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Missfiring 5cyl - 996 convertible --03

Solnaman
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Solnaman Member

Solnaman

Posted
Posted

Hi

I have just bought my first Porsche 911 and I have a bit of a problem. After 30km from the dealership the enginelight started, that is not good so I took the car to Porsche Center and they plugged the car in and got missfiring in cyl 5 and therefore they changed the sparkplug and the coil (i think coil is the word?) and the car started up and runned fine. Now a week later and 600km more after a big rainfall the englinelight went on again :( so another turn to PC and again missfiring in cyl 5. Accordingly to them they now need to take down the engine and change all the valves for a totalcost of 5500 euro.

Right now the independant Dealership from where I bought the car is refusing to handling the problem because that I have bought a used car with no factory warranty

Is this normal? This car is in extremly good condition externally and internally, fully served att porsche and has now gone 65000km on the speedomeeter.

/Magnus who mayby should have kept my SLK55 :huh:

KevinMac Member

KevinMac

Posted
Posted
Hi

I have just bought my first Porsche 911 and I have a bit of a problem. After 30km from the dealership the enginelight started, that is not good so I took the car to Porsche Center and they plugged the car in and got missfiring in cyl 5 and therefore they changed the sparkplug and the coil (i think coil is the word?) and the car started up and runned fine. Now a week later and 600km more after a big rainfall the englinelight went on again :( so another turn to PC and again missfiring in cyl 5. Accordingly to them they now need to take down the engine and change all the valves for a totalcost of 5500 euro.

Right now the independant Dealership from where I bought the car is refusing to handling the problem because that I have bought a used car with no factory warranty

Is this normal? This car is in extremly good condition externally and internally, fully served att porsche and has now gone 65000km on the speedomeeter.

/Magnus who mayby should have kept my SLK55 :huh:

If the rainfall was really part of the problem, it surely would not be the valves. Maybe the rain and the problem are coincedental, Was a compression check done and if so what were the numbers?. Where there any codes beside #5 missfire.

I would get a second opinion!

Solnaman Member

Solnaman

Posted
  • Author
Posted

thanks for the reply!

First time the missfire came directly after a fully recond, second time after rain...

There were no compression check done at this time.

No other codes exept the missfire

I think my english is making the wording wrong for me, i think the word not should be valve but instead Lifters?

Thanks in advance

Magnus

  • Moderators
RFM Member

RFM

Posted
  • Moderators
Posted

Good chance the OPC got it right, a faulty valve lifter. It is not necessary to change all the lifters, only the faulty one is needed. The engine can stay in place to do the job, just removing the exhaust and let sink the engine on the rear a little.

KevinMac Member

KevinMac

Posted
Posted
Good chance the OPC got it right, a faulty valve lifter. It is not necessary to change all the lifters, only the faulty one is needed. The engine can stay in place to do the job, just removing the exhaust and let sink the engine on the rear a little.

If that were the case you would have a noisey valve train, and this was not in the post. If the noise is not present, it sounds to me they are just throwing parts at it. Based on the post, I would be very skeptical about the diagnosis.

dr914jr Member

dr914jr

Posted
Posted

What about a failing injector? A failing lifter has a very distinctive sound. One that many 996 owners know all to well.

  • Moderators
RFM Member

RFM

Posted
  • Moderators
Posted

ROW 03 996 have the vario valve lift system, what means that the faulty lifter is blocked on full or minimum lift. The misfire fault appears because the cylinder receive more or less fuel mixture than the other cylinders. The lifter makes no noise at all. Noisy lifters can happen on < 02 996.

1999Porsche911 Member

1999Porsche911

Posted
Posted

Of coarse all lifters can make noise, regardless of engine type or manufacturer. I highly doubt your problem is a faulty lifter that requires engine rebuild. Although a possability. there are numerious things to look at before tearing an engine down. If you have little experience with engines, try another mechanic. I good mechanic can easily identify an electrical tick from a mechanical one as well as accurately locate the area from which the noise is coming from.

At minimum, I would run a quart Mystery Oil, Rislone Engine Treatment or similar solvent in your engine for a few hundred miles before I simply handed it over to a mechanic to tear it down in order to "investigate" the problem. Put in something better than Mobil 0W40 when you change the oil.

OCNYPORSCHE Member

OCNYPORSCHE

Posted
Posted

If you can get a code reader and post the codes, that will help a great amount. I had a similar problem and it was the coil pack. They are very picky and even if they are new, they need to be installed vey carefully. I would guess it can be as simple as removing the coil pack on 5 and then reinserting the coil. Cylinder 5 is acutally a tough one as far as the muffler bracket being in the way, so it is probably just the way that they put it back on. Easily can be an intermittent problem.

KevinMac Member

KevinMac

Posted
Posted
If you can get a code reader and post the codes, that will help a great amount. I had a similar problem and it was the coil pack. They are very picky and even if they are new, they need to be installed vey carefully. I would guess it can be as simple as removing the coil pack on 5 and then reinserting the coil. Cylinder 5 is acutally a tough one as far as the muffler bracket being in the way, so it is probably just the way that they put it back on. Easily can be an intermittent problem.

It could be just a bad connector to the coil that is causing you grief!

aracerx Member

aracerx

Posted
Posted
If you can get a code reader and post the codes, that will help a great amount. I had a similar problem and it was the coil pack. They are very picky and even if they are new, they need to be installed vey carefully. I would guess it can be as simple as removing the coil pack on 5 and then reinserting the coil. Cylinder 5 is acutally a tough one as far as the muffler bracket being in the way, so it is probably just the way that they put it back on. Easily can be an intermittent problem.

It could be just a bad connector to the coil that is causing you grief!

I would NOT DISCOUNT the intelligent comments of RFM-that guy is spot-on. :)? Marvel mystery oil--ha ha ha ha. Please, Im not taking a mickey on that but, with these machines! that cracked me up.....enjoy-Mark

  • 2 weeks later...
Solnaman Member

Solnaman

Posted
  • Author
Posted

So, the story continues

Now ALL of the coils and plug are replaced and the car did infact run fine for 2days...today.....CEL again...and you can hear that the engine aint firing good. Unfortinally I dont have a duramatic so I cant get hold of the codes in the weekend :( but my guess is that it still missfire in cyl 5 again

The shop did do a Compression check and a leakdown test and everything in that was in perfect condition.

Do anyone know how the person in this thread did get his very similar problem solved? http://www.renntech.org/forums/index.php?s...amp;hl=missfire

Anoyone have any idea of what I shall thy now? Fells like this was the worst idea ever to buy a porsche :(

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