Transmission issues after engine swap.

[Cstoliker]

2000 Xlt 4.0 SOHC 5speed auto (5r55e I believe) Had a garage replace my engine and just got it back. Under full throttle it feels like transmission is slipping. Engine revs real high and there not that much pull. Seams to shift and engage ok under normal throttle. No transmission issues before the swap. Fluid is good.

*UPDATE: I got a better chance to test it and I don’t believe the transmission is actually slipping. I think it downshifts too much and doesn’t upshift under heavy throttle. RPMs get up to 6k.
I am not sure what vehicle the donor engine came from but it does have shuttle differences. For instance, my original motor had individual coils on each spark plug. The new motor has wires.

 

[C420sailor]

Your original engine had COP ignition? Strange....

Any codes? Legit slipping will often throw an incorrect gear ratio code.

 

[974X4BLACKSPORT]

If the battery was disconnected for the R&R of the engine, it is necessary to drive the vehicle moderately for at least ten miles for the PCM to "re-learn" and adapt to the condition of the transmission.
Dont just "WOT" from the get go and run throught the gears, take it easy on the transmission and let it re-adjust. This is also stated in the service manuals.

 

[Cstoliker]

I got a better chance to test it and I don’t believe the transmission is actually slipping. I think it downshifts too much and doesn’t upshift under heavy throttle. RPMs get up to 6k.
Is it a simple cable the transmission uses to sense throttle position or is it controlled by the PCM? If the donor motor was on a 4 speed previously could that be causing the issue?

 

[974X4BLACKSPORT]

Make sure your transmission fluid is full and in good condition. The 5r55e transmission is fully electronically controlled, no TV cable. So long as the transmission was not tampered with in any way during the engine R&R, it should work the same, provided the original PCM is still being used. As the service manual states, when the battery is disconnected, and then reconnected, the vehicle must be driven in a way to allow the PCM to "re-adjust" to the condition of the transmission by driving gently, and gradually applying a more aggressive nature (more throttle during acceleration) as the miles are accumulated. It takes only one event of serious clutch slippage to burn the clutches/ bands to the point they will never work the same again, holding power is lost in the frictions and the shifts will never be the same again unless the frictions and steels are replaced with new ones.
WHen it comes to replacing an engine in an automobile to restore factory function and performance, the only acceptable substitute are parts that match exactly to the make, model, year, and most importantly the "calibration" to the specific vehicle. If these variables are not precisely met as the factory intended, that is when issues arise.

 

[C420sailor]

You’re using the same PCM right? You shouldn’t have swapped PCMs.

 

[410Fortune]

I am not sure what vehicle the donor engine came from but it does have shuttle differences. For instance, my original motor had individual coils on each spark plug. The new motor has wires.

What the heck???

Who is replacing engines here? No way did the old engine have COP ignition....
I would check all the wiring going to the transmission and make sure it is hooked up
Something very fishy going on here.

Is the check engine light on?
Flashing OD light?

in the 2000 model year there was no such thing as an engine with coil on plug ignition in an Explorer.........Only the 4.6 triton V8 had COP ignition and it was not available in the explorer until the Gen III in 2002........and that is a V8!!