Started to run on five cylinders last week and wouldnt go back to six. Checked coil packs and no 2 was doing nothing i.e when car was running taking it off didnt adjust revs. Went over to Z Tech and was getting fuel and spark but compression test showed to be very low (130 if i remember correctly) and on no 1 was even lower, i think 100. Anyway back home i came and suddenly it started running on 6 again and felt like nothing was wrong. This morning i have taken her out and refilled with Tesco 99ron, on way home she dropped back to five then after a few mins back up to 6 again. Could this be anything silly or is it time to rebuild the engine?

130 (or 100) is'nt low enough to prevent it running on that cylinder(but thats not a good sign, and would indicate rebuild time due)

 

It will be a bad connction. Either coilpacks, injector connectors, PTU or ignition/injector harness(more than likely) in between. Try wiggling all the wires to see if it makes a difference.

 

Also clean the connectors on coilpacks, injectors and PTU

All wires have been well and truly wiggled and cleaned! Because it is intermitent that is what i think it must be but it is going to be difficult to locate which one it is. Last night when it started to run on 6 again i rechecked the coil pack on no2 and it did make a difference to the revs which it hadnt done before. Not mechanically minded seeing as Ryan had to point out to me what a coil pack was in the first place! but seeing as this had changed do you think it is pointing towards a problem around the no2 coil pack?

I went through this recently, swapped coil packs over e.t.c. turned out it was the injector connector, as Legrath suggested, though it didnt come back to life with just a wiggle, it took a bit of cleaning to.

it could be an internal break in the PTU, usually its on the main feed/earth & the thing packs up altogether. it could be on the output to just 1 coil pack tho. might be worth trying to get hold of one to borrow for a while to test it.

had exactally the same thing my self last week the problem was with the conectors on the injectors just jiggle thm about one by one ther are only six you will sharp find out wich one it is