Trans slipping/shifting hard

blackbeauty7.3 · Jan 17, 2024

Hey guys, looking for some insight and help before I take the truck into the tranny shop who did my rebuild to get diagnosed. I have a 96 f350 trans was built in 2015. Im having issue with what i believe is the torque converter. The one that was installed on the rebuild was a precision industries triple disc converter. Back in 2016 i was having issue where it was bucking and going into limp mode and got to around 210* a few times while empty. Changed the trs and it helped somewhat. Then i found a few wires shorted on the tranny wiring i fixed and that helped as well. But it never felt quiet right. fast forward to now, truck lurches and the rpms drop way down to the point of almost stalling completely when i first fire it up and put it in reverse or drive as well as slipping going into o/d. the first 2 shifts are smooth and i barely feel them. I have autoengenuity and forscan scanners to check for codes and other pids. However i have no codes or cel. The od light is not blinking either. Are there any tests i can do to rule out some possible issues? I was thinking maybe the map sensor, barometric sensor could be possible issue? or the trs again? I checked my 3rd brake light and all bulbs as well knowing the issues they cause on the e4od. At this point may be better off bringing it to the pros to diagnosis. Any insight is greatly appreciated!

Patrick Feeley · Jan 17, 2024

MAP and BARO should be reading about the same (as each other) at both KOEO and Idle. Cheers!

6.0 Tech · Jan 17, 2024

blackbeauty7.3 said:
Hey guys, looking for some insight and help before I take the truck into the tranny shop who did my rebuild to get diagnosed. I have a 96 f350 trans was built in 2015. Im having issue with what i believe is the torque converter. The one that was installed on the rebuild was a precision industries triple disc converter. Back in 2016 i was having issue where it was bucking and going into limp mode and got to around 210* a few times while empty. Changed the trs and it helped somewhat. Then i found a few wires shorted on the tranny wiring i fixed and that helped as well. But it never felt quiet right. fast forward to now, truck lurches and the rpms drop way down to the point of almost stalling completely when i first fire it up and put it in reverse or drive as well as slipping going into o/d. the first 2 shifts are smooth and i barely feel them. I have autoengenuity and forscan scanners to check for codes and other pids. However i have no codes or cel. The od light is not blinking either. Are there any tests i can do to rule out some possible issues? I was thinking maybe the map sensor, barometric sensor could be possible issue? or the trs again? I checked my 3rd brake light and all bulbs as well knowing the issues they cause on the e4od. At this point may be better off bringing it to the pros to diagnosis. Any insight is greatly appreciated!

Have you checked the fluid yet? Is it full, burned, overfull, etc?

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blackbeauty7.3 · Jan 17, 2024

6.0 Tech said:
Have you checked the fluid yet? Is it full, burned, overfull, etc?

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The fluid and pan looked fine I also changed the filter thinking that it came unseated thinking that may be my issue but it did not fix it.

blackbeauty7.3 · Jan 23, 2024

Patrick Feeley said:
MAP and BARO should be reading about the same (as each other) at both KOEO and Idle. Cheers!

First one is idle 2nd is key on engine off is that too far apart? Bad map sensor?

6.0 Tech · Jan 23, 2024

Those are fine, they’re reading the same psi wise. Guessing you live at sea level, or damn near?

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lincolnlocker · Jan 24, 2024

Far right map obdII is probably correction factor

lincolnlocker · Jan 24, 2024

Map is reading atmo

lincolnlocker · Jan 24, 2024

Do they both raise under load?

blackbeauty7.3 · Jan 24, 2024

6.0 Tech said:
Those are fine, they’re reading the same psi wise. Guessing you live at sea level, or damn near?

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Okay good news! I’m at roughly 430’

blackbeauty7.3 · Jan 24, 2024

lincolnlocker said:
Do they both raise under load?

I didn’t take it for a ride I will check in a bit and let you know thanks!

blackbeauty7.3 · Jan 24, 2024

lincolnlocker said:
Do they both raise under load?

Went out to plow this morning and they did not move at all while driving. Should they be moving under load?

lincolnlocker · Jan 24, 2024

blackbeauty7.3 said:
Went out to plow this morning and they did not move at all while driving. Should they be moving under load?

This on the 96?

Patrick Feeley · Jan 24, 2024

MAP frequency and pressure should move under load. BARO really shouldn't unless you're going up/down in altitude. Cheers!

6.0 Tech · Jan 24, 2024

blackbeauty7.3 said:
Went out to plow this morning and they did not move at all while driving. Should they be moving under load?

Map should move based on however much boost you’re making. And I think that’s what the map obd pid is on your list. It would actually be boost. So at 10 psi of boost, map should read around 24.8, and the map that reads 0 should be 10. If your map isn’t moving, check the hose for attachment to either the sensor or the plenum. Also check it for a restriction by blowing thru it. If the hose checks out, you could have a bad map sensor, or a massive boost leak. We had one at the shop a few months back that we were dynoing, and it was laggy and Smokey. Put our boost leak detector on it, and the drivers side plenum was leaking so bad, our detector would only read about 2-5 psi on the gauge with full shop air being pumped into it. Also, do you have a boost fooler?

Baro should only move as you go up or down in altitude. It’s not sensitive enough to pick up weather changes, but here in Phoenix, we read about 13.7-13.8 psi.

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lincolnlocker · Jan 25, 2024

Patrick Feeley said:
MAP frequency and pressure should move under load. BARO really shouldn't unless you're going up/down in altitude. Cheers!

Can you monitor that on a 97 and earlier with the app he is using?

Patrick Feeley · Jan 25, 2024

Looks like he's using FORScan, so he should be able to (his screenshots above show them). Cheers!

lincolnlocker · Jan 25, 2024

Ok. I thought it was torque pro.. oops.. and i didnt know how far back monitoring went on the original pstroke.

blackbeauty7.3 · Jan 25, 2024

6.0 Tech said:
Map should move based on however much boost you’re making. And I think that’s what the map obd pid is on your list. It would actually be boost. So at 10 psi of boost, map should read around 24.8, and the map that reads 0 should be 10. If your map isn’t moving, check the hose for attachment to either the sensor or the plenum. Also check it for a restriction by blowing thru it. If the hose checks out, you could have a bad map sensor, or a massive boost leak. We had one at the shop a few months back that we were dynoing, and it was laggy and Smokey. Put our boost leak detector on it, and the drivers side plenum was leaking so bad, our detector would only read about 2-5 psi on the gauge with full shop air being pumped into it. Also, do you have a boost fooler?

Baro should only move as you go up or down in altitude. It’s not sensitive enough to pick up weather changes, but here in Phoenix, we read about 13.7-13.8 psi.

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Thank you for the in depth response. I ran the truck today to pull the torque converter to send out to precision for a rebuild and it ran good doesnt seem like im losing any boost. I will double check the map sensor and see if thats good when i get a chance! thanks!