Possible 5r110w slip

Reply Subscribe

Thread Tools

Search this Thread

Jan 18, 2026 | 09:27 PM

Mykah knabe

Thread Starter

Mountain Pass

Joined: Dec 2024

Posts: 151

Likes: 61

Possible 5r110w slip

2005 f350 v10. 140k miles. Tonight while accelerating onto the highway where I usually do, the rpms went up to 2500 too easily, and the truck did accelerate and gain speed, but a little slower than normal. I put in the amount of throttle that usually gets me 2200 rpms and up to 50 in around 400 meters, where as this time the same amount of throttle got me up to 2500 rpms and only up to 40 in the same place. No noticeable slip yesterday (someone else did drive the truck for around 8 miles, but I assume that wouldn't effect shifting) the truck sustained highway speeds (55) at the usual rpm. Also later when accelerating onto the highway in a different spot, I pushed it to 2900 rpms and it climbed the decently sized hill well with good acceleration and got up to speed like usual. Could the computer just have glitched and not sent enough line pressure or didnt shift at the right time or som? Hopefully its that😅

Jan 19, 2026 | 09:58 AM

Mark Kovalsky

Frmr Ford Trans Engr

Joined: Aug 1999

Posts: 24,741

Likes: 2,669

From: SE Florida

The first step to diagnose what's wrong is to read the codes. Anything else is just guessing.

The best way is to get Forscan. It's a free download at www.forscan.org. Their page shows how to select an adaptor to plug into the OBDII port.

If you don't want to do that, a good independent shop should be able to read the codes, or a Ford dealer can read them. The auto parts stores that read codes free CANNOT read Ford transmission codes.

Jan 19, 2026 | 05:00 PM

Mykah knabe

Thread Starter

Mountain Pass

Joined: Dec 2024

Posts: 151

Likes: 61

I have access/ability to use a really fancy snap on diagnostic system, would that work or would it still not read ford transmission codes? Second, no issues accelerating today, throttle input matched the rpms and speed increase was excellent.

Last edited by Mykah knabe; Jan 19, 2026 at 08:24 PM.

Jan 19, 2026 | 09:08 PM

Mark Kovalsky

Frmr Ford Trans Engr

Joined: Aug 1999

Posts: 24,741

Likes: 2,669

From: SE Florida

If it has the right software it will read the codes.

Jan 22, 2026 | 12:38 AM

Mykah knabe

Thread Starter

Mountain Pass

Joined: Dec 2024

Posts: 151

Likes: 61

Ok ill look into it and try it. Ill update soon.

Feb 4, 2026 | 09:14 PM

Mykah knabe

Thread Starter

Mountain Pass

Joined: Dec 2024

Posts: 151

Likes: 61

Ok so the diagnostic system didnt find any transmission codes. Just a transfer case code (my auto hubs dont work, not concerned) and an abs module communication error. (Both are codes i was aware of from another scan around 9 months ago) Other than that, nothing. But now the transmission seems to be acting up more. Now as I accelerate onto the highway, it starts off great, engine rpms climbing steadily with vehicle speed. But around 2nd or 3rd gear, once the rpms pass 2250, the rpms begin to climb faster than they were, i have to let off about 5% throttle to keep them from going over my self set " under 2500 rpms when everything's cold" rule, which it usually never does with the throttle amount i use. The vehicle speed increases thru all gears, but im wondering if the clutches are slipping once more load is applied?

Last edited by Mykah knabe; Feb 4, 2026 at 10:28 PM.

Feb 5, 2026 | 07:14 AM

Electroyun

1st Gear

Joined: Nov 2025

Posts: 1

Likes: 0

Possible 5r110w slip

Hi Mykah knabe,
I suggest that you look at FICMrepair.com regarding the 5R110 Full Upgrade Kit.
There is a wealth of advice and information there, without having to purchase anything.
I have dealt with FICMRepair many times and strongly recommend this company, their customer service and technical advice is second to none.
I have purchased said upgrade kit and will be installing within the next week.
This will, I am sure, will cure your issue, give Ed a call, he will advise you well.
Best regards,
Ian

See link https://www.ficmrepair.com/index.cfm...rod/prd279.htm