I have a series of P1000 codes. Any help diagnosing the cause is appreciated.
2000 Discovery II 155,000 miles
The codes are:
P1000 (75) Catalyst Damaging Misfire Multiple Cylinders
P1000 (66) Misfire Cylinder 4 with Cylinder Cutoff P1000 catalyst damaging misfire cylinder 4
P1000 (62) Emission relevant misfire multiple cylinders
P1000 (53)

Engine lugs or misfires when it comes under load (for example up a steep hill).
So far I only replaced spark plugs
Are these codes caused by faulty MAF sensor, O2 sensors, spark plug leads, and Ignition coil?
Thanks!

 

Causes: all of the above.

 

Agreed. Plugs, wires, coils, MAF and O2s are a solid place to start. I would do all of them at once and if nothing else you can rule them out as you move forward with troubleshooting.

 

Thanks for the feedback! An experienced mechanic, who has only some LR experience, told me it may be #4 cylinder exhaust valve sticking under load. Is this possible? (or probable!)

 

Most Rovers that have a misfire on 4 have a cracked block. You can tell that by looking for coolant in the cylinder... How did that plug look when you pulled it out?

Of course you have to rule out the other things... But sticking valve on 4 is less likely than wires or coil packs. O2 codes are a result of the misfire, not the cause.

 

I have no indications of a cracked block at #4 where my sleeve had pushed up. No coolant or steam cleaned piston. I have never heard that #4 was more susceptible to being cracked than any other location. What makes #4 more susceptible?

 

Thinner walls on the center four cylinders. Most all of the cracked blocks happen on 4,6,3 or 5.

 

Try a hard reset. Disconnect the battery, touch positive and negative cables together. Hold or clamp together for a while, 15-30 minutes maybe. Put it back together. No guarantees but it helped me after replacing some parts and still getting codes.

 

I got rid of the P1000 codes.
I changed spark plugs, plug wires, both ignition coils, and fuel injector for cylinder #4. Seems to have done the job.
The original codes were :
1000 (75) Catalyst Damaging Misfire Multiple Cylinders
P1000 (66) Misfire Cylinder 4 with Cylinder Cutoff P1000 catalyst damaging misfire cylinder 4
P1000 (62) Emission relevant misfire multiple cylinders
P1000 (53)

Right after solving that problem I got 2 more codes: p1000 (80) and P1417. I changed the solenoid for the secondary air injection. The solenoid was toast, hopefully all else is working.
I'm looking forward to 2 consecutive days driving with no codes and no SES light.

All hands were required to pump and capture smoke while tracing possible leaks in the secondary air injector.

 

What's the black cylinder between the air intake tube and the power steering reservoir? Looks sort of like an SAI pump but it's in the wrong place.