1996 v8 auto discovery

Please Help 1996 Land Rover Discovery 4.0 v8 auto. It runs fine until it warms up, then when it gets above 40 miles per hour it sometimes will lose power for about 3 seconds and then resume normal power for a while before it loses power again, it will repeat this cycle until you get below

40 miles per hour or after the engine cools down again. It passed georgia emissions
Reply to
d mackay
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Are you sure this is speed related and not RPM related ?

Are you sure this is a 4.0 and not a 3.9 ?

In the UK the 4.0 version wasn't introduced until later on, which is why I ask. The 4.0 and 3.9 are actually the same displacement (3947) but the

4.0 designation was a marketing tool to mark the change to distributorless ignition and a more complex injection system. The US normally get these things first but that does seem very early.

If it's a 4.0 it could well be one of the coil packs breaking down. The

4.0 doesn't have a distributor but uses 4 coil packs at the back of the plenum chamber. These can break down as they get hot and this is more noticeable at higher RPM.

If it's a 3.9, see if it does it in a particular RPM range. 2900-3500 RPM seems to be a favourite speed for the distributor to cause problems if the shaft is worn as the shaft starts to oscillate and screws up the air gap. A faulty alternator can also cause a similar effect if it's dropped a phase.

Next time it does it, floor the accelerator and get the gearbox to kick down or manually select 3rd or 2nd, see if the engine runs OK at higher revs.

If it is temperature related you could try the "cure all" of replacing the coolant temperature sensor for the ECU (not the one for your temperature gauge). These are cheap to replace and play a significant role in the injection system.

HTH

Dave W.

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Reply to
Dave White

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