The ignition cables are shielded and wont interfere with each other. Arching and some sort are caused by damaged cable or the spark plug ceramic shield itself is cracked. Cable length does not really matter, the ignition travels in lightning speed and wont notice the difference.

 

I can't think of any reason you shouldn't be able to do a compression check with the manifold off and all the plugs removed. Than just jump the starter to get is spinning.

 

Alright, well I checked the compression on cylinders 8 and 6. (Aside: my tool collection has grown immensely from this project). Both registered about 120 after a few bumps.

So I'm not finding indications of coolant in the cylinder, and it appears to hold compression (??) which would make the HG job a success? About the only thing I haven't replaced are the O2 sensors. With pretty much a single cylinder misfire I've been avoiding that replacement.

 

Ok, good luck again. Check other recent post had 1 cylinder misfire and saw that the new spark plug was damaged and arching. He forund out when he run the car in total darkness and saw that electrical leak.

 

What a bummer, this thing is kicking your A$$.

I would try new wires and plugs all around just in case, while the manifold is off.

 

I have new wires and coil packs, and I'm on my 3rd iteration of plugs for some of the cylinders.

I've buttoned it back up for now. I pulled the plugs on #6 and #8 to do a compression test and after re-installing the plug in #6 now that is misfiring. Along with a random misfire. I'm betting I'm not seating these new wires right. I'm going to wait until this evening to check for any arcing and may re-apply some connectors. It was a really rough idle and hesitation when accelerating, which is probably the worse I've seen so far.

I'm not going to let this thing beat me.

 

I started it up tonight in the dark and I was seeing some arcs from the newly misfiring #6 cylinder. I guess I'll replace that plug tomorrow. None of the other cylinders appeared to be showing arcs.

I'll post an update after replacing the plug on #6. I'm still at a loss on #8 though....

 

Alright, so I had been using the wrong socket for plugs the whole time and have broken like 3 of them. I got a spark plug socket, some dielectric grease, and a new plug for #6. That cleared the rough idle and hesitation.

I cleared the codes and let it idle for about 15 minutes. It was running quiet and smooth so I decided to take it for a test drive. A mile down to the gas station, after stopping and getting back in the SES light came back. When I got back to the house I checked the codes.

Now my iCarSoft has 2 diagnose modes. 1 for ODB2 and 1 for Jaguar/LandRover. The ODB2 is showing 2 codes, the P0308 and a pending P0130. Now the LandRover DTCs in the other section reflect the same errors but also a "misfire on multiple cylinders". So the ODB2 is only showing a #8 misfire but the DTCs list a generic multiple.

I'm starting to think I'm chasing ghosts here. The P0130 is for Bank 1, but I've only got a single misfire still in #8 which is the other bank. I'm just wondering if the conflicting info in the vehicle DTCs and the ODB2 codes could indicate that it is actually multiple cylinders which could be caused by the O2 sensors? It's about the only thing I haven't done yet.

 

You probally got coolant on the o2 sensors when you redid the heads and screwed up the o2 sensors. Get you a set of walker ones from rock auto. Just a little over $100 with shipping from rock auto. I went that route BC too many people were having issues with Bosch ones out of the box being bad. It fixed my misfire issues after mine

 

While I'm waiting on my O2 sensors to arrive, I had 2 questions.

A few non-Rover people I talked to were confused as to why O2 sensors could cause misfires. They could see lean/rich codes but not necessarily misfire codes. Does anyone have the logic behind why the O2 sensors seem to be the culprit for some Rovers?

Also, I had my brother take a look at the engine and he thought he heard air on the passenger side of the engine and thought I may have a vacuum leak. We sprayed more carb cleaner around and the only real difference we noticed was spraying down into the gaps of the intake manifold. The hose connections seemed fine. So I was thinking possibly the plenum gasket? I put a new one on with the HG job, but I've removed the upper manifold at least 3 or 4 times since then. Should there be any RTV type sealant with the plenum gasket?