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1988 Ford F-350 7.3L IDI, 1996 Ford F-250 7.3L powerstroke
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Discussion Starter · #1 ·
My 88 has the 7.3 IDI with a C06 automatic 2WD tranny is there away I can use a different transmission instead of a C06 tranny
 

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Yes, you could go with an E4OD. You'd need to get the sensors and TCM to control it or use a stand alone controller. You could also convert to a ZF5 manual transmission.
 

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1988 Ford F-350 7.3L IDI, 1996 Ford F-250 7.3L powerstroke
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84 Posts
Discussion Starter · #3 ·
Ok interesting the reason I am asking is the transmission in it now sometimes my rpms have to be close to or over 3000 in order for it to shift. I have changed the Adjustable vacuum modulator. I really don't seem that, that part fixed anything. I'm thinking it's gonna be internal issues.

I don't understand what you mean by a stand alone controller? How much does it cost for those other transmission a reman I would good with instead of brand new.
 

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Unlike the C6 (which is all mechainical/vacuum operated), an E40D transmission is electrically controlled transmission, so it needs an electronic controller for it to work.

Sent from my SM-S908U using Tapatalk
 

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I'm not familiar with the c-6/diesel set up. There has to be some way that it controls vacuum, it sounds like it isn't getting a signal to the vacuum modulator. The Mercedes I had used mechanical linkage which was a b---- to set. There has to be something controlled by RPM (tach reading) mechanical, or wheel speed. Whatever it is, it will open a valve to the modulator to give it the vacuum it needs from the vacuum pump, same place all of the vent controls and power brake booster gets vacuum.
 

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There has to be some way that it controls vacuum...
No, the early C6s use a vacuum modulator. Later ones (like my '93) use a kickdown cable. I'm not sure when the change occurred.
 

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I didn't even know they still made the C6 in 93. Thought everything had gone electronic by then. If I remember right they all used a kickdown linkage for down shift, but modulator and governor for up shift. The governor controlled the shift, the modulator softened and caused an earlier shift by changing the action of the governor . Under heavy acceleration the shift is delayed by the engine's natural lack of vacuum then being controlled mostly by the governor. With diesel the vacuum remains constant unless there is some way to hold that vacuum off. If the vacuum stays off, then there will be a delayed shift just like under heavy acceleration, or like the vacuum hose fell off because the shift is then controlled only by the governor.
 

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All C6s used a vacuum modulator. The last C6 was built in 1996. They were available in certain F and E series vehicles through the end of the 1996 model year.
 

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1988 Ford F-350 7.3L IDI, 1996 Ford F-250 7.3L powerstroke
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Discussion Starter · #9 ·
So I checked the vacuum modulator line and it's connected to the modulator. So when I start the pickup sometimes when I look at my tach it's moving when I turn it over sometime it doesn't move but when I am driving the tach like bounces up down it does not stay steady like I think it should. Is there a sensor for the tach? Where is it located? The engine is a 7.3 IDI?
 

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It is located right in front of the injector pump on the timing cover that the pump bolts to. A large hex. nut with two wires coming out of it. It is possible that it just needs cleaning. That's a good place for sludge buildup.
 

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It took me about an hour to remember back to 1976 when I last worked on a transmission.
 

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1988 Ford F-350 7.3L IDI, 1996 Ford F-250 7.3L powerstroke
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Discussion Starter · #12 ·
Yeah that was along time ago. I wasn't even thought of. Lol after I replaced the modulator it would sometimes keep doing what it did but now for the last 3weeks I need driving it again I haven't had any issues. But I'm still saving my money for another transmission if I need to replace it.
 

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1988 Ford F-350 7.3L IDI, 1996 Ford F-250 7.3L powerstroke
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Discussion Starter · #14 ·
I replaced the vacuum pump before I started having trouble with the transmission. The pulley was shot on it. And I double checked all my vacuum hoses and there all connected.
 

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The C6 is...better than the newer electronic ones.
Ford designed both, and doesn't seem to agree with your opinion. Historical statistics also disagree with you.
 

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Ford designed both, and doesn't seem to agree with your opinion. Historical statistics also disagree with you.
The C6 is still easier to work on, has fewer things to go wrong, and doesn't depend on any electronics to operate. In my book that makes the C6 the better transmission. My preference, however, is the ZF5 manual transmission.
 
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