Land Rover Repair: 99 Disco II misfires, land rover discovery 2, land rover discovery

Question
Land Rover Discovery 2. 4.0 petrol V8.  V reg (99).  
Popping sound through the exhaust.  misfires (kangaroos) for 15 seconds after inital cold start up.  fine when warm.  reset ECU.  changed spark plugs from original Champin to NGK to Bosch 4 pin.  Changed Lambda on both CATs.  Slight lack of power.  Diagnostic equipment says lean mixture for each bank.  Any ideas?

Answer
Hi Melissa,

could be a fuel filter or fuel pump fault or even a vacuum leak.  It's also possible you have fouled fuel injectors.  You could test to see if you have low cylinder compression troubles too.

May be the start of the the sticking exhaust valve problem common to Disco II's (hope not).  Lack of power and misfires are symptoms of this...especially on hot and humid days, and can be really noted while ascending large uphills.  Only fix for this is a valve job.

Let's hope it's fuel related and simple to fix.

Best of luck,

JohnMc