Check Engine Light at High RPM

[Haiyan]

Hi everyone.

I have a Porsche Carrera 996 3.4L 2001 model with 160K km on the dash. I'm facing problem with my engine which is when I go over 5500 RPM the check engine light will flash for several seconds than it will go also it feels that the car loss power when at that RPM range and above also at the first gear I don't get the CEL but from the second gear to the sixth gear I will be getting CEL anytime I go above 5500 RPM. However, I thought that the car need some major service so I have changed the following:
1- engine oil (5w50) and filter

2- air filter

3- fuel filter

4- spark plugs 

5- ignition coils ( I had a misfire because of one ignition coil went bad and a CEL was on but once I replaced all of the ignition coils everything went back to normal and the car idle and drive smooth )

6- engine belt 

7- three pulleys 

8- manual transmission oil 

9- differential seals 

10- engine rear seal ( gearbox side )

11- manual transmission seal

12- alternator rebuild ( without changing the alternator pulley )

13- both radiotors ( little bigger with more capacity than the stock radiators )

14- coolant 

15- power steering fluid 

16- brake fluid 

17- Battery ( Bosch S4 80 AH )

 

When the engine is cold and I start it the oil pressure will be at 4 and once the engine is hot ( like driving for more than half hour or so ) the pressure will drop to 0.5, also when accelerating to 5500 RPM the pressure will be at 4 or a little bit above 4 but won't reach 5. in addition I noticed that the right side exhaust has black residue but the left exhaust is clean. Also the voltage when I put the ignition on it shows 12v and once I start the car it will sit between 12v and 14v depending if the headlights or the ac is on but generally when everything is on the voltage will be at the middle between 12v and 14v and with just the engine on it will be a bit higher near the 14v but won't exceed.

 

Once I drove the car for more than an hour and when I came to a traffic signal down shifting when I hit the clutch to shift gears the RPM dropped to 0 and the dash lights came on I stopped the car and turn the ignition off than tried to start it ageing and it worked fine but took a few seconds to start like one or two seconds.

 

Any ideas on what might be the problem with my car?

Thank 

 

[RFM]

As Always, error codes are required. Let the car scan and quote the codes here on the forum so members can help more targeted, as indicated it could be anything. Guesswork is not recommended and rarely produces some positive results.

[JFP in PA]

As Always, error codes are required. Let the car scan and quote the codes here on the forum so members can help more targeted, as indicated it could be anything. Guesswork is not recommended and rarely produces some positive results.

 

+1.  If the car is setting off the CEL, the DME is carrying data to tell you what is going on.  Get the car scanned with a Porsche specific scan tool.

[Haiyan]

I will try to get the code as soon as the dealer is open. 

 

Many thanks guys

[Haiyan]

I've got the codes...
P0300 - Misfire detection (total) (exceeds limit value)
P0306 - Misfire, Cylinder 6 (exceeds limit value)

 

These are stored but not active even when we tried to rev the car nothing happen just normal no code have been stored in the DME

Edited August 10, 2014 by Hayyan Al-Raisi

[JFP in PA]

I've got the codes...

P0300 - Misfire detection (total) (exceeds limit value)

P0306 - Misfire, Cylinder 6 (exceeds limit value)

 

These are stored but not active even when we tried to rev the car nothing happen just normal no code have been stored in the DME

 

Both are cylinder misfire codes, pointing to the #6 cylinder.   Check the coil pack connections on that cylinder, and pull the plug and look at it.

[Haiyan]

 

I've got the codes...

P0300 - Misfire detection (total) (exceeds limit value)

P0306 - Misfire, Cylinder 6 (exceeds limit value)

 

These are stored but not active even when we tried to rev the car nothing happen just normal no code have been stored in the DME

 

Both are cylinder misfire codes, pointing to the #6 cylinder.   Check the coil pack connections on that cylinder, and pull the plug and look at it.

 

I will check that because I have a misfire on that cylinder and I drove that car for a bit long before I put it in the shop for changing the ignition coils, could it be the spark plug needs to be changed? also the dealer says that it might be from the fuel injectors or the fuel pump...could it be? 

[JFP in PA]

 

 

I've got the codes...

P0300 - Misfire detection (total) (exceeds limit value)

P0306 - Misfire, Cylinder 6 (exceeds limit value)

 

These are stored but not active even when we tried to rev the car nothing happen just normal no code have been stored in the DME

 

Both are cylinder misfire codes, pointing to the #6 cylinder.   Check the coil pack connections on that cylinder, and pull the plug and look at it.

 

I will check that because I have a misfire on that cylinder and I drove that car for a bit long before I put it in the shop for changing the ignition coils, could it be the spark plug needs to be changed? also the dealer says that it might be from the fuel injectors or the fuel pump...could it be? 

 

 

Could be a bad plug, or even just a loose coil pack connector.  A bad fuel pump would impact more than one cylinder, and a bad injector should show up in the fuel air mixture data and throw a different code.

[Haiyan]

 

 

 

I've got the codes...

P0300 - Misfire detection (total) (exceeds limit value)

P0306 - Misfire, Cylinder 6 (exceeds limit value)

 

These are stored but not active even when we tried to rev the car nothing happen just normal no code have been stored in the DME

 

Both are cylinder misfire codes, pointing to the #6 cylinder.   Check the coil pack connections on that cylinder, and pull the plug and look at it.

 

I will check that because I have a misfire on that cylinder and I drove that car for a bit long before I put it in the shop for changing the ignition coils, could it be the spark plug needs to be changed? also the dealer says that it might be from the fuel injectors or the fuel pump...could it be? 

 

 

Could be a bad plug, or even just a loose coil pack connector.  A bad fuel pump would impact more than one cylinder, and a bad injector should show up in the fuel air mixture data and throw a different code.

 

Thanks for clarifying this point. I will check the coils connection and the plugs. many thanks.

[judgejon]

yes, plugs and coils seems right, but since you recently changed them my bet would be the problem is a loose connector.

Good luck.

[boxster-s-dk]

Sounds like coil pack or maybe check camshaft deviation, worst case might be IMS bearing that is on the way out, so it turns on engine fault??

Your oil pressure is still very low, when idle hot.

I have 2,2 bar hot, and 4,5 when cold...I use Millers Nanodrive 10w-50 (but only 2 years old engine)

Good luck

Stefan

Denmark

Edited August 14, 2014 by boxster-s-dk

[Haiyan]

Just to update..got the car up and removed all of the coils and plugs cleaned the sparks and shifted them around also the ignition coils but still the same misfire I have on cylinder 6. However, I added some fuel system cleaner and drove the car hard the weird thing is when the CEL doesn't show all the times previously I had it from 2nd gear to the 6th but now the 1st and 2nd I don't get any CEL only at 3rd gear upwards and not all the times also sometimes I get a misfire on cylinder 6,5,4

 

I noticed that all of the spark plugs are black but dry so could it be that I'm having a cold spark plugs? because the dealer fitted the Bosch FGR5KQE and when I checked with Pelicanpart.com they show the Bosch FGR6KQE as a replacement spark plug for the Carrera 996 which is a hotter plug when compared with the FGR5KQE which is fitted right now.

 

Many thanks

[JFP in PA]

My reference says the OEM plugs for your 3.4L are Beru 14 -gr-6-kqu, which should cross reference to a Bosch FGR6KQE, so you are running a bit too cold.  Black velvety or sooty looking plugs are a sign of an overly rich condtion, so if a hotter plug does not clean up, I would start looking at your intake system for reasons why.

[Haiyan]

My reference says the OEM plugs for your 3.4L are Beru 14 -gr-6-kqu, which should cross reference to a Bosch FGR6KQE, so you are running a bit too cold.  Black velvety or sooty looking plugs are a sign of an overly rich condtion, so if a hotter plug does not clean up, I would start looking at your intake system for reasons why.

 

Thanks JFP for clearing this thing up for me I will change the sparks from the FGR5KQE to FGR6KQE and will report back. Many thanks.

[Scott Scott]

had a similar problem with my MY 2004 996. after many months of replacing varoius parts my mechanic traced the problem to bad cats.

[Haiyan]

Just to update Yesterday I have changed the spark plugs to the correct ones and the problem still there. However, I removed the catalytic converters and I have found that the two of them are clogged + one is broken from the inside so I removed them and everything went back to normal no misfire at high rpm also it runs much smoother than before.

[Silver_TT]

Glad you got it sorted.  It likely depends on a number of factors but there are quite a few 996's out there that had cats which didn't make it past 100K miles.  In my case, it was certainly from vibration and I suspect it was, at least in part, in your case too as you saw the element was broken inside when you took the cats off.  It's just speculation but your cats could have been clogged as a result of the engine running too rich (due to this issue).  If you still have the old cats you can likely get a couple hundred bucks for them at a scrap metal shop -- it's not much but better than nothing.

Edited November 10, 2014 by Silver_TT

[Scott Scott]

It doesn't have to be high mileage - my 996 had only 24k miles and the cats were broken up and plugged. Just wondering what you did to replace them? I added a central muffler (cat delete) and ECU chip for about 10% more engine output and an amazing exhaust sound.

[Silver_TT]

Hard to really measure it by mileage since there are so many factors involved.  However, I will say that I previously throught cat issues to be much more rare than they actually are on these cars.  That said, 24K miles isn't much to get out of a cat (they cost some serious $$$).  Mine occurred at much later mileage than yours and I stuck with OEM's.  Some people might say I'm crazy and wasted money but there are too many problems with emissions in the state I was in.  Cat deletes and ECU modifications are easy pick-offs for them.  It was my daily driver so I can't really afford to not have a car that's legal to drive unless I want to take the train to/from work every day in rain, snow, or shine.