New to this site. Great reading and feed back. Kudos to all!

My dilemma: I have a 99'Disc 2 with 103000 mi. Serviced as scheduled. Problem started after smelling gaseous odor while cruising on the freeway/highway. I pulled over and noticed the car running rough. Days later, I scanned the computer and noticed codes P0134 and P1590 (another issue). I ordered and replaced 4 o2 sensors from Atlantic British - Cleared codes and drove a bit.. still running rough. Scanned again and got P0308. Ordered and replace with 8mm magnecor wires. Cleared codes and drove again... Scanned and still getting P0308. What is my next step? Someone mentioned compression test. Replace coils? Any thoughts?

 

P0308 is a misfire on cylinder 8. Check that wire connection and then check the plug for spark. You did not mention new plugs so if that is the case then replace the plugs. If all those check out then check the #8 fuel injector.

 

Replace all of your spark plugs.
Clear the codes and see if any come back.

 

P.S. The spark plugs were changed out as well....Bosch Platinum +
Continues to produce P0308 and P0300. Doubled check plug wire layout... Thanks lipadJ46 for the diagram. Next step... compression test to r/o valve job vs. coil replacement. Will f/u with post.

 

Are you still smelling gas, may have a bad injector seal or injector, should show up as a 208 fault code but not always.
Pull the plug and smell it, does it smell real gasey?

 

Thanks for responding DM. The gas smell is gone. The plug looks good. I had a mobile mechanic do a compression test and all came back w/o any issues. I am not getting the 208 fault but still continue to get P0308.

I did notice hearing a humming noise around the firewall after the engine was shut down. Bad injector or time for new coils? If the latter, can the coil with #8 cylinder be replaced only?

 

One coil will spark 2 cylinders.
So the #8 coil will also spark the #5 cylinder.

 

So two it is.... Thanks Spike!

 

Well you could have a bad head gasket my disco is getting cyl 1 missfire becouse of coolant on cyl head!? But in your case I dont think so becouse you are smelling gass!

 

I am looking through this forum for answers on this and similar threads, and there doesn't seem to be a resolution. I need help! I have a 2002 Discovery. The truck was purchased not running, and then the entire engine was rebuilt by family with tons of experience with cars in general. This was 4,000 miles ago, now at 107,000, so new head gasket, new spark plugs and wires.
Drove the car 4,000 miles, including 1500 across the country unfortunately away from my family who built it, and it ran beautifully. Then it started to get codes of P0171, P0174, P1171 and P1174. Then, truck ran okay. Then, it started to miss in a small way, like a little jump. The codes then changed and included misfires, often P0308 (most always), plus P0305, P0300, the damage to cat one (P1300 I think, but that's from memory). Also, the ABS codes, P1590, with the three amigos lights. As it would run, the truck's performance deteriorated.

I changed the spark plugs, and that didn't help.

So... I took it to an indie shop with good ratings on Yelp. I told them this history, and they told me (in three separate phone calls throughout the day) that it was the lower intake manifold gasket causing a vacuum leak. I'm not certain if that was true. Two days later, the truck ran worse than ever, throwing P0308, sometimes, P0300 and P1590. I took it in the next day and got it back tonight. Their recommendation and work: change out of the coild packs, and I had them do both. They claimed this time there was no spark going to number 8.

Driving home, it's starting to do the beginnings of that same thing, jumpy misses, although no SES light ... yet, but I know it's coming. As I pulled in to the driveway, I had the ABS light come on. Those lights come on as if there actually is a vacuum issue with the truck.

I'll see what happens tomorrow, but I'm betting it will turn into the same thing: P0308 and P1590.

Yes, I'm jumping the gun a bit because I don't have the codes yet, but this is frustrating. It's $1300 in, and the shop is throwing parts (very inside parts I must add) at the truck when it seems there is some mystery to the P0308 rough running code (all with new spark plugs, wires with only 4,000 miles, brand new coil packs and a supposedly verified not-leaking intake manifold gasket).

If anyone has resolved this issue, I'd love to hear how. Please!!