Hi everyone, I've never posted on this site before, though I'm always on here looking for way to fix my car. I'm hoping I could get some help to figure out why my car is running so rich. I have an 03 discovery that I love but its having some major issues. I believe its running very rich, horrible gas milage, quite rough at idle, and always has a heavy smell of fuel or unburnt fuel, and puffs of gray smoke when I hit the gas pedal hard. I've also noticed a ticking sound when driving at slower speeds and recently it has started stalling at stop lights or when I put the car into reverse. I believe It has an exhaust leak but now I'm not so sure. Could it be bad o2 sensors? A vacuum leak?

As for the misfiring, my check engine light have flashed at me probably over 15-20 times the other day on my way home, assuming its misfiring every time it flashed. Then I used a code scanner at my work and it showed misfires in cylinders 2, 8, 4, and 6 as well as a random/ multiple cylinder misfires code. I'm choosing not to drive it at the moment.

I know that's a lot of information but I would really love some answers or any help and wisdom you guys might have. Keep in mind I'm only 21 and this is my first car, so I don't exactly have a ton of experience, but I am mechanically inclined and am willing to do whatever it is I can to get my disco running smooth again.


I had to share a photo because I know you guys will apricate a rover!

 

Great pic! Definitely looks to be worth fixing. But your issue could be almost anything at this point. Head gasket, bad coil, sliding cylinder sleeve, leaking injectors, short anywhere, O2 sensors...the list goes on. If you are new to working on vehicles, I would suggest finding a local LR mechanic to diagnose......and do not drive it until fixed.....

 

Until you wrote that the misfires are all on Bank 2 I was thinking vacuum leak, but the symptoms point to a bad upstream O2 sensor on the right hand side (passenger side in the U.S.).

The fact that all the misfires are on one side is what points to the O2 sensor. The O2 sensor is the only engine management component shared by all the cylinders on just one bank.

Some have argued here that a bad O2 sensor will not cause misfires, but I have personally seen it happen.

 

I have an 03 Discovery and I had the same problems as you. It happened out of nowhere. Turns out the coil packs just gave out. Once I replaced the packs, wires, and plugs the issue went away and has not come back since.

 

My 04 was similar. Replaced the spark plugs and it improved. Did the Best4x4 PCV mod and found the oil separator in my 04 was completely clogged and causing back pressure in the valve covers and causing leaks and misfires. So, 1) new plugs. 2) Best4x4 PCV mod for the 03-04 model which includes hollowing out the oil seperator in the passenger side valve cover and changing the plastic nipple to a PCV valve on the intake side of the air tube. See https://landroverforums.com/forum/di...T7FM4x3a66Qi8Y

Also documented on Facebook at facebook.com/groups/746322152082758/permalink/5595799600468298

 

Welcome to the forum and Land Rover ownership.