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Discussion Starter #1
Hi guys 1996 4.6HSE, I have had the problem from beginning of ownership,

Issues

-SPORT button does not work, it only works when in low range
-when I press the SPORT button straight after I turn the ignition on the button works ans SPORT is displayed on the dash however this disappears straight afterwards and the SPORT button indicator light goes out
-Gear box on very light acceleration revs up to about 4000rpm then jumps into second no clunks or bangs just a very harsh shift
-On moderate to heavy acceleration gear changes are smooth all work fine until 3rd gear, the gearbox works its way up to 1, 2 and then 3 all very smooth until 3 when it changes into 3rd it automatically changes into 4th and then goes into back into 3rd and carries on smoothly into 4th
-On hard acceleration all is smooth
-On medium acceleration all is fine except 2nd changes quite roughly

When gear changes happen there are no clunks or bangs.

What I have done:

-Changed the gear selector indicator surround
-Changed fluid and filter 8000km ago the filter had quite a lot of sludge in it but no metal, oil is currently slightly discoloured at the moment but am planning another filter and oil change in 2000km
-Checked the fluid level on two consecutive days from cold and at the correct ambient temp the levels are bang on and 100%
-Changed the gearbox ECU with a working ECU, I did this briefly to test the ECU but nothing changed
-All fuses are ok and there are no warnings on the dash
-Plugged in Autologic and there were no faults stored in the gearbox ECU or engine ECU
 

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1995-2002 Range Rover P38A
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As mentioned when we spoke I would try a good MAF sensor (Air flow metre) gearbox ecu gets a signal from it to determine gear change.

Your problem could even be as simple as removing the round multi pin connector on the gearbox and spraying it with contact cleaner, may or may not be related
 

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Discussion Starter #3
Sorry viper I forgot to mention I tried your sudjestion about the MAF and have also cleaned all the connection onto the box with contact cleaner.
 

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Not familiar with the ZF, but have had experiences with Mercedes Transmissions and wondered if it could be a vacuum leak if the Transmission uses vacuum as a signal at all.
If not then check/swap the Throttle Position Sensor if it has one...
 

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Well, first i am not sure if this transmission has any kind of vacuum input.. maybe someone can say for sure?
I just know that on my sons mercedes we had some really odd shift conditions and it turned out to be a perished rubber pipe. Most auto transmissions rely on a vacuum source or vacuum sensor to tell it what the engine load is in addition to a TPS.
I did a litte research and found this... but strangely it says that the 4.6 is not fitted with this transmission, but the RR.net site says it is..
http://en.wikipedia.org/wiki/ZF_4HP22_transmission
If this is the correct transmission I suggest you sniff around the BMW forums and maybe post the symptoms there.. sheer volume will dictate taht someone will have seen this issue before!
 

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KeyRange said:
Ok, cool.
Then it still must have a sensor to input the vacuum that the engine is producing.
The gearbox ECU talks to the engine ECU.
 

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1995-2002 Range Rover P38A
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KeyRange said:
Ok, cool.
Then it still must have a sensor to input the vacuum that the engine is producing.
The engine ecu sends info to the gearbox on how much power is being output, when the box wants to change the gearbox ecu sends a ignition retard request to allow for a smooth gear change.

Jeremy, Im thinking there's a silly wire issue here, gearbox wiring harness prehaps.. I mention this as it runs tight behind the left seat mounting, maybe a wire has shaffed through.
You;ll have to remove seat and some lots off other trim etc to check it out.

I did mine but removed both seats as some numb nut so called LR indy RRover specialist screwed up the low-Hi range system....one of the many reasons why I bought this ex lemon which now proudly outshines many other P38s with lesser mileage.
 

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Discussion Starter #14
I am now positive it is an electronic problem, however shouldn't there be a fault stored in the ECU as previously mentioned I had it plugged in and there were no faults.
 

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1995-2002 Range Rover P38A
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I've just finished reading up on the auto box ECU workings, by all accounts your problem is pointing to two areas.

1: Auto box ECU
2: Bad electrical conections.

Thoughts:

1: As you are not able to select sport Im suspecting Auto box ECU as it controls this function.

2: Under the coolant reservoir there are two connectors and the yoften get slight corrosion,
Lifting up the res and disconnecting aswell as removing these two plugs will no doutb reveal some sort of issue as they send and recieve signals from the auto box ECU amongst other uses.....

You said you tried another ECU, not really the best of ideas as RAVE mentions if ECU is swopped out it must be recalibrated, these ECUs are adaptive and vary from each other due to different wearing rates from box to box..
 

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Discussion Starter #16
Viper, gave the connections a good clean yesterday with some contact cleaner the smaller one looked fine but the larger one had a slight amount of corrosion in it. There is a third connector there a white one with two wires running out of it that is not connected.After giving the connectors a clean there was still no change in the trans

When I swapped the ecu over for another one I only ran the car up and down the road about 2km max but again there was no change
 
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