you have with the truck including the hard shifts and loping. You are going to have to find an instrument cluster. You can pull one from any powerstroke equipped vehicle including the vans. They are interchangeable. You can go to a junk yard and ask for one with mileage close to your or if you don't care about the mileage showing then any cluster will do.
 

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Discussion Starter · #6 ·
I have a spare...will try that, thanks!!
 

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Discussion Starter · #7 ·
OK, so far so good on the PSOM...been about 40 miles and still feels good, keeping my fingers crossed (and knockin on wood...)

Also, my truck is now 50k miles newer :peeman:
 

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Demon Dually
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Glad to hear it's running good. I always forget about that dang PSOM in the cluster. My work van did that once and what a pain in the a$$ it was to figure it out.
 

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quick question and not trying to steal the thread but im to am also haven kinda the same problem. but my speedo dont jump around. lopey idle only at start up and hard erratic shifts..... somtimes everything works good sometimes it doesnt and also i have to CEL.
 

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Discussion Starter · #10 ·
have you checked codes? I never had a CEL, but a few things I had already tried were the Gear Lever Position Sensor (sometimes called the Neutral Safety Switch), the speed sensor, and the crank position sensor.

You can try clearing the codes and see if that does anything...if it's something stupid electrical, it might run OK, then after a while it starts to fck up and PCM goes into some flavor of limp-home mode b/c it's thinking there's a problem. If that doesn't do anything you might have something 'hard' wrong, like the solenoid pack in the tranny, torque converter, etc... But I'd start by running the codes, see what they are, then clear em and see if that changes anything
 

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ok thanks
 

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hum what and where is the PSOM ??
 
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