2001 Discovery II w/ 135K
Problem started with P1300, P0304, P0307
No spark on cylinders 4 & 7
I’ve replaced the wires, plugs, and coil packs.
Still getting P1300, P0304, P0307
What is the next step to diagnose the system?

 

how did you verify that you have no spark on cylinders 4 and 7.?

 

I used an inline tester. All other plugs test OK.

 

With new coils. plugs and wires, there isn't anything that can cut the spark. Are you sure you have no spark? If it were mine, I would do a compression test.

 

Could there be a failure on pin 7 of ECM Connector 5 (C0638) which fires cyl 4 & 7? How would I check that to rule it or out?

Compression checked out OK.

 

Also, the system is throwing the following codes:

P1300
P0304
P0307

Sometimes a P0300.

I'm stuck.

Is there a fusible link/relay?

 

check the ground point for the ecm....I helped a guy a while back with a similar problem and one of the rover techs on here recommended checking the ground. Never got back to us if it works or not, but if he never got back and said it didnt work, im gonna make the assumption it did.

 

Thank you. I'll take a look at that tomorrow.

 

Do 4&7 share a coil? Just thinkin out loud, maybe a bad connection, or no juice getting to the coil?

 

Yes, they do share the same coil. I need to somehow test the connection between the ECM and the coil. It could be the connection or the ECM. I don't know yet. And, I haven't a clue on how to test it yet.