QQ: coilpacks and misfire

[Robbie C]

Short version: Can a bad coilpack prevent the engine from starting/idling at all without helping it with the accelerator?

Long version:

OK so I've recently removed my SAI, N112 and N249 and replaced with resistors, fitted a catch tank and phenolic insulator gasket, while having my rocker cover, inlet mani and some other bits sent off to be sprayed.

I put it all back together yesterday and it was idling fine when I first started it. Went to go out last night and got 1/2 mile down the road before it started misfiring - classic sign of a coilpack I thought to myself.

Brought it back and it was still idling, just very roughly. So disconnected each injector connector one by one and found that cylinder 2 was my culprit.

So this morning I found a spare coilpack that I had been keeping in the boot and swapped it over but still no difference - however I have never tested this coilpack and it has been rolling around loosely in the boot for nearly a year so I can't say whether I'm swapping it for another bad one

I then ran VAG COM and found the following:

10 Faults Found:
18011 - Internal Control Module Failed Self-Test
P1603 - 35-10 - - - Intermittent
16684 - Random/Multiple Cylinder Misfire Detected
P0300 - 35-00 - -
16685 - Cylinder 1 Misfire Detected
P0301 - 35-00 - -
16686 - Cylinder 2 Misfire Detected
P0302 - 35-00 - -
16687 - Cylinder 3 Misfire Detected
P0303 - 35-00 - -
17645 - Fuel Injector for Cylinder 1 (N30): Open Circuit
P1237 - 35-10 - - - Intermittent
17646 - Fuel Injector for Cylinder 2 (N31): Open Circuit
P1238 - 35-10 - - - Intermittent
17647 - Fuel Injector for Cylinder 3 (N32): Open Circuit
P1239 - 35-10 - - - Intermittent
17648 - Fuel Injector for Cylinder 4 (N33): Open Circuit
P1240 - 35-10 - - - Intermittent
17658 - Fuel Level too Low
P1250 - 35-00 - -

Now I believe I can discount the injector open circuits for me disconnecting each one to find the cylinder that was misfiring? Leaving me with a misfire.

NB - There's a code for fuel level too low but I think this may be where it was on axel stands on the front for over a week. It has 1/8 tank but is on the light admitedly - however as I'm getting faults for misfires on individual cylinders then I think coils are more likely

My other feeling is that it may be an injector as these were also removed and re-seated when I took the inlet mani off to be sprayed and to remove the PCV valve when fitting my catch tank.

Anyway....

I then cleared all codes and went to start the engine again to get a new set of more precise faults but this time it wouldn't start without a lot of help from my foot on the accelerator and as soon as I let my foot off it splutters and then dies again.

Would a single faulty coil prevent the engine from starting?

I then decided to swap the coils from cylinders 1 and 2 to see what difference this made and still the same. When I re-ran VAG COM I got a misfire on 1 and 2 (using the spare coil) so I suspect that this spare coil may also be bad???

As nowhere is open on a Sunday I've now had to call out the RAC to come and swap them for some new coils to see if this is in fact the problem...

 

[knotty]

if its 2 cylinders next to each other then i would say that 2 failed coil packs would prevent it starting. Have you checked all the hoses? because i got that fault with a vacuum hose came loose

 

[Robbie C]

Yeah all hoses seem fine. The only ones I wasn't sure of were the vac hoses going to the underside of the inlet mani - one from the DV and one to the FPR but I can't see as it matters what port they go to? i.e there's two ports side by side on the inlet mani

 

[Robbie C]

I guess there's a slim chance that one bad one has weakened another one. I'll do some more VAG COM logging while swapping them over to see if there's a pattern I can trace

 

[__B3NNY__]

I`d be checking wiring/connections in thos areas as it could have been disturbed while removing the inlet and rocker cover.

 

[Robbie C]

10 points to Benny

After a lot of f**king around undoing and reconnecting things it looks to be running sweet as a nut again now. Still not 100% sure what it was in the end as I just lost track after a while

The RAC guy didn't wanna touch it when he saw it was modified and was about as much use as a **** flavoured lollypop but glad it's sorted now

 

[__B3NNY__]

Glad you sorted it mate.

I know the feeling Seat nor a local vag garage wanted to touch mine because of the modifications Hence the reason its now with Bill.

Free fix`s are always the best