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srfrdrew

Blinking CEL with Codes P0300, P0301, P0304

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I've had this issue a while ago but resolved after changing sparks and oil, but it has come back for some reason...

 

2001 996 Cabriolet with ~61K on the odo

 

it was fine this morning going into work...Started engine this afternoon, engine immediately rough idle, with blinking CEL.

 

Was told by Porsche Dealership (master tech) if and when this happens in neutral to increase RPMs for about a minute or so and then turn off engine and restart.

 

Did that a couple of times and engine refresh and idled smoothly again.  CEL remained on and lit but no blinky

 

Pulled codes with generic scanner P0300, P0301, P0304

 

I was told by Porsche Dealership (master tech) that it could be a "sticky" lifters...  He said they are very small and could be gummed up etc...

 

Any ideas? Thoughts? Suggestions?

 

Much appreciated, Happy new year! (way to start it out for me with this issue!)

 

 

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I've had this issue a while ago but resolved after changing sparks and oil, but it has come back for some reason...

 

2001 996 Cabriolet with ~61K on the odo

 

it was fine this morning going into work...Started engine this afternoon, engine immediately rough idle, with blinking CEL.

 

Was told by Porsche Dealership (master tech) if and when this happens in neutral to increase RPMs for about a minute or so and then turn off engine and restart.

 

Did that a couple of times and engine refresh and idled smoothly again.  CEL remained on and lit but no blinky

 

Pulled codes with generic scanner P0300, P0301, P0304

 

I was told by Porsche Dealership (master tech) that it could be a "sticky" lifters...  He said they are very small and could be gummed up etc...

 

Any ideas? Thoughts? Suggestions?

 

Much appreciated, Happy new year! (way to start it out for me with this issue!)

 

You are throwing misfire codes for cylinders 1 and 4.  Could be a number of things (coil packs, plugs, etc.).  Clear the codes and see if they return; it could have just been a momentary thing.

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I was checking my oil level and looked under the filler tube/cap this is what I'm seeing...Light brown creamy substance...

 

My first thought was intermix however the CET looks clean and clear.

 

I read that this substance is common is oil and water vapor from running the car on short trips which do not allow it to burn off the moisture in the oil.

 

Not sure if this could be related to what is going on with the misfire.

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I was checking my oil level and looked under the filler tube/cap this is what I'm seeing...Light brown creamy substance...

 

My first thought was intermix however the CET looks clean and clear.

 

I read that this substance is common is oil and water vapor from running the car on short trips which do not allow it to burn off the moisture in the oil.

 

Not sure if this could be related to what is going on with the misfire.

 

Most likely not; as you noted, it is a common occurrence on these vehicles.  The most common misfire areas are spark (or lack there of) and fuel (overly lean/rich mixtures).  Fuel issues tend to throw emissions codes, so I would start by checking the coil packs (common problem area) and plugs.

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Do you think this may be due to a clogged fuel filter?  I believe this 996 is still running on its original filter.

 

I would think that if that was the case it would effect the whole engine and not just certain cylinders.

 

The plugs were changed about a year ago because of this issue cropping up but I do not think the coil packs were replaced.

 

There is no deeper scan to do other than to start replacing Coil packs (and plugs again) for cylinders 1 and 4 ?

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Do you think this may be due to a clogged fuel filter?  I believe this 996 is still running on its original filter.

 

I would think that if that was the case it would effect the whole engine and not just certain cylinders.

 

The plugs were changed about a year ago because of this issue cropping up but I do not think the coil packs were replaced.

 

There is no deeper scan to do other than to start replacing Coil packs (and plugs again) for cylinders 1 and 4 ?

 

If the fuel filter clogged, all the cylinders would begin to lean out and you would get an overly lean code from the O2 sensors, so I don't think it is necessarily that.  You should also be able to see a clogged filter with a fuel pressure and delivery test.

 

As I do not know what facilities you have at your disposal, I would suggest getting the car scanned on a Porsche specific diagnostic system ( Durametric, PIWIS, PST II), looking for anything out of the ordinary (strange responses from the O2 sensors, fuel trims, etc.).  As cylinders 1 & 4 look like a starting point, I would also pay close attention to them, pull the plugs and coil packs, closely checking them for any discoloration on the plugs, cracked ceramics, loose coil pack connectors, cracks in the coil packs themselves, etc.).  While some parts may need to be replaced, I would not replace them without knowing why.

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10-4 JFP, thanks for the sage advise...  I'm waiting on that MaxiDAS 708DS to show up and may get some further clues as well.

 

I may just change out those offending plugs and the complete coilpack set as a package deal, the time to get to them and look, may as well change them out anyway.

 

Quickly back on the brownish creamy sludge in the oil filler tube.  I'm reading that Mobil 1 0-40 that I been using may be more water prone than others such as Motul?

 

Do you recommend switching to a Motul oil or just change Mobil 1 more frequently?

 

I'm thinking that possible misfiring due to condensation due the outside temp and that the engine did not have time to burn off excess moisture inside causing the misfire?  Just stabbing at possibilities

Edited by srfrdrew

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Coil pack failures seem to be relatively common on the 996.  If they are still original they are probably due for replacement and could easily be the cause.  Mine failed last year with similar symptoms while driving in heavy rain.  If the misfire occurs more frequently when the car is wet or damp it is a good indicator of cracked coil packs.

 

ECS tuning sells a set of coil packs and spark plugs for less than $300 (if I remember right).

 

Replacing them is fairly straightforward although getting easy access requires removing the mufflers which can be a bit of work especially if the exhaust bolts are heavily rusted.

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Thanks for the advice kgoertz, looking at others with same issues as well.. Could also be as simple as a fuel cap not sealing properly either.  But I think it is time to change plugs and packs, the plugs were changed about a year or so ago and not sure if the packs were ever changed out (probably original)

 

From the DIY's I've seen you don't need to drop the exhaust to pull and replace the plugs and packs

Edited by srfrdrew

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10-4 JFP, thanks for the sage advise...  I'm waiting on that MaxiDAS 708DS to show up and may get some further clues as well.

 

I may just change out those offending plugs and the complete coilpack set as a package deal, the time to get to them and look, may as well change them out anyway.

 

Quickly back on the brownish creamy sludge in the oil filler tube.  I'm reading that Mobil 1 0-40 that I been using may be more water prone than others such as Motul?

 

Do you recommend switching to a Motul oil or just change Mobil 1 more frequently?

 

I'm thinking that possible misfiring due to condensation due the outside temp and that the engine did not have time to burn off excess moisture inside causing the misfire?  Just stabbing at possibilities

 I am not a fan of Mobil 1 products.  Some of the Motul oils are pretty good, but if I were you I would be looking at Joe Gibbs DT40.

 

I have never heard of internal moisture build up leading to misfires, but even slightly cracked coil packs will, particularly if it is raining or wet out.  Moisture inside the engine is not a function of oil brand or type, it ususally stems from the engine not getting hot enough to burn it off from things like short trips.

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Could also be as simple as a fuel cap not sealing properly either. 

 

If it was a loose gas cap, you would get a specific code of a large EVAP system leak.

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