Auto box change up to 4th fault

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D

dirtyrov

New Member
Posts
58
Location
Euxton (Lancashire)
My 4.0se has developed a fault after i had a miss fire while running on gas. The problem started after my gas has a miss fire under hard accelleration causing the box to shift up and down irraticly.

Now the box has an issue when it changes to 4th. On the way up the gears when driving in D, the box changes lovely and smooth but before changing to 4th it changes down to 2nd from 3rd before changing straight back to 3rd and then changing up to 4th a few seconds later. BUT.... If i am plodding allong in 4th and need to accelerate a little and it changes down to 3rd it does so fine. And when it changes back up to 4th it does with out changing down to 2nd. But if i make it kick down from 4th to 2nd the fault is back when it tries to change to 4th again.

Ecu fault?? Any ideas?
 
have a look at the thread on auto gearbox flaring,sounds like that might be what its doing :)

Should also mention that the autobox is in 4th gear long before the torque converter locks up and gives the"final gearchange" at around 50mph.

Worth trying a gearbox oil and filter change and a bottle of lucas transmission fix.It has worked wonders for many on here .
 
Last edited:
thanks for the reply. i did an oil change a few months back. i have ordered a second hand ecu to try. if this doesn't work i will do another oil and filter change. bed advice on what oil i should use?
 
dirtyrov said:
thanks for the reply. i did an oil change a few months back. i have ordered a second hand ecu to try. if this doesn't work i will do another oil and filter change. bed advice on what oil i should use?
Click to expand...

When you did the change did you change the filter? Sounds like you have a sticky valve block due to **** being released by new fluid. Change filter/fluid and stick some Lucas in it.
 
roughly 100 miles before i got the gas fault which caused this fault. i think i may go down the oil change route this weekend with some lucas in there for good measure.
 
I still have my fault but if i fit the spare ecu i have the fault moves down a set of gears. but you can change between 1,2 and 3 manualy fine. but as soon as you click it into d from 3 it selects 2nd then 3rd straight away before going up to 4th. but if you leave it in d it changes 1st to 2nd fine. but from 2nd it selects 1st for a second or two before going back into 2nd then up to 3rd. 3rd to 4th changes fine. Where with the original ecu the fault is in the 3rd to 4th gear change.
Bloody wierd. I am sure it has to be a sensor, and each ecu is interpreting the signals differnetly or something.
What sensors are there though that the box uses. throttle position? rpm? speed?

I also think my changes are a bit clunky sometimes. other times i don't feel them but some times i notice the gear changes.
 
dirtyrov said:
I still have my fault but if i fit the spare ecu i have the fault moves down a set of gears. but you can change between 1,2 and 3 manualy fine. but as soon as you click it into d from 3 it selects 2nd then 3rd straight away before going up to 4th. but if you leave it in d it changes 1st to 2nd fine. but from 2nd it selects 1st for a second or two before going back into 2nd then up to 3rd. 3rd to 4th changes fine. Where with the original ecu the fault is in the 3rd to 4th gear change.
Bloody wierd. I am sure it has to be a sensor, and each ecu is interpreting the signals differnetly or something.
What sensors are there though that the box uses. throttle position? rpm? speed?

I also think my changes are a bit clunky sometimes. other times i don't feel them but some times i notice the gear changes.
Click to expand...

Stick on diagnostics if nothing comes up it's mechanical.
 
Thats not always the case though untill something goes down completly it doesn't always show up .How would a mechanical fault change with a different ecu? its going for air bag light resetting tomorrow so i will get any codes read too.
 
dirtyrov said:
Thats not always the case though untill something goes down completly it doesn't always show up .How would a mechanical fault change with a different ecu? its going for air bag light resetting tomorrow so i will get any codes read too.
Click to expand...

Equally, why would an ECU change cause the fault to change if it's a sensor problem? I suppose your battery is good and the alternator is charging properly?
 
Electronics are black magic! a mechanical problem doesn't change, once its there its there. my battery and alternator all work fine. voltages are as they should be. Its getting to the point where its going for a drive off a cliff never to be seen again! And get me a truck with a real gearbox!
 
dirtyrov said:
Electronics are black magic! a mechanical problem doesn't change, once its there its there. my battery and alternator all work fine. voltages are as they should be. Its getting to the point where its going for a drive off a cliff never to be seen again! And get me a truck with a real gearbox!
Click to expand...

Regretably mechanical problems in auto boxes can come and go. Sticky valves are not that uncommon. You should have 14.2volts with the engine at 2k rpm. Gearbox faults linked to low battery/alternator voltage are also common.
If changing the ECU changed the problem, was it the correct ECU? There are at least 3 different versions.
Check the connector to the autobox for corrosion and the loom for chaffing.
 
Depending on which ecu i use the fault is different but doesn't change while that ecu is fitted. my spare ecu isn't the correct part number but is for a 4.0. I will see if any fault codes show up tomorrow but with me swapping ecu's about there will prob be a list as long as my arm. I may go for an oil change but after that i think i will just invest in a td5 disco. I already have to much money in the rangy.
 
dirtyrov said:
Depending on which ecu i use the fault is different but doesn't change while that ecu is fitted. my spare ecu isn't the correct part number but is for a 4.0. I will see if any fault codes show up tomorrow but with me swapping ecu's about there will prob be a list as long as my arm. I may go for an oil change but after that i think i will just invest in a td5 disco. I already have to much money in the rangy.
Click to expand...


Bit pointless trying the wrong ECU
 
beg to differ!! if the fault was mechanical it would still be there in the same place!! A bit like having a dodgy spark plug and changing the coil. the fault wouldn't move!
 
dirtyrov said:
beg to differ!! if the fault was mechanical it would still be there in the same place!! A bit like having a dodgy spark plug and changing the coil. the fault wouldn't move!
Click to expand...

If it's sticky valves and the ECU sequencing is different who knows?
The auto box on mine is iffy, the fault can be masked with snake oil and it comes and goes, no clutch slip so it's most likely sticking valves. It's still mechanical.
 
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