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Just bought my 1994 F350 quad cab dually with a 7.3 diesel and E4OD. Most of the time it shifts fine but at times 1st to 2nd hits hard, 2nd to 3rd shifts up and then shift back down several times and in overdrive at 50 to 80 mph will drop back to 3rd acting like it is slipping. The cruise control engages for about 2 seconds. The overdrive light use to flash on and off at slow speeds or at a stop. Changed out the RPM sensor since it was bad which fixed that problem. It had bare wires for about 3/4" above the screw in plug. Was told that was from oil being on them for a long period of time. Any ideas why the weird shifting.  Just wondering what the miles per gallon should be. 4:10 rear end.

Herman.jpg

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Welcome to forums, TxWolf53...Like usual, a code read would be helpful and at least point toward any obvious issues.  As I caution, reinforced by the experiences of members and what they have shared, a code does not always mean, "Oh, let's replace that part!"  Many owners have joined the forums after throwing good money after bad with no success.

Before considering other issues, and based upon the symptoms you describe, I would check out the FIPL (Throttle Position Sensor).  On the 7.3L diesel models like yours, a defective or simply out of adjustment FIPL can lead to shift irregularities like you describe.  Often, a careful adjustment will remedy the issue.  Here is the factory procedure.  Zoom-in for details:

Ford E4OD FIPL Diesel.pdf

Check out the FIPL and try an adjustment first...A code read would be helpful, too.  Let us know what you find.

Fuel efficiency is subjective.  In general, diesels are hypersensitive to rpm.  The 7.3L Navistar/Powerstroke is, in my view, the best diesel option Ford has offered to date.  Fuel efficiency with this engine, however, is more like a medium duty truck application.  If you drive close to the engine's torque peak rpm, or below that rpm, you will be able to get an accurate read on fuel efficiency.  

You should be able to achieve 18-plus mpg when running empty at cruise speeds.  Trailering to 10K Gross should still attain 11-14 mpg at the right rpm.  The 4.10 gears will challenge mileage a bit but this kind of ratio takes a load off the engine and transmission.  

How many miles are on the powertrain (engine/transmission)?  This can impact fuel efficiency some.

Moses

 

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I got a OBD1 from Innova that supposed to have all the Bells and Whistles. It gave me a code for the TPS saying the lever was out of position. I got a TPS from Advanced Auto Parts for $21.64 with taxes (helps working in that industry). Just put it on and will see if that helps. Going to change out the connector also could be in better shape. Only thing that worries me is I read in another forum how to test it using a voltage Gage. Said to turn on the key without starting it and check for 5 volts on position A org/wht wire. B blk/whit wire is ground and C should have 1.2 volts with throttle closed and 4 to 4.5 volt throttle wide open. I am getting .02 to .04 volts on A and 4.98 volts no mater where the throttle is. Hard enough to get to the screws on the TPS but without removing the whole air cleaner area can not even get inner screw on the bracket to loosen it up to turn it

As far as fuel mileage I am getting at best 9.5 mpg on the highway. There are a bit over 177,500 miles on it. The prior owners used it in a Custom home building company dragging a 7,000 lb Bobcat around using a goose-neck trailer. Highway speeds it is turning about 2,500 rpms. 

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Your mileage on-highway, if without a trailer or load, is very poor.  The TPS fix may make a difference here.  Otherwise, it might be worth doing a compression check, as this engine had a good workout for a long period of time.  The 7.3L is known for much longer service life than 177K, some would even argue that this medium duty powerplant in a pickup chassis is just broken in at this mileage.  However, the constant trailer towing with a Bobcat would suggest that your engine has been worked more like a medium duty truck application than a light-duty F-350.

Here are the specs on your engine.  In any case, you're spinning the engine way too fast at cruise speeds for decent fuel efficiency.  Peak torque is at 1400 rpm, peak horsepower at 3000 rpm.  I would want to run this engine in the 1400-2100 rpm range at cruise speed unloaded.  For strictly fuel efficiency, the closer to 1400-1800 rpm the better.  Others may have additional, real-world experience and thoughts.  Here are your engine specs, courtesy of dieselhub.com:

http://www.dieselhub.com/idi/7.3-idi.html

There are examples online of Ford F250/350 owners installing an auxiliary box like the Spicer 5831 behind the transmission/transfer case.  These units provide an underdrive, direct and overdrive ratio.  Depending upon the series, OD ratios of .73 and .85 are available.  (See: http://6066gmcguy.com/spicer-5831-b.html.)  At your current road speeds, the 2500 rpm would drop to 2125 rpm with the .85 overdrive and 1825 rpm with the .73 overdrive ratio.  A considerable project but some find it worthwhile. Another option is to slow down; short of an auxiliary transmission, I find this helps the most.

Another option would be 3.73 axle gearing, however, if you tow weight most of the time, such taller gearing would put a larger load on the E4OD.  Before investing in an auxiliary transmission, evaluate the 7.3L engine's condition (compression, oil pressure, etc.) and tune.

Moses

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8 hours ago, Moses Ludel said:

Your mileage on-highway, if without a trailer or load, is very poor.  The TPS fix may make a difference here.  Otherwise, it might be worth doing a compression check, as this engine had a good workout for a long period of time.  The 7.3L is known for much longer service life than 177K, some would even argue that this medium duty powerplant in a pickup chassis is just broken in at this mileage.  However, the constant trailer towing with a Bobcat would suggest that your engine has been worked more like a medium duty truck application than a light-duty F-350.

Here are the specs on your engine.  In any case, you're spinning the engine way too fast at cruise speeds for decent fuel efficiency.  Peak torque is at 1400 rpm, peak horsepower at 3000 rpm.  I would want to run this engine in the 1400-2100 rpm range at cruise speed unloaded.  For strictly fuel efficiency, the closer to 1400-1800 rpm the better.  Others may have additional, real-world experience and thoughts.  Here are your engine specs, courtesy of dieselhub.com:

http://www.dieselhub.com/idi/7.3-idi.html

There are examples online of Ford F250/350 owners installing an auxiliary box like the Spicer 5831 behind the transmission/transfer case.  These units provide an underdrive, direct and overdrive ratio.  Depending upon the series, OD ratios of .73 and .85 are available.  (See: http://6066gmcguy.com/spicer-5831-b.html.)  At your current road speeds, the 2500 rpm would drop to 2125 rpm with the .85 overdrive and 1825 rpm with the .73 overdrive ratio.  A considerable project but some find it worthwhile. Another option is to slow down; short of an auxiliary transmission, I find this helps the most.

Another option would be 3.73 axle gearing, however, if you tow weight most of the time, such taller gearing would put a larger load on the E4OD.  Before investing in an auxiliary transmission, evaluate the 7.3L engine's condition (compression, oil pressure, etc.) and tune.

Moses

The TPS seems to helped. It is shifting smoothly and no weird multiple up and down shifting. Wish that had taken care of the cruise control. Still drops out in about 5 seconds and a cladding noise from the cruise control on the firewall and the ABS light has been on since I bought it. Did change out the VSS and the connector. Will get the rear-end fluid changed this weekend to see if there is any crud in it and what the tone ring looks like. I topped off the main fuel tank and will see if the TPS change out helps the mileage. Still need to find out where that fuel smell is coming from. I had seen the spicer https://www.gearvendors.com/f2wd4s.html before but at around $3,000.00 not quite ready to spend that yet, maybe later. The 2,500 rpm was on the toil road at 80 mph. It is closer to 2,000 at 60 mph.

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Glad the TPS fix solved the shifting issues, TxWolf53!  What's your fuel mileage at 60 mph/2000 rpm?

The Gear Vendors option has been around for many decades, though Gear Vendors cautions against use of its overdrive with a diesel powered truck that tows.  I considered the GV Overdrive for our Ram 3500, and GV frowned on the idea, concerned that I would use double overdrive while trailering.  (I swore that I'd promote sole use of direct in the GV unit while towing; based on GV experience, they were not convinced that other owners would do so.)  Many users have overtaxed the GV units towing very heavy loads (visualize the nine-horse trailers) in double overdrive.  It's a warranty issue, I'm sure...

The auxiliary transmissions I'm describing are medium and heavy duty truck grade counter gear units.  The 5831 was common in dump trucks run in pits.  Ford optioned these units in these bigger trucks.  Here's one account of the even heavier duty Spicer 7231 B swapped into a Ford F-250 tow chassis, see "Two-Stick":  http://www.ford-trucks.com/forums/587547-a-new-brownie-thread-5.html  These units are generically called a "Brownie" after the original Brown-Lipe design that Spicer later acquired and produced.

An auxiliary transmission like these will require mounting the box between the transmission (2WD models) or the transfer case (4WD models) and the rear axle.  There is fabrication and driveline work involved, this is a significant but in some cases worthwhile project.  May be far easier to slow down, our diesels will run faster but burn far more fuel in the process.

Moses

  

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May have spoke too soon on the shifting. At 65 and up acts like it drops out of gear and rpm jumps to 3,000 or higher before it goes back into 4th. Had the rear-end checked. Some metal shaving but otherwise no problems. Tone ring seems fine. They cleaned it out, refilled it and resealed the cover $150.00 (ouch) I brought in the gear oil and the black RTV. Is a 10:25 4:10 not a limited slip. ABS light still on . Would the trailer braking unit possibly cause the ABS to not work? Tried to get it inspection-ed and they said the rear passenger wheels were locking up. Took it apart and blew out a ton of brake dust and cleaned the area. Still plenty of material left and nothing appears to be broken or leaking.

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The trailer brake controller could be causing an ABS issue.  I'd try disconnecting the controller, clear the trouble code(s), then see whether the ABS light goes out.  Rotate the rear wheels and drive the truck to make sure there is no wheel lockup or brake drag.    

Any signs of heat when you checked the rear brakes?  Were the brakes showing signs of dragging?  

Moses

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