Replacing spark plugs and coil packs..... well worth the effort!

[farmer boy]

Durametric was telling me I had a misfire on Cyl 6 so I elected to change all of the plugs and coil packs.  After reading the advice on here it was clear that it would be a fidldy job but good heavens, what a pain!!!  The plugs near the front are easy but the 2 at the rear are a nightmare.  Next time I think I shall get the local Indy to do it! 

 

Anyway - just to note that the difference is truly startling....  I am amazed how I must have got used to gradually decreasing performance without really noticing it.  She now pulls like a train and puts a huge grin on my face - well worth the effort and makes an outstanding difference. 

 

If yours are due for a change - do it!

[wross996TT]

Did you inspect the plugs and coil packs for indications of performance?

[farmer boy]

The old plugs actually looked ok (Bosch) but the coil packs were in a dreadful state.  All of the plastic cases were cracked and flaking although the metal bodies looked fine - just old age I guess. 

 

I fitted Beru plugs and the cheaper ARC coil packs (£16.50 each) and a couple of new heat shields - one was rusted to dust...

 

I guess the UK weather has taken it's toll on all of the stuff underneath!

 

So pleased with the improvement but a tricky job....

Edited April 17, 2015 by farmer boy

[Loren]

Ignition coils are easy to test (how they look is not really relevant).

Resistance between terminal 1 and terminal 15 at 20° C should be 0.3 - 0.7 Ohms.

[farmer boy]

Many thanks - I think they were the originals from 1998 so it seemed sensible to just change the lot whilst I was crawling underneath.... I have thrown them away now but thanks for the tip on how to test them.  (I may just get one out of the bin and try it)

 

Just a thought - I am sure they did not have 15 terminals - or is that a typo?

[Loren]

That is how Porsche labels them on the wiring diagram.

In Porsche terminology the following is true on all Porsche cars:

Terminal 31 = ground

Terminal 30 = unswitched power

Terminal 15 = switched power

 

 

[farmer boy]

Fabulous - I shall go and test them.... many thanks.

[SpawnyWhippet]

BTW, if you need to do this again, its much easier and quicker if you remove the exhaust mufflers first, just undo 3 bolts and a tube clamp on each side and they slide off. I can now do a complete spark plug change on a 996 in about 90 mins. The first time I tried took me most of the day when I was trying to slide all manners of extensions and universal joints in that tiny gap.

[Loren]

BTW, if you need to do this again, its much easier and quicker if you remove the exhaust mufflers first, just undo 3 bolts and a tube clamp on each side and they slide off. I can now do a complete spark plug change on a 996 in about 90 mins. The first time I tried took me most of the day when I was trying to slide all manners of extensions and universal joints in that tiny gap.

 

+1 I highly recommend this method - it can save you hours and hand injuries.

[farmer boy]

Ahhhh  that seems a much a more sensible idea.  I did think about removing the exhausts but the various nuts and bolts looked very corroded so I decided to leave them alone...  probably the wrong decision but still amazed at the difference it has made to the car.  I would not be surprised if I was running on the original plugs and coils!  Anyway it is now running better than it ever has and a new Idle air control valve has solved the tickover problem.  :)

[Odd Arne Klinge]

Just changed the spark plugs and coils on a friends 997, he could not be happier when we were done, the car ran perfectly. I did mine on my 996 last summer and they looked horrible, incredible any of them worked at all. The 997 coils were all produced in 2004, some had began to deteriorate, mine were all produced in 01 and would not last the season. If you have your original coils on your car (996) it is only a question of time as to when you have to replace them. Lastly it is a DIY, a bit fiddely, but with keyboard fingers and computer physics it should not be a problem :thumbup:. The first time it took about five hours, the second time not more than two, and if you dare to dismount the muffler it should be a jiffy. 

[Octane4evr]

Jumping in a bit late on this topic. I made an attempt last week to take on this task, first step was to remove the muffler. That's where I got stuck. Found the bolts and the pipe clamp but I couldn't wiggle the muffler out of it's spot. I have the Sport Exhaust, is there something special I need to do to get it out?

[Loren]

1 hour ago, Octane4evr said:

Jumping in a bit late on this topic. I made an attempt last week to take on this task, first step was to remove the muffler. That's where I got stuck. Found the bolts and the pipe clamp but I couldn't wiggle the muffler out of it's spot. I have the Sport Exhaust, is there something special I need to do to get it out?

 

Just disconnect the stainless steel vacuum line from each muffler -- rotate and drop down.

The rear wheels need to be off the car.

[Kdgiv]

On 4/23/2015 at 3:35 AM, farmer boy said:

Ahhhh  that seems a much a more sensible idea.  I did think about removing the exhausts but the various nuts and bolts looked very corroded so I decided to leave them alone...  probably the wrong decision but still amazed at the difference it has made to the car.  I would not be surprised if I was running on the original plugs and coils!  Anyway it is now running better than it ever has and a new Idle air control valve has solved the tickover problem.  :)

Hi, I have claimed my first love since I was a boy when I fell in love with the 911. I purchased a 2003 996 withjust under 60,000 miles. I had a misfire after some heavy rain and replaced No. 1 coil. Since then I have also replaced the motor mounts. I am planning on changing the rest of the coils and also the plugs. Farmer boy mentioned a "tickover problem" that he fixed with a new idle air control valve. Could someone explain the problem he was having?

[DBJoe996]

Remember, he is from the UK and probably is referring to idle.  When the ICV goes bad, mostly from being clogged up, the idle wanders, doesn't stay steady and the idle is either to high or to low.  Before you replace the ICV, always a good idea to remove it and clean it with carb cleaner while cycling it with a 9V battery. I soak it overnight and clean it with Q tips. At 139K miles I have had to clean mine several times due to unsteady idle.  Always solves that problem.

[Kdgiv]

Thanks for the explanation. So far so good. This issue hasn't come up for me yet.

[Schnell Gelb]

I just did a similar job. 2 suggestions. Check the spark plug tubes for oil leakage from the inner seal. Or you will have to repeat all the work. The seals are cheap and quick to fit when the coils and plugs are already out. There are some helpful comments.cautions and explanations from JFP here:

If your new tubes leak 7/or are hard to remove, here is the reason i found. The inner end of the tubes may be out of round ! The outer end may be oversize. I used the aftermarket tubes that came as a part of a "Conversion Set'. The replacements from Sunset were perfect.

The other hint is to examine the coils in very bright light when they are clean and dry. Only after this step did I notice the beginnings of hairline cracks on all 6 coils.They were also a little discolored. The resistance test that Loren kindly mentioned previously showed the coils were electrically perfect. I had misfire on all 3 cylinders on Bank 1.The new coils+ plugs+tubes fixed it.

There is an upgrade to the old coils that also requires longer bolts - the 'head' of the coil is thicker. So I just replaced them on a 'while you are in there' basis .

Edited March 24, 2017 by Schnell Gelb

[Ddavidoff]

I have to agree with the while you're in there comment. Why spend all the time taking things apart to do half the job. Did mine this winter. Plugs, coils, new tubes and seals.


I then decided to do the AOS and following the while you're in there idea: new vacuum lines, oil fill tube and seal, coolant tank etc.. Also tested the vacuum canister for leaks and almost did the starter, but it looked like it was in good shape. Also, had a good look over the starter power wire that is known to have issues, but mine was in great shape. Maybe it was already replaced. Also found that the vacuum line had come out of the intake plenum and the intake had sprayed oil all over the top of the engine. Cleaned all of that up and put it back together. Also found the temp sensor had been taken out of its holder on the right side of the intake.

Also, changed the trans fluid and while doing that replaced the fuel filter which is in the same area.

Ordered some coilovers and some new tires. Probably need a fender roll in the rear so that will be a task for the next few weeks.


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[Schnell Gelb]

" Also found the temp sensor had been taken out of its holder on the right side of the intake. "

There may have been a reason for that .

In doing so, it ensured the engine compartment cooling/purge air fan came on at a lower temperature and stayed on for longer. I am not recommending this but have read that it is a popular hack/mod with some others. The temperatures under there are so high during heat  soak, I presume that accelerates the  degradation of some plastics that bedevils the older M96. And there are a lot of inaccessible ,crucial plastic parts under there as you've recently discovered!

[Ddavidoff]

" Also found the temp sensor had been taken out of its holder on the right side of the intake. "
There may have been a reason for that .
In doing so, it ensured the engine compartment cooling/purge air fan came on at a lower temperature and stayed on for longer. I am not recommending this but have read that it is a popular hack/mod with some others. The temperatures under there are so high during heat  soak, I presume that accelerates the  degradation of some plastics that bedevils the older M96. And there are a lot of inaccessible ,crucial plastic parts under there as you've recently discovered!

Interesting. I will do some research. Thanks for the info.
I live in Canada so we don't see the heat like southern cars do, but this one came from Cali so that might explain it.


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[Montychristo128]

On 4/22/2015 at 2:06 PM, SpawnyWhippet said:

BTW, if you need to do this again, its much easier and quicker if you remove the exhaust mufflers first, just undo 3 bolts and a tube clamp on each side and they slide off. I can now do a complete spark plug change on a 996 in about 90 mins. The first time I tried took me most of the day when I was trying to slide all manners of extensions and universal joints in that tiny gap.

 If you drop the engine down on the mounts its not so bad for access I reckon I can probably remove reinstall all mine in less than an hour. I would say impossible otherwise, unless you remove the exhaust. 

[Octane4evr]

I haven't done my plugs and coils yet, planning on it in the next couple of weeks. But in looking at the access, I'm wondering why people don't just remove the header. Seems like doing that would provide excellent access to the coils and plugs. Any reason not to do that?

[Loren]

58 minutes ago, Octane4evr said:

I haven't done my plugs and coils yet, planning on it in the next couple of weeks. But in looking at the access, I'm wondering why people don't just remove the header. Seems like doing that would provide excellent access to the coils and plugs. Any reason not to do that?

 

Not the headers but the mufflers - removing the mufflers makes the job easy,

 

[Hilux2400]

I agree - it's much easier without the silencers on.

[Ddavidoff]

I agree - it's much easier without the silencers on.

A good time for a cleaning as well



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