Ok I searched and as far as I found this hasn't been covered. I swapped a S4 TII trans into an S5 GXL which had an electronic automatic trans in it. The car runs great but I can't break it loose or else the cars cuts out or drops rpm. Now when I drive it casually gradually pressing the gas it flies. But when I floor it or drop the clutch it seems like it bogs down. So first of all why am I losing power when I gun it as opposed as to when I gradually push the throttle. The motor is 100% healthy and my 5th and 6th are opening fine. There is no hesitation whatsoever and like I said I can feel the cars power as long as I don't floor it. I understand there are some electronic things I have to deal with and I've heard of something called a kickdown switch. So what can I do to make the CPU think the auto isn't there any more or do I have to get a different one? I have my passenger side carpet pulled up and the EGI box is exposed and I'm wondering if I need to disconnect any of the 3 plugs.

 

Anyone?

 

I'm pretty sure an auto ECU, and manual ECU are different. I think you have to switch to a manual ECU

 

So in theory and this isn't an educated guess, when I put the pedal to the floor would the car try and downshift on its own but there is no auto trans responding. So if the CPU (ECU?) is trying to "kick down" into gear would there be hesitation in the throttle response? Because it seems to me that the car electronically still thinks the auto trans is there and is getting confused when its not responding or if there is some sort of cut off for the fuel in order to keep the rpms down in order to spare the auto trans from any damage?

 

I think the auto trannies had another computer that controlled the tranny and was plugged into the ECU. You need to unplug said computer and see what happens.

 

Same ecu, though the manual ECU has pinouts for the 5spd switch, which is the same pinout for the overdrive switch in the auto ECU. There won't be any issues on the ECU side.

EDIT: You did disconnect the automatic transmission computer, correct? Leaving it connected will make the car run like absolute ***. The computer is in the passenger side kick panel towards the right.

 

Um... No.

And the gear change is more associated with the servo/diaphram in the back of the auto tranny than it is by the comptuer.

The car will however think the auto tranny is still there if you left the automatic transmission computer (NOT THE ECU) plugged in.

Also, the ECU doesn't roll into limp mode to save the tranny.

Look at it this way, the Engine control computer has no idea what speed the tires are moving at, hence it really doesn't know if something is slipping (tires, tranny bands, screwed torque converter, ect). Theres no limp trigger behind the engine on the driveline. Nothing after the clutch (heck im not sure if anything after the OMP) will trigger a limp mode.

 

The car does run like *** and I haven't disconnected the auto trans computer. I picked up 2 and a half seconds on the 1/4 however but it seems the car isn't running at its full potential. And explain how the auto computer still being present would make the car run like ***. I'm not doubting you I'm just curious as to how it affects the car seeing as how you are the only one who seems to know about this stuff around here.

 

Is this the A/T controll?


If so, it's a good thing you said that, I left it plugged in....

 

Yeah I found that today and unplugged it. The hold light stopped flashing and it idled alot better. I'm assuming the problem is something else.

 

Did you remove the secondary throttle plates on the throttle body yet, wire them open, or change to a manual throttle body? They use some delay valves to slow down their opening when you tromp the gas, my guess is that it was demanded by the warranty department to keep transmission replacements to a minimum...

 

The what? Ok now I'm curious. Where are the plates and how do I fix this problem?

 

In this picture, I've done some MSPAINT work and put arrows on them. Pics are from an S5 service manual, but throttle bodies are the same. I'm pretty sure you can just disconnect the "double diaphram" throttle valve and plug the hoses to test if it works. I just completely removed the first set of throttle plates and filled the holes into the throttle bore with JB-Weld as there are 2 sets (one controlled by the throttle cable and one controlled by vacuum). I'll see if I can find a cable for my digital camera and post a pic of my throttle body if you still don't see what I'm talking about. They are the first set of throttle plates in the upper two bores with the intake pulled off...