1992 E40D Overdrive Problem
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8th Gear
Joined: Mar 2022
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1992 E40D Overdrive Problem
Hi, I have a 1992 4wd f150 with a E40D Trans, a 4 inch lift, 35inch tires, and 3.55 rear gears. I have a problem with 4th gear. When ever my truck shifts into overdrive, the truck won't keep a constant speed and it just start to slow down and when it hits 53MPH, it kicks right out of overdrive. I have replaced the TPS sensor, Neutral drive safety switch, and the rear abs speed senor. I believe that changing my gear ratio should fix this but I thought I would see if it could be something else. Thanks.
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8th Gear
Joined: Mar 2022
Posts: 8
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-Yes I did all this. I didn't have any codes transmission related. The were all EGR stuff.
Fleet Owner
Joined: Oct 2005
Posts: 20,789
Likes: 1,753
From: Kentucky
If any of those EGR codes indicate the EGR position feedback signal is too high you may have a partially stuck open EGR. That can kill power. Since you did address the PSOM that is one less thing to look at. So as others have stated lower gears may be in your future especially if you have a 5L engine.
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Tuned
Joined: Jun 2018
Posts: 458
Likes: 123
From: Arkansas
Hi, I have a 1992 4wd f150 with a E40D Trans, a 4 inch lift, 35inch tires, and 3.55 rear gears. I have a problem with 4th gear. When ever my truck shifts into overdrive, the truck won't keep a constant speed and it just start to slow down and when it hits 53MPH, it kicks right out of overdrive. I have replaced the TPS sensor, Neutral drive safety switch, and the rear abs speed senor. I believe that changing my gear ratio should fix this but I thought I would see if it could be something else. Thanks.
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Cargo Master
Joined: Mar 2010
Posts: 3,338
Likes: 293
From: Laramie, WY
Even with a 5.8L I'd go right to 4.56 myself. I have 33" mud terrains now with 4.10 gears and think I'd like 4.30 better.
Cargo Master
Joined: Nov 2009
Posts: 2,190
Likes: 620
I've got 31" BFG AT's on my F150, with 3.55's, It's drivable, but it's not anywhere close to what I would consider *good* and I'll be dropping it to at *least* 4.11's if not 4.56's (depends on what I can get in a matching ratio set for an 8.8 and the 44 in the front.) 4.30 would be just about right, considering I've got an AOD in it, and the Overdrive is stupid deep, but I haven't looked to see if that's a ratio I can get.
Cargo Master
Joined: Mar 2010
Posts: 3,338
Likes: 293
From: Laramie, WY
I've got 31" BFG AT's on my F150, with 3.55's, It's drivable, but it's not anywhere close to what I would consider *good* and I'll be dropping it to at *least* 4.11's if not 4.56's (depends on what I can get in a matching ratio set for an 8.8 and the 44 in the front.) 4.30 would be just about right, considering I've got an AOD in it, and the Overdrive is stupid deep, but I haven't looked to see if that's a ratio I can get.
Edited to add: For the 8.8 you can get a relatively wider variety of ratios than for the front axles, including 4.30.
Cargo Master
Joined: Nov 2009
Posts: 2,190
Likes: 620
Last I checked, no 4.30 available for D44 reverse rotation for the TTB's. You can swap in a D50 third member into your D44 housing/beam from a D50 TTB pretty easily, and 4.30 is available for that differential.
Edited to add: For the 8.8 you can get a relatively wider variety of ratios than for the front axles, including 4.30.
Edited to add: For the 8.8 you can get a relatively wider variety of ratios than for the front axles, including 4.30.
Fleet Owner
Joined: Oct 2005
Posts: 20,789
Likes: 1,753
From: Kentucky
What are the EGR codes, by number, and when were they displayed? If the EGR is partially stuck open you are running lean which causes a power loss. Even with the lift and 35" tires a 5.8L engine should be able to go into 4th gear on a flat road even with some headwind.
My old 1992 F350 4x4 w/5.8L engine, 3.55s and 33s had no problem running in 4th gear at highway speeds unloaded and a flat road. Even when pulling my 18 foot flatbed trailer and skidsteer it would stay in 4th gear on the flat and no heavy headwinds. The engine in that truck was not the healthiest but moved it along pretty well.
I am saying this to prevent someone from going to expensive gears to find out the OD issue is still there.
My old 1992 F350 4x4 w/5.8L engine, 3.55s and 33s had no problem running in 4th gear at highway speeds unloaded and a flat road. Even when pulling my 18 foot flatbed trailer and skidsteer it would stay in 4th gear on the flat and no heavy headwinds. The engine in that truck was not the healthiest but moved it along pretty well.
I am saying this to prevent someone from going to expensive gears to find out the OD issue is still there.
Lead Driver
Joined: Jun 2021
Posts: 5,221
Likes: 805
Well my first thought is something obvious which would be that your truck is geared to high, and has too large of a tire for it to maintain speed in OD. What engine is in it? How does it run? I have a stock 2wd 94 with a 300 i6 and with a 3.08 rear end, which you're effectively close too with the larger tire, I have my foot about to the floor to maintain speed on the highway.
I have a 96 with 300 and 3.08 rear and even have dog tracking because my leaf spring is bent. At 70mph with mild to no winds, I can maintain that without having to be to the floor. Although, It wouldnt take much over 70, like 80 or 90, to be there. But I have a stock 15 inch 235 ( ) 15 tires, not sure what you have going on.
E4OD and 2wd, for what its worth.
