4.6 is transmission problems
 

Long time lurker on here, but first post.
Apologies first off if this has been covered elsewhere but I couldn't find an answer.

I have a 2003 4.6 is.
My transmission totally shit itself and I've just paid an independent firm £3200 to have the transmission and torque converter reconditioned.

Prior to the problems, if I was driving in manual mode and slowed down at a junction, the gears would only shift down as far as 3rd and stay there.
This problem still exists after the overhaul.

When driving in auto (not sports mode), when I approach a junction there is a very annoying and sometimes violent jolt when the box kicks down to 2nd and 1st gears.
This was a problem before and now after the overhaul.

Anyone with similar experiences?
Any advice would be greatly appreciated.

Dont know nothing about the trans but it sounds as if the control unit is playing up. Thinking about logically the control unit should be getting alsorts of inputs from sensors around the car i.e thottle position ,speed,brakes etc,from these inputs it should determine what gear you should be in and then therefore send a signal to the correct valve in your transmission which should then select the correct gear set. ( experts correct me if I'm wrong!). Not sure where this contol box is tho. Has it thrown any codes up?

Dweeb

Also if you read further down in the e53 forum you will see people with similar issues that were resolved by replacing wiring to the gearbox.:thumbup:

In my experience with two 4.6iS'...when i replaced tranny and torque converter, there was a sensor in the tranny that i also replaced. I've heard from others about similar repairs but they do not replace the sensor and certain issues remain after repairs.

When driving in manual mode and coming to a stop, does it shift itself into 3rd or is 3rd the lowest gear it allows you to shift into? I believe it's common that it shifts itself into 3rd if you're in a higher gear unless you shift into a lower gear.

The rough downshift from 2-1 is a very common issue with the 4.6iS. In my case, a PUMA case was once opened by my dealer...but with zero resolve. They suggested "topping off tranny fluid" but that proved to be useless. The Dinan engine and tranny software helped a bit, it's less frequent but the issue still appears now and then. I've just learned to live with it and compensate accordingly. I believe the 4.8iS received a SIB to deal with it's rough downshift but nothing for the 4.6iS.

I have a 4.6is too and I've had the same problem,I got a new tranny and torque converter as well and after that it lurches forward when I come to a complete stop.
The code I got was a valve body in the transmission.

What sensor did you replace chillwilli?

Some sort of speed sensor (pulse generator/throttle position sensor?)...can't recall exactly. You can either ask one of the forum techs here or contact the dealer parts guys.

If it's in manual shift mode it is default to shift down to third on its own at a stop. You can manually shift it to first, but only at certain speed/ rpm or completely at a standstill. This is the way the tran software is designed.

When you say your trans "shit itself" what do you mean? Did it quit pulling all together or just the problems you describe?

I also have a 4.6 with the 2-1 downshift bang and it is annoying as hell. The only time I can avoid it totally is to run the A/C compressor which raises the idle a few hundred rpm, or just two foot driving when coming to a stop. I'm planning on upping the idle speed via GT1 to see if this cures the problem. I have a feeling it may just work.

-Ben

Yea I've read on this forum that upping the idle a touch can sort these things out.

Can you tell me anything else about this sensor? Lmk
Thanks