okay so i tried to take this project on myself and now im realizing its not at all what i thought it was. s type started misfiring (i think) a month ago. took it to a shop and got an error cylinder 4 misfire. i assumed plugs since i couldnt find records of them being replaced and the previous owner had alllll the service records... idont think he ever even poped the hood himself. anyway pulled the coil and found a little oil pooled up cleaned it out and pulled plug it was an ngk iridium also coils 135and 7 have been replaced. when i put the new plug in four and fired it up check engine was gone and it was running the best ive heard minus the tensioner tick. happy with the work and with it getting late i decided not to mess with anything and put it back together with only on new spark plug... why fix what aint broke ya know. low and behold i get it together and the misfire is back. i tore it down and started testing i tried switching coil 3 and 4 misfire was still there. i unpluged 4 and it got alot worse, unplugged 3 and it was more mild but consistent. this lead me to belive the coil was going out. i grabbed a new coil from autozone and installed and the misfire is still there but def not as bad. now im wondering if its the gas at this point because i put mid grade in 2 days ago in thinking that it would explode easier. im lost someone save me ill take a video of the car running tomorrow and everything i described if it will help. Thanks in advance

 

Car details? See my sig:

 

sorry 2001 S type 4.0l with 107000miles

 

Are you sure you know which cylinder is in which position?
Also, are you sure you bought the proper coil?
If you have the wrong gas, you need the right kind. I think you call it Premium over there. You can expect bad running and possible engine damage with the wrong gas.

 

i had the wrong cylinder turns out it was 4 but the previous mechanic that replaced that coil labeled it 1. when i pulled the coil the "spring" came out and stayed on the plug....would the coil work if i put the metal back in? im not too woried about it i already bought the new one and not really looking forward to getting that cover off... it was practically impossible to get the back bolts out.

 

The layout of the cylinders is in this PDF https://www.jaguarforums.com/forum/a...achmentid=2914

My engine & coils are different enough that I don't know the rest.