Trans Shifting Issues
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Tuned
Joined: Feb 2004
Posts: 343
Likes: 30
From: Maryville, TN
Trans Shifting Issues
Just picked up an 89 F-350 7.3 IDI.
First question: How do I know if I have a C6 or E40D? It has an Overdrive cutoff switch, so my guess is an E40D but not sure.
It shifts firmly and makes all the gears but it just seems confused about when to shift.
1) I have to get on it a bit and get the revs up a bit and it only seems to want to shift if I lift off the throttle for a second.
2) if I take off easy it shifts at 16-18 hundred rpm but it immediately starts to cycle like the torque converter is locking and unlocking steady, tach bouncing between 12-13 and 18ish. A little extra throttle and its gone.
3) The tach goes to zero if I take my hoof of the throttle at any speed and also at idle.
4) Speedo reads about 7-8 mph fast at 70. The tires are seriously undersized.
Any thoughts?
Bob
First question: How do I know if I have a C6 or E40D? It has an Overdrive cutoff switch, so my guess is an E40D but not sure.
It shifts firmly and makes all the gears but it just seems confused about when to shift.
1) I have to get on it a bit and get the revs up a bit and it only seems to want to shift if I lift off the throttle for a second.
2) if I take off easy it shifts at 16-18 hundred rpm but it immediately starts to cycle like the torque converter is locking and unlocking steady, tach bouncing between 12-13 and 18ish. A little extra throttle and its gone.
3) The tach goes to zero if I take my hoof of the throttle at any speed and also at idle.
4) Speedo reads about 7-8 mph fast at 70. The tires are seriously undersized.
Any thoughts?
Bob
Thread Starter
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Tuned
Joined: Feb 2004
Posts: 343
Likes: 30
From: Maryville, TN
Search for just the right words helped a little. looks like a need to replace the tach sensor, that should fix the tach and shifting points.
But a new one has popped up. I think the tires are the right size at 235/85-16 however, as mentioned earlier the speedo is off significantly.
So question, does the E40D PCM take speed into account when shifting? If so how to I adjust the speedo to fix that up?
Thanks again,
Bob
But a new one has popped up. I think the tires are the right size at 235/85-16 however, as mentioned earlier the speedo is off significantly.
So question, does the E40D PCM take speed into account when shifting? If so how to I adjust the speedo to fix that up?
Thanks again,
Bob
Senior User
Joined: May 2008
Posts: 387
Likes: 1
From: Bald Knob AR
Yes, the PCM uses both engine speed and vehicle speed to determine which gear it needs to be in. Remove the tach sensor and give it a good cleaning and check the wires where they go across the motor for chaffing. If your speedo is reading 7 mph fast you need to pull the little plastic gear off the end of the sensor and go to Ford and get one with one tooth more than the one you have. One tooth equals 7 mph change. More teeth to slow the speedo, less teeth to make it faster.
If it has the OD cutoff switch it's an E4OD, the C6 is not an OD transmission.
If it has the OD cutoff switch it's an E4OD, the C6 is not an OD transmission.
Thread Starter
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Tuned
Joined: Feb 2004
Posts: 343
Likes: 30
From: Maryville, TN
Update:
The Tach (RPM) sensor fixed the tach dropping to zero and the shift hunting under light acceleration. I tried cleaning it, but it required replacing.
I still have to lift my foot off the accelerator to get it to upshift so tonight I'll try adjusting the TPS and also figure out which speedo gear I have so I can get a replacement (Thanks galute).
The Tach (RPM) sensor fixed the tach dropping to zero and the shift hunting under light acceleration. I tried cleaning it, but it required replacing.
I still have to lift my foot off the accelerator to get it to upshift so tonight I'll try adjusting the TPS and also figure out which speedo gear I have so I can get a replacement (Thanks galute).
Thread Starter
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Tuned
Joined: Feb 2004
Posts: 343
Likes: 30
From: Maryville, TN
Getting closer.
Played with the TPS last night, it has a full 5 volts available so that was fine. It was set at 1.58 on the bottom end and 3.60 at the top end. I played with it a little and ended up at 1.21 at throttle off but the top end stayed at 3.58-3.60. It is better but not there yet, I still have to lift my foot off a little to get it to shift. Especially for 1st and 2nd. I think I'll try knocking it down to 1.1 and see how that feels.
Question: not to concerned about it since the TPS increments smoothly and I am not a WOT kinda guy but is the top end adjusted separately to get it closer to 4.50?
Haven't done the speedo gear yet. Have to find one first. Anyone wanna trade a Ford 10.25" 4.56 R&P for a 3.73?
Bob
Played with the TPS last night, it has a full 5 volts available so that was fine. It was set at 1.58 on the bottom end and 3.60 at the top end. I played with it a little and ended up at 1.21 at throttle off but the top end stayed at 3.58-3.60. It is better but not there yet, I still have to lift my foot off a little to get it to shift. Especially for 1st and 2nd. I think I'll try knocking it down to 1.1 and see how that feels.
Question: not to concerned about it since the TPS increments smoothly and I am not a WOT kinda guy but is the top end adjusted separately to get it closer to 4.50?
Haven't done the speedo gear yet. Have to find one first. Anyone wanna trade a Ford 10.25" 4.56 R&P for a 3.73?
Bob
Senior User
Joined: May 2008
Posts: 387
Likes: 1
From: Bald Knob AR
Set the TPS at 1.0 in the closed position. Make sure it's warmed up first. The higher the setting the higher line pressure in the trans is required for a shift and if I remember right 1.0 is the factory setting for it. I don't know of a way to set the high side of it separately. If it gets too far out on the high side your TPS may be bad.
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Tuned
Joined: Feb 2004
Posts: 343
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From: Maryville, TN
Thanks Galute. That did the trick. Actually ended up at 0.98 but it shifts firmly and properly now.
Now on to the next niggly bit
Now on to the next niggly bit
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Joined: May 2008
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From: Bald Knob AR
Glad to hear you got it going your way. I have mine set at .94 as lot of my driving with this truck is at less than 30mph on some very rough roads and I needed shifts at lighter throttle to keep the engine rpm's down.
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