Thread: D2 TD5 Autobox diagnosis

why dont you run a stall test on it?..., it might point you in the right direction, see attachment here http://www.aulro.com/afvb/2308855-post3.html

Already done, stalls out at 2800 to 2900, this hasn't changed even with all the work done. So not exactly conclusive.
Attached is the engine capture from the run home this evening, more or less same timings and more or less same behaviour.
Didn't get caught by the lights so I had to bugger about a bit to get the revs to drop back from 3000.

Also had the other thing happen, which is that it doesn't seem to lock the torque converter up on the expressway at 90kph, so sat at about 3000 (but not slipping, just won't lock up).
I've seen this a lot before we fixed the cooler pipe, first time since then. I had to mess about and in the end kicking down caused it to enter lock up after accelerator was released.

Do these D2 boxes have a governor on them? I've always suspected it's this sticking and not letting enough pressure in, moving through revs etc means that it gets a work out and frees up.

AFAIK only the non electronic ones have the governor, on these with ECU there is a output shaft speed sensor which can make you that trick i mean to give wrong readings which might not trigger a fault code, according to the fault code list it's not even covered by diagnostics, or even if it is i'm sure it's only for open/short circuit as IMO that EAT ECU is quite rudimentary in this area

Originally Posted by AUTOMATIC GEARBOX - ZF4HP22 - 24; 44-10 DESCRIPTION AND OPERATION

An output shaft speed sensor in the gearbox housing outputs a signal to the EAT ECU. The EAT ECU compares
output shaft speed with engine speed to determine the engaged gear, and output shaft speed with vehicle speed to
confirm the range selected on the transfer box.

Maybe I am dumb, but I cannot work out anything from the graphs.

One thing to remember is that the transmission will not lock until the engine temp is AFAIK at least 76C, so the early part of your trace is not relevant to checking lockup. It will not lock in 3rd or 4th so when you start along an expressway it will rev up to 2800RPM depending on the hill.

My trans will lock in 3rd at 70Kmh with any throttle ( and stay locked down to 60Kmh) and I am pretty sure will lock at a lower speed>60KMH on trailing throttle.
The trans will lock in 4th at >80KMh and stay locked down to 70KMh on light(ish) throttle.

It sounds to me that your first change was locking in 3rd then unlocking as you went under 60Kmh to stop at lights.

IMHO to check operation you need to get a level stretch and check locking by accelerating uninterrupted up through 80KMH and note locking in 3 then to unlocked 4 then to locked 4. The engine must be thoroughly warm .

I must say it does seem strange at first experience if you accelerate hard from a standstill as the trans will go 1-2-3 unlocked , 3 locked at 70+ ( revs down) , 4 unlocked until 80+ ( with revs rise from 3 locked ) then 4 locked.
It takes a few seconds for the trans to lock after each change .
Regards Philip A

The only thing I can see is a engine speed rise in the very first part of both traces. But as it occurs early it is consistent with the engine not yet up to temperature. Agree with Phil.

Originally Posted by PhilipA

Maybe I am dumb, but I cannot work out anything from the graphs.

One thing to remember is that the transmission will not lock until the engine temp is AFAIK at least 76C, so the early part of your trace is not relevant to checking lockup. It will not lock in 3rd or 4th so when you start along an expressway it will rev up to 2800RPM depending on the hill.

My trans will lock in 3rd at 70Kmh with any throttle ( and stay locked down to 60Kmh) and I am pretty sure will lock at a lower speed>60KMH on trailing throttle.
The trans will lock in 4th at >80KMh and stay locked down to 70KMh on light(ish) throttle.

It sounds to me that your first change was locking in 3rd then unlocking as you went under 60Kmh to stop at lights.

IMHO to check operation you need to get a level stretch and check locking by accelerating uninterrupted up through 80KMH and note locking in 3 then to unlocked 4 then to locked 4. The engine must be thoroughly warm .

I must say it does seem strange at first experience if you accelerate hard from a standstill as the trans will go 1-2-3 unlocked , 3 locked at 70+ ( revs down) , 4 unlocked until 80+ ( with revs rise from 3 locked ) then 4 locked.
It takes a few seconds for the trans to lock after each change .
Regards Philip A

I beg to differ but if you pull away from standstill in "Drive" the trans goes 1-2-3-4 unlocked until 80+ then locked. It only locks in third when third is selected rather than Drive.

Originally Posted by Pippin

I beg to differ but if you pull away from standstill in "Drive" the trans goes 1-2-3-4 unlocked until 80+ then locked. It only locks in third when third is selected rather than Drive.

Agreed , while this is the normal operation , there is a modification that can be done with the separator plate in the valve body to make it happen as PhilipA describes , 99.9% of auto d2's run as Pippin describes

I beg to differ but if you pull away from standstill in "Drive" the trans goes 1-2-3-4 unlocked until 80+ then locked.

You are probably correct as I usually drive around in 3 when towing at under 80Kmh to lock the trans, as the revs are usually lower in 3 locked than D unlocked and of course the trans will run cooler.

It may be that I have entered expressways in 3 then changed to 4 at under 80Kmh thus causing the up down rev situation.

Regards Philip A