Idle Question?
Thread Starter
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Senior User
Joined: Sep 2001
Posts: 210
Likes: 2
From: Lincoln, Rhode Island
Idle Question?
Being new to the diesel world I have noticed that downshifts by the auto tranny is more pronounced than in my gas powered trucks. However when I come to a stop I notice my RPM's will dip down to 500 RPM and come right back to normal just before I stop. Is this just a downshift and normal for my 97 f-250?
Post Fiend
Joined: Oct 2003
Posts: 5,903
Likes: 1
From: MICHIGAN
Do you mean automatically downshifting or manually?
IS you speedometer a bit jumpy down low?
Does your cruise control work (if have it)?
How are the up-shifts? Smooth and not hanging too long?
The symtoms you describe indicate a VSS going bad or a TC lock-up not letting go.
It is normal for the engine idle to increase when you shift from N to DR or R. Maybe the TRS needs adjusting.
IS you speedometer a bit jumpy down low?
Does your cruise control work (if have it)?
How are the up-shifts? Smooth and not hanging too long?
The symtoms you describe indicate a VSS going bad or a TC lock-up not letting go.
It is normal for the engine idle to increase when you shift from N to DR or R. Maybe the TRS needs adjusting.
Thread Starter
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Senior User
Joined: Sep 2001
Posts: 210
Likes: 2
From: Lincoln, Rhode Island
The tranny shifts smooth and direct, the cruise control does not work at the moment. The speedo works fine no jumpiness. It only happens when I come to a stop and the truck is in drive.
Post Fiend
Joined: Oct 2003
Posts: 5,903
Likes: 1
From: MICHIGAN
This may have something to do with the CC. The VSS and BPA switch are the first 2 things to look at.
The VSS (Vehicle speed sensor) may be loaded with crude. It's located on top of the differential. Remove it and wipe the particles off.
The BPA (Brake applied switch) is on the front of the master cylinder. Remove the connector and ohm across the switch (not the harness). If you have no continuity the switch is bad. You can temporarily insert a wire or paper clip in the harness. The CC should work again.
Change the tranny fluid and filter next. These tranny are a weak link and should have regular maintenance anyway.
The VSS (Vehicle speed sensor) may be loaded with crude. It's located on top of the differential. Remove it and wipe the particles off.
The BPA (Brake applied switch) is on the front of the master cylinder. Remove the connector and ohm across the switch (not the harness). If you have no continuity the switch is bad. You can temporarily insert a wire or paper clip in the harness. The CC should work again.
Change the tranny fluid and filter next. These tranny are a weak link and should have regular maintenance anyway.
Thread Starter
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Senior User
Joined: Sep 2001
Posts: 210
Likes: 2
From: Lincoln, Rhode Island
Thanks for the info, I will check those items out right away. I have heard the the E4OD trannys are the weak link in these trucks. The guy I bought the truck from was the service manager at one of the local Ford Dealerships and he flushed the tranny every year religiously.
