Truck was running poorly and SES light came on. Changed code indicated MAF and bank 1 upstream O2 yesterday. Test drive was beyond awesome, really can’t remember the last time the truck ran so well. Throttle response was much improved, felt like it pulled a little hardener and ran much better at idle.

Fast forward 24 hours, drove it to a friends house 4 miles away and a 100 yards from the driveway I noticed it was running poorly and boom, flashing service light. Got to the driveway and it was barely running. I checked the codes and get (misfire on 4 and 7) p1300, p0304 and p0307. Check for sparks and it’s there. Checked all plug wires for connection at the plug and the coil restart with no improvement. Had a spare CPS laying around, swapped it in and no change. I unplugged the MAF and restarted and noticed it ran better but still terrible.

Plugs are new and appropriate, wires are 8mm installed late 2019 along with a new coil pack. Coils and wires from Lucky8.

remember this thing was running like it never had before 24 hours earlier.


Anyone have some first hand experience with a solution?

 

Didn't fill up in this 24hr time period did ya? I had one of my LR's run like total dog **** and it was having multiple misfire faults, and the CEL was flashing. Never had seen that on that D2 and it was running fine before. I remembered I had just filled up, got some of the fuel out and let it sit. Yep sure enough more water than fuel.....

 

I put gas in it a week before but had only driven it back to the house. About 1.5 miles.

 

Ok just an idea

 

I think I am reading your post correctly but just to make sure. You had one with the same symptoms but it was the first time with that particular Discovery. Have you encountered multiple misfires and flashing SES on any other Discovery?

 

Nope that was the only time I've had a perfectly running D2 with zero history of random misfires or faults act up. Checked the fuel and bingo that was my issue. I later went back to that gas station & several people had their vehicles completely die & not even restart... So technically I was lucky to just have the misfires and flashing CEL. After swapping out the fuel and a fuel system cleaner tossed in the tank she has never done that again.

 

i believe cylinder 4 and 7 share the same coil.

if so, could be a failing coil pack.


here's a link. to a related post.

 

Just pulled 3 spark plugs. They have less than 15 miles on them. The one pictured isn’t even from a cylinder I was getting a misfire code from. Bosch Double Platinum. Did I not get the memo? Do we not use these?

 

That style Bosch plug should work fine. It's the older design Bosch used to make with the tip of the plug was flush with the insulator = plugs fouled very easy. Could be the wrong temp range? I personally stick with NGK, Denso, or heck even autolite's in a D2.

 

Gotcha. But again these are brand new, all this build up from less than 15 miles and really only less than 4 with the misfires?