Porsche 997.1 technical advice coil pack/spark plugs

[YoungMD]

Some technical advice would be greatly appreciated. I recently changed the spark plugs and three ignition coils (they were badly damaged but the others looked okay), to complicate matters i also put a low temp thermostat in.

Anyway started the car to do the water bleeding process etc, and the car is running rough/misfiring to say the least, with a yellow engine light.

From what i can determine the issue could be with not changing all the ignition coils, so my questions are:

1) should i just change the other 3 coils (the 3 i actually fitted were the newer fatter one and the others are the 'old' type) [they did not have more than 3 in stock but the others looked fine?

2) should i take to car to the dealer and get the fault codes read, although don't fancy driving it with a flashing yellow engine light?

3) maybe its something to do with the low temp sensor, although i fail to see how you could get changing that wrong....but you never know....

Any help, guidance, advice much appreciated...................

[YoungMD]

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[YoungMD]

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[Trev450]

I've heard of instances where not changing all six of the coil packs has caused a misfire so that would be my first option. I cannot think of any reason why changing a thermostat would cause a misfire unless you inadvertently disturbed something else.

Edited by Trev450 on Sunday 24th January 17:26

[Demort]

well ... if the car was running fine before you changed the thermostate and coils and isnt now then i would lean towards something going wrong with the job.

Did all the coils plugs get pushed in far enough and clip in place ?
Did you unplug anything else ( vario cam solioid ) and not refit ?

I cant think of anything on the thermostae job that would cause the running problem but re look at what you did perhaps.

It is possible for the other coils to have failed but that would be a hell of a coincidence to fail just as you did some work.

It is also possible that you fitted defective coils .

Need a tester to see which cyl is missfireing really.


Any ways this is what i whould do if the same thing happened to me


You also changed the spark plugs .. ill bet a fiver that one of the plugs is defective , probably a bent pin

[LotusAlfaV6bloke]

One of the coils didn't "click" on properly.

Or, but much more unlikely, one of the new parts is a duff.

You can get a code reader for the price of two coils that will give you the breakdown of your breakdowns! Then you'll know which to look at again.

[YoungMD]

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[YoungMD]

LotusAlfaV6bloke said:

One of the coils didn't "click" on properly.

Or, but much more unlikely, one of the new parts is a duff.

You can get a code reader for the price of two coils that will give you the breakdown of your breakdowns! Then you'll know which to look at again.

Many thanks for the comments, i did take all the coils out as i changed the spark plugs so i was thinking that one of the old ones is probably playing up now it has been disturbed, all the new ones seem to go in okay, the real pain is that i had the exhaust off so it was easy, now not so easy :-(

Be very interested to understand what code reader you can buy cheaply to detect what cylinders is misfiring???

[c4sman]

Thinks it's worth changing remaining pack either way as chances are if one is faulty they all are heading that way.

[YoungMD]

c4sman said:

Thinks it's worth changing remaining pack either way as chances are if one is faulty they all are heading that way.

I agree will do that, shame though will not be as easy with the exhausts on, although could not check them with exhaust off......

[LotusAlfaV6bloke]

I use an iCarsoft i960, which are under £100 and far less second hand

[YoungMD]

LotusAlfaV6bloke said:

I use an iCarsoft i960, which are under £100 and far less second hand

do you use it for a few things, is it generally handy, just wondering in practice if it is very useful?

[LotusAlfaV6bloke]

It only really does the DME (engine fault codes). But these cars are pretty old now,its a handy gadget to have. Instant diagnosis of my failed coilpacks, crank sensors...

[YoungMD]

Hi there, so firstly thanks for the advice, it was the coils, basically one of the old ones was slightly not connected properly on top to the low voltage connector (very flimsy i must say). Going to change all the other three coils anyway so its done for a while. Have to say once you have done it a couple of times its pretty easy (bar the two very rear ones which are a bugger).

Just a final question, the car is running fine, but the yellow engine light is still on, presumably this stays on now until it is cleared? not at all familiar with such things (all my other porsches were air cooled, back in the day when they were affordable)

If so what is the cheapest way to get rid of the yellow light? or does it mean it still has a fault, which would be hard to understand as it is now running fine.

Many thanks indeed !