so i was driving along on day about 80 mph. Then my vehicle started making a missing sound which i thought was probably from the fact that i jsut got gas in a tiny town that looks like no one ever buys gas in. my engine light came on. i took my code scanner and read it, misfire cylinder 8 is what it showed. i cleared the code and it came back on later. i thought that it was still maybe from the gas so i put the seafoam in the tank, heat for any moister and fuel injector cleaner, then toped it off with 93 from shell. i normaly run 89 in it. my vehicle has 89000 miles. and iv never had any problems out of it. LR put new champion plugs in it at 65000 miles. the plug leads as far as i know are the originals. i bought it when it had 50000 miles. if i clear the code and drive my vehicle normal the code never comes back. if i go down the interstate and get over 80 the code comes back and it reads the same thing every time. i swaped plug 8 with a different cylinder and still got a cylinder 8 misfire. then i went to auto zone and bought some plug wires and swaped out on clyinder 8 and still got the misfire. so i put the original back on. so my vehicle drives fine if i drive it normal and dont speed. under load my vehicle makes a gargaling sound. but never shoots a code. iv checked the freeze data every time the code has shot and its always about 3000 rpm and 40 - 50 % load on the engine. any ideas. i was thinking maybe i have a bad coil.

 

also i dont have any power. i can drive, but like a granny. if i were to have to step on it and get out of the way. id be screwed

 

I think you need a basic tune up. New Magnecore wires and all new plugs. From 50k to 89k you are due. Those plugs and wires have gone the extra mile in our hot V8 engines.
Choose from Bosch +4 or NGK Iridium. Or the Champion copper plugs if you are on a budget. This is a basic place to start. Also order a plenum gasket for your upper intake manifold. Its steel you will need to replace it once removed to change out your wires. Some folks claim you can change your wires without removing the coils, but I like to sleep well at night and feel a solid click on the coil pack. Replace one wire at a time and you will be fine. Also use dielectric(vasoline) grease on the wires and antisieze on the spark plugs. This should cure your problems and or give you good base to start.

 

thanks, ill let you know what i come up with

 

you need to start using preimum gas ALL of the time. its REQUIRED for your truck to run properly

 

As mentioned good gas only or you'llcarbon up the engine. Then install some 8 mm plug wires and do an induction cleaning along with a can of B&G's 44K in the gas to cut the carbon build up.

 

the guys at LR told me 89 was fine to run, iv ran that since iv had it. this is the only problem iv had. how do you do an induction cleaning ?

 

they said that my vehicle would just change the timing a bit to compensate the lower grade fuel. also, im looking on roverparts.com to get plug wires and the plenum gasket. is there another name for the plenum gasket ?

 

get the plugs from amazon the wires from apexperformance and the gasket comes in the HG kit from AB. and you need to start using premium fuel. what LR dealer told you to use 89?

 

brentwood, tn dealer... should i go with 7 or 8mm whats the advantage of either