Hello all.

Pretty new to me Discovery 2. I’m having a very frustrating time diagnosing a misfire. It’s running very poorly, flashing check engine under load. I’m starting to think it’s electrical related. I’ve replaced plugs(NGK), wires(Magnecore) and both coil packs(LR) as a tune up/preventive maintenance. I’ve also cleaned the MAF and tried unplugging it with no change. I’m 100% positive the spark plug wires are routed correctly. I’m positive it’s not the head gasket as I’m not loosing any coolant and there’s no mixing of oil/coolant vise versa. No overheating etc.
I’ve poured through this forum and others lots of people have experienced similar problems but have never posted the results. This is very frustrating.
The same codes that were popping up prior to the tune up persist: P0301, P1300, PO302, P0303, P0300, P0130 and P1884?.
Its getting progressively worse, almost un driveable.
The disco has a few other issues, likely unrelated but worth mentioning. A severe rear main seal oil leak and a battery draw.
Any thoughts? Thanks very much

 

When you replaced the coil packs, did you bolt the mounting bracket back onto the engine? It needs to be attached with all four bolts otherwise you'll get misfires.

 

Yes I did bolt it down in all 4 spaces

 

Low battery voltage will cause a lot of problems, as will vacuum leaks in the intake system. You also have an O2 sensor fault among those codes (P0130).
Also, triple-check your plug wiring just to be certain.

 

why is that?

not doubting you.

just curious.

 

The coils need to be properly grounded. A lot of people have found that they develop misfires if the coil mount bracket isn't fully bolted down. I remember reading that a few people have discovered that previous owners (or even indy mechanics) have left the coil brackets just floating around behind the engine because they can be a bit tricky to get to.

 

Today I quadruple checked my work. I also cleaned all the grounds. I unplugged the o2 sensors. Then the MAF. No difference. Still misfiring like crazy. Any more ideas?

 

Check if the 15A fuse F2 in the engine bay is blown.
I've read this too. When I installed new coil packs I made and added an extra 10AWG grounding cable from the coil pack bracket to the ground bolt on the firewall.

 

Did you check for vacuum leaks? Try carefully spraying starter fluid around and along every hose, pipe, lump, blob, and object under the hood to see if there are any engine surges that would indicate a breach of integrity.
While you're doing that, keep your eyes open for any broken or fragile wiring.

 

I had a couple issues with mine. First I'd say check that vaccum line that runs from the intake manifold over to the brake booster. Make sure its seated in there good. Also, the D2 is very finicky electrically. Check the battery connections. I've went over my terminals with the wire brush, but it's been about a year. I went and loosened my positive battery terminal and wiggled it around and then tightened it back up. Fixed all of my electrical codes and misfires. Give it a try.