E4OD shifting wierd...

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Nov 16, 2009 | 09:01 PM

SMS888

Thread Starter

Junior User

Joined: Jan 2006

Posts: 96

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From: West Haven, CT

E4OD shifting wierd...

I have a '94 F350 7.3 Turbo IDI with 196,000. The engine runs great, but the trans has been shifting wierd. The e4od shifts perfect around town but on the highway cruising at 70 it seems like it either downshifts or unlock the tc. The rpm's don't rise enough to be a downshift to 3rd, so I figured the tc was unlocking. Fluid is fine. I have to change the speed sensor for other reasons, could this be the reason? Also my speedo floats between 66 and 69 mph. Anything to do with that? Thanks

Steve

Nov 17, 2009 | 10:53 PM

peboiteau

Freshman User

Joined: Jun 2008

Posts: 42

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Hi,
My truck does the same, but on 2nd, 3rd and 4th, around town or on hwy.
Have you figured out what was the problem?

Nov 18, 2009 | 08:03 PM

78fordman

Cargo Master

Joined: Oct 2003

Posts: 2,833

Likes: 4

From: Jefferson, Iowa

check your brake switch, usually when you hit your brakes your tc unlocks, if it is having problems, ie brake lights flickering, it could cause the same problem. Something i would check before throwing parts at it, get a wiring diagram and see which two wires go to your tc lokcup selonoid, tap off of those two wires, run them up to the cab and put your volt meter on them while driving down the road. When cruising with the engine warmed up, you should have your 12 v constant. If the 12v signal is coming and going, double check your brake switch and wiring between your pcm and your transmission. I doubt it is your speed sensor, due to your not in "limp" mode, usually your transmission will have higher shift points and higher line pressure to "limp" you home. If you do maintain 12v the entire time the truck is doing this on your tc lockup selonoid. Your probably losing line pressure somewhere or your tc return circuit may have a blockage, but its best for a tranny shop to check it out.

Nov 20, 2009 | 09:27 AM

mprice

Elder User

Joined: Feb 2007

Posts: 601

Likes: 1

From: Chicagoland

Quote:

Originally Posted by SMS888

What's the issue with your speed sensor? The E4OD depends on that signal being clean so if it's wonky that would definitely cause issues. The ECU is smart enough to multiply engine revs by the gear reduction and compare that to the revs coming back from the speed sensor to check for slippage in the tranny after tc lockup. If you already have confirmed a problem with the VSS I'd change that first before worrying about the tranny.

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