Macster

If the coil was the cause of the misfire replacing the coil should have not resulted in another misfire code. The Ecu constantly checks and rechecks for misfire conditions so if a misfire code is logged it is not due to stale info.

There is a slim chance the new coil is bad, or mis-installed, so it might be worth the effort to swap the 'bad' coil with a good one and of course be darned sure both coils are installed correctly then see if the misfire follows the coil or remains with the cylinder.

If it remains with the cylinder.... what did the plugs look like? Any notable differences between the plugs?

A misfire that occurs and is not related to a bad plug or coil could be a burned valve, or something in the valve hardware, a bad lifter or a cam lobe that has gone flat.

Unless you find something external to account for the misfire I think you might consider a compression test and possibly a leak down test. There's a problem and one/both of these tests will help you and your mechanic narrow down the possible problems. For instance if a leak down test finds the cylinder not holding pressure then a listen at the intake and exhaust can help one decide if the problem is with an intake valve or an exhaust valve.

Sincerely,

Macster.

jrm87

Its fixed! Thanks so much for everyone's help and input. The coil pack connector on the 1st cylinder wasn't clipped into place and the connection wasn't good.
I saved $600 compared to taking it to the dealer so thanks again!

wyovino

Great news!

Barn996

I'm so glad I'm going to drive my Porsche tonight in celebration for your 'fix'.

jrm87

Apparently my car is not fixed. I put it new coils and plugs and re-checked the plug connections. The car ran well for about 2 days and now Im randomly getting different cylinder misfires. The original coils are part number 996 602 102 00 beru 0040 100 021. The new ones are 997 602 107 00 beru 0040 100 031. I think this new number just replaced the old one? Am I correct here? The service manager at the dealer said they weren't porsche coils and they needed to be changed again, but I think he was an idiot. Does anyone know what could be the issue here? My recent codes are P0300,P0301,P0306. But they keep changing around. The dealer pulled codes 301,303,305, and 306. This is very confusing. Im going to take it to Stuttgart Specialist's next week if I cant figure this out. Any input if much appreciated. Thanks again.

logray

The latest (replacement) coil P/N for 996 is 99760210700 for 99-01 and 99760210400 for 02-05.

I suggest following the misfire troubleshooting guide I posted earlier religiously.

Since your misfires are on both banks and seemingly random, I would focus on common items such as MAF, DME, intake leaks, proper installation and type of of packs/wires/plugs.

Macster

Hard to imagine if the coils were new and had the correct part number that clearly indicated the coils were for your car's model, at least at some point, that the coils could be the the cause of the misfires.

The dealer is just (probably) going by the book and that is the car's VIN is used to look up the part numbers for the coils and 997 602 107 00 comes up and if the coils you are using do not have that part number (and if the engine is manifesting misfire error codes, random codes that often are due to bad coils) that the dealer is going to say what it said.

OTOH, even though the coils you bought have the right number they may not be the same coils as they were some years ago. Porsche may have moved to the 997 coils simply because the coil maker changed something and the coils with the otherwise right but older part number are no longer are suitable.

The parts department managers I talk to always tell me to when I want to order parts for my Porsche cars to order them based on the VIN. Porsche ties parts numbers to VINs and over time parts either go away, or are replaced by parts with different numbers.

Also, I know many do not like to read this but I often have my doubts that discounted parts even though they are claimed to be the same as 'factory', are actually that, that they have have the same characteristics and quality that the parts handed to you over a Porsche parts counter have.

To state the obvious, you have to eliminate other possible causes of the misfires or the coils become suspect. Or you replace the coils with the 'right' coils and then go from there.

Added: The misfiring may be caused by say improper fueling. This may arise from a bad air intake temp value (this comes from the MAF) or from a coolant temp sensor. If the temp reported by the sensor is higher than actual the DME will not provide a rich enough mixture for the cold engine and misfires can result. If the check engine light doesn't flash the misfires aren't severe enough to put the coverters at risk of overheating from unburned fuel from the engine being combusted in the converters.

You can disconnect the MAF from the wiring harness, clear the codes to clear/reset all learned fueling back to their defaults, and start the engine drive the car as you have in the past to see if the symptoms/codes reappear.

Or you can with an OBD code reader/data viewer/logger view the intake air and coolant temps at cold engine start and compare them to each other and ambient and if you spot any big differences in readings the reading furthest from actual points to the suspect sensor.

Sincerely,

Macster.