Another please help Dr. Kovalsky post - PowerStrokeNation : Ford Powerstroke Diesel Forum
 
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post #1 of 3 (permalink) Old 10-28-2014, 02:27 AM Thread Starter
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Another please help Dr. Kovalsky post

Here is the issue, when on the highway, or occasionally around town, the trans will rapidly drop out of OD, and then shift back up. It happened to me the other day about six times within a 5 minute period on the highway, speed was 65 mph, flat ground, and constant throttle position, after the little fit, it stopped and did not happen again for the rest of the trip, about 10 miles.
Truck has 217k on the motor.
The trans is a fresh rebuild, from a reputable builder, with less than 5000 miles on it.
Trans fluid is less than 2k miles old, and is mobil 1. synthetic.
Did a pressure check, all of the readings are well within specifications, most are slightly on the high side.
All of the brake light bulbs are working.
Did a scantool switch test, all of the switches appear to be working.
Checked both of the connections at the solenoid pack and the mlps, neither show signs of moisture or trans fluid on the pins, both have been dielectric greased.
I have not checked the tps voltage, nor the mlps voltage yet.
Speed sensor is slighly bouncy at certain mph, but 65mph is one of the steady sweet spots.
Trans temperature rarely gets above 180*, only after a long pull up a steep mountain grade with my trailer, and even then it only hit 205*.
Anyplace in particular i can start troubleshooting further?

Chop Cut Grind Weld
96 RC 7.3 auto, rebuilt tranny, 3" dp, 4" to the back, PHP hydra, WW2/1.0 housing, stock injectors and hpop, efuel w/bb tightwad reg return, b-codes w/4" lift blocks, 3.5" rsk and x codes, 34.5" tire
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post #2 of 3 (permalink) Old 10-28-2014, 04:25 PM
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Re: Another please help Dr. Kovalsky post

This is exactly what happens when the MLPS starts to fail. It intermittently will get higher than normal resistance, which the PCM reads as neutral. You can't detect this by checking voltages while parked, it will only happen going down the road.

If you have a scan tool that will let you monitor PRNDL and gear commanded you should be able to see it change from D to N and the commanded gear go to 1.

Mark
Former Ford Automatic Transmission Engineer

“The good thing about science is that it's true whether or not you believe in it.” ― Neil deGrasse Tyson
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post #3 of 3 (permalink) Old 10-28-2014, 04:47 PM Thread Starter
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Re: Another please help Dr. Kovalsky post

Alrighty, i'll get a new one on order. Thanks a ton, I'll let you know how it works out.

Chop Cut Grind Weld
96 RC 7.3 auto, rebuilt tranny, 3" dp, 4" to the back, PHP hydra, WW2/1.0 housing, stock injectors and hpop, efuel w/bb tightwad reg return, b-codes w/4" lift blocks, 3.5" rsk and x codes, 34.5" tire
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