2005 206 1.6 petrol - coil pack testing?

[SteveFrenchCar]

Hello everyone,

First post here, perhaps somebody could help me out.

Is there any way I can perform a resistance test on the primary and secondary wiring of the above coil pack? I know how to test if a car has separate coil packs, but my 206 has a 'coil-on-rail' coil pack (if that is the correct description).

I am trying to eliminate the coil pack as a source of a reported misfire in cylinder no. 3, before I move on to check other possibilities.

Many thanks in anticipation

Stephen

[ozvtr]

Sorry, but "1.6 petrol" is not enough to identify the engine type. What is the 6th, 7th and 8th characters of your VIN?

If I assume its a TU5 engine, it uses a "wasted spark ignition". Meaning that there are only 2 coils in the coil pack. The spark plugs in cylinders 1 and 4 are on one coil and cylinders 2 and 3 are on the other. The plugs form a series circuit on each of the coils meaning the spark current goes through one plug then through the other. So if it was a coil problem, cylinders 2 and 3 would show a miss fire.
Could be the boot over the top of the spark plug is bad and it's sparking to the cylinder head.
Crack in the spark plug porcelain?
Any oil in the spark plug well?
Might be a head gasket problem.
Could be the fuel injector.

[PaulC5]

When you plug it in to a code reader what if any fault codes are you getting ?

You can check the spark plugs by swapping them over cylinders if there is nothing obviously wrong with them. Bear in mind the cylinders are probably numbered from the gear box end, unlike other makes of car. If like the 2003 C3 we had, from memory, there is an earth wire at the gearbox end of the cylinder head that breaks if not careful when removing the coil pack.

This C3 also had a bad misfire and it was an injector fault - looking at it there was rust on its coil which gave it away, fixed by replacing it. The fault code pointed to it being faulty.

[ozvtr]

If like the 2003 C3 we had, from memory, there is an earth wire at the gearbox end of the cylinder head that breaks if not careful when removing the coil pack.

This was the earth for the shielding over the feedback from the coil pack to the engine ECU. In later models it was replaced with a capacitor (from the shielding to the engine block).
90% of the time, breaking this earth made no difference. But on some cars it would cause random engine errors. Don't know why it affected some and not others.

[SteveFrenchCar]

Sorry, but "1.6 petrol" is not enough to identify the engine type. What is the 6th, 7th and 8th characters of your VIN?

If I assume its a TU5 engine, it uses a "wasted spark ignition". Meaning that there are only 2 coils in the coil pack. The spark plugs in cylinders 1 and 4 are on one coil and cylinders 2 and 3 are on the other. The plugs form a series circuit on each of the coils meaning the spark current goes through one plug then through the other. So if it was a coil problem, cylinders 2 and 3 would show a miss fire.
Could be the boot over the top of the spark plug is bad and it's sparking to the cylinder head.
Crack in the spark plug porcelain?
Any oil in the spark plug well?
Might be a head gasket problem.
Could be the fuel injector.

Hi, thanks for that, a very informative reply.

The 3 VIN characters you ask for are NFU. I believe it is a TU5JP (according to Haynes).
My diagnostic code reader (a Topdon ArtiDiag 600S) is only showing 2 DTCs : P1336 (permanent fault) Misfire on undetermined cylinders, and P1339 (permanent fault) Combustion misfiring on cylinder no. 3. So I assume therefore that it is not a coil problem, as there is no DTC for cylinder no 2.
To date I have removed the coil pack and the plugs. There appears to be no damage to any boots. I have already swapped no 3 plug with no 4, reassembled, and DTCs remain the same. No oil in the spark plug well. Head gasket - I have not yet done a compression test. And yes, I'm beginning to suspect an injector no 3 problem. That will be the next thing to investigate.

Many thanks

[ozvtr]

The P1336 and P1339 are going to be the same thing.

You can do the same as PaulC5 suggests, and swap the injectors around and see if the fault moves. Remember, the cylinders are numbered from the gearbox end, NOT the crankshaft pulley end!

Take your time removing the injectors, they will be stuck in the head! Squirt a bit of WD-40 (or whatever) down the injector hole to lube the orings before you attempt to remove the injectors. Use a bit of Vaseline or preferably silicone lube on the orings of the injectors before installing them back into the fuel rail and cylinder head. Again, take your time installing the injectors into the head, you don't want to "roll" the orings and cause a vacuum leak.

Before you install the injectors back into the fuel rail, put the retaining clip onto the fuel injector, THEN clip the injector and retainer into the fuel rail.

Head gasket failure is a bit of a stretch as the TU5 engines are pretty reliable in that department, but it's a remote possibility.

[SteveFrenchCar]

When you plug it in to a code reader what if any fault codes are you getting ?

You can check the spark plugs by swapping them over cylinders if there is nothing obviously wrong with them. Bear in mind the cylinders are probably numbered from the gear box end, unlike other makes of car. If like the 2003 C3 we had, from memory, there is an earth wire at the gearbox end of the cylinder head that breaks if not careful when removing the coil pack.

This C3 also had a bad misfire and it was an injector fault - looking at it there was rust on its coil which gave it away, fixed by replacing it. The fault code pointed to it being faulty.

Hi PaulC5

Thanks for replying.

I have replied to ozvtr's comment, in which I covered your points. I am thinking it may be an injector fault, I will check that out.

Thanks again, much appreciated.

[SteveFrenchCar]

The P1336 and P1339 are going to be the same thing.

You can do the same as PaulC5 suggests, and swap the injectors around and see if the fault moves. Remember, the cylinders are numbered from the gearbox end, NOT the crankshaft pulley end!

Take your time removing the injectors, they will be stuck in the head! Squirt a bit of WD-40 (or whatever) down the injector hole to lube the orings before you attempt to remove the injectors. Use a bit of Vaseline or preferably silicone lube on the orings of the injectors before installing them back into the fuel rail and cylinder head. Again, take your time installing the injectors into the head, you don't want to "roll" the orings and cause a vacuum leak.

Before you install the injectors back into the fuel rail, put the retaining clip onto the fuel injector, THEN clip the injector and retainer into the fuel rail.

Head gasket failure is a bit of a stretch as the TU5 engines are pretty reliable in that department, but it's a remote possibility.

Hi ozvtr

That is brilliant advice, thank you so much.

I shall do that next.

Many thanks.