4r100 slips, shifts hard, no codes...
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Senior User
Joined: Feb 2009
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From: Clarksville, TN
4r100 slips, shifts hard, no codes...
The vehicle: 2000 Excursion 6.8L, 4r100, 4x4, 220K miles
The issue: Transmission shifts fine from 1-2 but 2nd and up will hang in the upper rpms if I hold the throttle and BANG! It feels like the motor is about to jump out of the hood. I have only done that once btw...no need to recreate that but I can tell it would do it again and again if I didn't "drive" the truck and let off the gas at the upper rpms to control the shift pressure.
I had an independent shop tell me that 3rd gear is going out and there is a band issue. Honestly, I'm not sure. I'm hoping it's a VSS or something but there are no codes??
Anyone with similar issues that fixed their trans OR do you know of any tests that I can perform to verify what may be wrong? I'd be willing to purchase specific tools if necessary (to a certain $).
Where do I start to find the source of the problem?
Thanks!
The issue: Transmission shifts fine from 1-2 but 2nd and up will hang in the upper rpms if I hold the throttle and BANG! It feels like the motor is about to jump out of the hood. I have only done that once btw...no need to recreate that but I can tell it would do it again and again if I didn't "drive" the truck and let off the gas at the upper rpms to control the shift pressure.
I had an independent shop tell me that 3rd gear is going out and there is a band issue. Honestly, I'm not sure. I'm hoping it's a VSS or something but there are no codes??
Anyone with similar issues that fixed their trans OR do you know of any tests that I can perform to verify what may be wrong? I'd be willing to purchase specific tools if necessary (to a certain $).
Where do I start to find the source of the problem?
Thanks!
Frmr Ford Trans Engr
Joined: Aug 1999
Posts: 24,730
Likes: 2,658
From: SE Florida
.
I'd start with a high end scan tool that has Ford software so that it can read Ford transmission codes. Many (most?) scan tools cannot read these codes, so I'm often told there are no codes, when there really are codes, but they don't know how to read them.
If the codes don't offer any help the same high end tool can be used to look at live data. Is the VSS reading properly? How about the TSS, OSS, TPS, MAP, etc. Is the trans shifting when the PCM is telling it to shift? Is the trans gear ratio correct for the gear it is in?
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Senior User
Joined: Feb 2009
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From: Clarksville, TN
Mark, thanks for the reply.
I am going to pick up the truck this afternoon and will report back exactly what they think is the issue. I was told they did drive the truck and checked live data but nothing came up. I have no idea what data is presented or how to interpret it but I assume this guy either knows and there was nothing or he doesn't know what to look for. Is there anything in particular that would show up, like value ranges for each sensor? or are those automatically diagnosed by the scanner?
Do you have an example of a "high end scan tool" that would diagnose a Ford properly?
Lastly, I failed to mention this before and I apologize if it is significant to answering the issue but the truck idles at 1000 rpm. I'm not sure if that's normal, I assume not and may provide a key to the shifting issue...?
Thanks again for taking the time to read this and provide assistance.
I am going to pick up the truck this afternoon and will report back exactly what they think is the issue. I was told they did drive the truck and checked live data but nothing came up. I have no idea what data is presented or how to interpret it but I assume this guy either knows and there was nothing or he doesn't know what to look for. Is there anything in particular that would show up, like value ranges for each sensor? or are those automatically diagnosed by the scanner?
Do you have an example of a "high end scan tool" that would diagnose a Ford properly?
Lastly, I failed to mention this before and I apologize if it is significant to answering the issue but the truck idles at 1000 rpm. I'm not sure if that's normal, I assume not and may provide a key to the shifting issue...?
Thanks again for taking the time to read this and provide assistance.
Frmr Ford Trans Engr
Joined: Aug 1999
Posts: 24,730
Likes: 2,658
From: SE Florida
1000 RPM is too high. Find out why and fix it before attempting to repair anything on the transmission. The first rule of repairing ANY transmission issue is always fix all engine issues. Quite often an engine problem will cause a transmission shift issue. Fixing the engine problem makes the trans problem go away.
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Senior User
Joined: Feb 2009
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From: Clarksville, TN
Mark, thanks again for the reply.
I've been outside for hours now trying to use the Torque App to help determine what's wrong. No luck as of yet but I did notice the RPMs in the app read normal so I think the truck's gauge is off and it's not truly idling high.
Another thing I notice with the App is the throttle seems to be at 20% at idle and there are a huge number of misfires according to the readout. I haven't figured out how to add #9-10 cylinders PIDs but even so, it doesn't appear that the 1-8 cylinders get a reading anyways...
...back to the drawing board, I guess.
I've been outside for hours now trying to use the Torque App to help determine what's wrong. No luck as of yet but I did notice the RPMs in the app read normal so I think the truck's gauge is off and it's not truly idling high.
Another thing I notice with the App is the throttle seems to be at 20% at idle and there are a huge number of misfires according to the readout. I haven't figured out how to add #9-10 cylinders PIDs but even so, it doesn't appear that the 1-8 cylinders get a reading anyways...
...back to the drawing board, I guess.
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Senior User
Joined: Feb 2009
Posts: 201
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From: Clarksville, TN
Some funny S**T!!! I read somewhere about a guy having the same issue because of a bad alternator. I've suspected the alternator on this truck to be headed out the door and the power wire coming from the alternator has some "heat" damage but it charges fine...or seems to so I haven't thought twice until today.
I started the truck, unplugged the double connector, went for a drive and it shifted hard the first time but then no more after that! I stopped and push the throttle down and off I went. I help the rpms to 3K waiting for the motor to leap from under the hood but it shifted correctly! WTF I asked myslef?
I came home and plugged the connector back in, with the truck still running and went for another ride. There was one time at low speeds it shifted "firmly" but the hard shifting issue I had has seemed to have disappeared. For now!
I did noticed the alternator made some God awful noises when I plugged it back in while the truck was running but it doesn't seemed to have hurt anything.
I started the truck, unplugged the double connector, went for a drive and it shifted hard the first time but then no more after that! I stopped and push the throttle down and off I went. I help the rpms to 3K waiting for the motor to leap from under the hood but it shifted correctly! WTF I asked myslef?
I came home and plugged the connector back in, with the truck still running and went for another ride. There was one time at low speeds it shifted "firmly" but the hard shifting issue I had has seemed to have disappeared. For now!
I did noticed the alternator made some God awful noises when I plugged it back in while the truck was running but it doesn't seemed to have hurt anything.
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