Land Rover Repair: defender 94 chugging, vacuum leaks, vacuum leak

Question
just took my car to import service and after 4 hours can't diagnose why defender is chugging intermitently while driving. idles fine, defender is backfiring changed the flow sensor no change, changed gas filter, distr cap and plug and wires. no change. any info?

Answer
Hi Ladden,

misfires are a result of the following:

fuel injectors fouled;
coil failure;
cracked distributor cap or internal points worn;
spark plug wires old and lacking insulation - arcing;
old spark plugs or poorly gapped;
vacuum leaks;
fuel restricted due to blockages, fouled filter, vacuum buildup in tank or line;
fuel pump failures.

Since you've had some parts replaced, consider testing the fuel and cylinder pressures.  

Mist water over the wires in the dark part of your garage one evening...any sparks seen?

An old trick to find vacuum leaks is to use a 'smoker' that releases a plume of smoke from a canister.  If a vacuum leak is present, you'll see the smoke drawn in.  I guess you could use an incense stick...to find the leak of course!

Best of luck,

JohnMc