Mysterious running problems are back!

[Cro]

Ok so a while back I had a problem of the 172 running on 2 cylinders, I had changed the coil pack,HT leats, spark plugs and both llambdas. It was still present after they were changed but mysteriously they just went away and all was fine. Just yesterday the same problem seems to have come back, on the code reader im getting both llambdas, secondary ignition coil and multiple misfire. Having changed those so not so long ago... 3 thousand miles max... if even, so im stumped as to what it could be. Any thoughts??? The odd time i start up it will be fine then come back or be driving and it will jump into life for a bit!
Symptoms are as well as the above:
- no spark from number 2 & 3 on the coil pack
- injector 2 & 3 not firing

 

[ditz]

ecu by the sounds of it fella..
could also be a wiring fault.. but thinking about it it would need a fault in both the coil pack wiring and the injectors. as they are both triggered seperately by the ecu but its all calculated from the crank sensor input.

i suppose theres a backhanded chance it could be the cps but i highly doubt it

not sure if injectors and the coilpack use a common earth point i think they do and its taped up in the loom, be worth checking this.

other than that i'd say ecu.

 

[ditz]

check all engine earths aswell

 

[Cro]

Cheers ditz gives me something to check, dont say the ecu word cause that means £££

 

[ditz]

its always worth just unplugging the ecu aswell and look for corroded connections etc

 

[Cro]

unplugging from under the bonnet wont cause any other problems on reconnection again would it?

 

[ditz]

no just disconnect the battery and leave for a while first
i always make sure the key is out of the ign to.

 

[Cro]

where is the earth points in the engine bay, mainly the one for the coil pack and fuel injectors

 

[ditz]

well that ones taped up in the main section of loom that runs over the top of the gearbox..
the engine earths though theres one down by the starter motor bolted to the engine and another down in the passenger wheel arch goes from the box to the body

and then the one that goes from the battery to the body/loom

 

[Cro]

Well its fixed... touch wood. Ecu connection problems ditz so thanks for the idea. Taken apart, wd40'd and a couple of what i thought might be loose connections were re plugged and fired up right away! Hopefully all stays good