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C-6 upshift

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Old Jun 27, 2018 | 02:41 PM
  #1  
Peter A.'s Avatar
Peter A.
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C-6 upshift

Once again I am at the mercy of the combined experience of the forum members. I switched engines from 6.9 to 7.3 w/C-6 transmission. The transmission functioned at an acceptable level for the last 25 years that I have owned the truck. I just finished an engine swap to 7.3. Runs great, more power ! Knowing that the VRV is an unavailable item, I took special care to insure that the VRV was stashed in a safe place for the last 8 months, so that I would not have any problems with it on the new engine. It was functioning correctly before the engine swap. Here's the rub...... I have installed the VRV on the 7.3, and adjusted it to the required specs. [ done this 3 times to make absolutely sure that it was a correct adjustment ] . The 1st to 2and upshift is fine. he shift into 3rd gear does not happen until 46 mph, and if you give it any pedal pressure, it tries to downshift back into 2and gear.
I definitely need some assistance with this. It doesn't make sense to me !

Peter A.
 
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Old Jun 27, 2018 | 03:43 PM
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sounds like the downshift linkage is partially in downshift mode.
 
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Old Jun 27, 2018 | 04:03 PM
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Possibly ! my previous problem was the downshift rod being restricted by the Hypermax air filter mount . Their fix was a special rod from them for 65 dollars plus shipping, and a partial removal of the turbo. Not gonna happen at this end ! I just disconnected the rod.
Peter A
 
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Old Jun 27, 2018 | 05:13 PM
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In addition , I just checked the vacuum to the modulator valve. It won't hold vacuum. I went so far as to get under the truck to check it at the valve. Nothing !!
Would this be the problem ??? I noticed that there are different colored valves. Which one fits a 7.3 with a C-6 ? The guys at Napa are clueless.
Peter
 
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Old Jun 27, 2018 | 06:02 PM
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i believe the black band is for diesel applications. my 88 currently has a green band in it and late shifts only after i let off the throttle a bit.
one of these days i have to find the other modulators i have out in the garage and fix it.
it is only a back up snow plow now though as it has 495k miles on it.
 
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Old Jun 27, 2018 | 08:43 PM
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Wouldn't you be able to adjust the late shift out, if it's an adjustable modulator ? Given the fact that mine will not hold any vacuum, I have to replace it with one that will. I wonder where we could get the exact information about the color code application ? I can't call our local Ford dealership as they know nothing about Ford idi's. The oldest tech that they have is younger than my truck.
Peter
 
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Old Jun 28, 2018 | 07:19 AM
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with the proper adjustable modulator, yes it is possible. but since it is no longer a daily driver i can't be bothered messing with it. at my age and current health condition, is is more work getting under the truck to fix it than it is worth.
 
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Old Jun 28, 2018 | 08:36 AM
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You're preaching to the choir. After this engine swap I feel like I'm part of the walking dead. Even so, I'll be going to town today to pick up a new modulator. One that holds vacuum will be better than what's in there now. Who knows, I may luck out by just replacing without adjustment.

Peter
 
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Old Jun 28, 2018 | 02:43 PM
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I think I might be on to something. The vacuum regulator valve on an early 6.2 GM diesel looks to be the almost identical part as our VRV's. With the only difference being the position of the vacuum ports. I got a picture of a Stanadyne pump for the 6.2, and the VRV mount and actuating shaft with pin, appears to be identical to ours. Has anyone ever looked into the possibility of using the GM VRV and re-routing the vacuum lines, or turning the top of the valve towards the back of the vehicle ????

Peter
 
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Old Jun 28, 2018 | 04:59 PM
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https://www.ford-trucks.com/forums/1...eed-a-vrv.html
 
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Old Jun 28, 2018 | 05:13 PM
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Originally Posted by Peter A.
I think I might be on to something. The vacuum regulator valve on an early 6.2 GM diesel looks to be the almost identical part as our VRV's. With the only difference being the position of the vacuum ports. I got a picture of a Stanadyne pump for the 6.2, and the VRV mount and actuating shaft with pin, appears to be identical to ours. Has anyone ever looked into the possibility of using the GM VRV and re-routing the vacuum lines, or turning the top of the valve towards the back of the vehicle ????

Peter
it has been tried a few times and no go. there is just enough of differences for it not able to work.
 
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Old Jun 28, 2018 | 05:19 PM
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Reality !

Seems that the forum has been going around in circles about this for quite some time. Question.......Has anyone ever attempted to mount the GM valve on one of our injection pumps, And if the answer is yes, then why did it not work
Peter
 

Last edited by Peter A.; Jun 28, 2018 at 05:21 PM. Reason: answered question
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Old Jun 28, 2018 | 05:26 PM
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Thanks Tom for your quick response. I think that we were both typing at the same time, and got crossed up. I think that I'm going to buy a GM valve and try to make it work.
Peter
 
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Old Jun 28, 2018 | 06:14 PM
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save your money. it will not mount to the injector pump.
at least 4 guys have tried it, and when it did not work they tried using parts from the chevy valve to get their old ford valves working again.
this is the only known source of ford VRV's available, but they are in Kuwait:
https://www.surplusstockworldwide.co...NTR-E5TZ7B200A
 
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Old Jun 28, 2018 | 07:15 PM
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Thanks again for your insight Tom. That was the big unknown. That answer puts the whole GM valve possibility to rest. I'm going to install the new modulator in the morning. Hope that a new one will take care of the late shift problem.

Peter
 
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