Misfires
 

I'm getting misfires in my 04 996tt in almost every gear under high boost. The misfires occur in the 4-5krpm range. Under normal driving I get very few if any. I have an ECU flash, but I don't know which one because it was done by the previous owner. It's supposed to be running about 500 hp.

Has anyone else had this? I'm planning on having new coil packs and plugs installed this week, but I'm wondering if I should be looking elsewhere.

Hi,
post the codes if you can read them. If not find some body with a Durametric. Can be many reasons for a misfire. Best start with the codes.
and go on from there.
Frank.

The weird thing is that I'm not getting any CELs when it happens. Is that normal?

Classic symptoms of plugs and/or coil packs

Sorry not sure. The last misfire I had was in my Cayenne Turbo. Coil packs failed. Went into limp home mode and CEL. I am a bit surprised to hear that you have no CEL though.
Check the dme codes they will tell you the possible reasons for the misfire.
There are those on this forum who will have forgotten more than I know about 996tt.LOL .
Having one its a sharp learning curve and I am still learning. LOL.

It won't set a CEL for a misfire. it will however, continue to miss and get worse. These cars are notorious for misfiring, especially flashed with more boost. Plugs and coils will likely fix it. Shop around. Coils are usually $250-$300 a set, don't pay more. Do a search for plugs. Many have opinions...hilarious

I've had misfires and get CELs with every one.

OP- Does you CEL Light work??? It should come on when you turn the key to the pre-start position, then turn off once the motor is started (provided there are no codes)

I am helping out a guy elsewhere who bough a car with major issues, and turns out someone had disabled the CEL indicator.... dirtbags

A

Thanks for all of the replies. My CEL light works - it lights at start and then goes out. I'll start with the plugs and coil packs. I think I'll stick with the stock plugs for now. Plugs seem to be a subject like oil from what I can tell from these forums. If anyonenhas any strong objections to stocknplugs please let me know.

You CAN throw CEL's for misfires... Anyone want to put up money on this! ;)

To the OP it is probably plugs and coils needing to be replaced. How many miles are on the car?

I had a similar issue immediately after flashing my ECU.

Only once did it misfire enough to throw a CEL.

Going to cooler plugs solved it.

plugs and or coils.. classic symptom of stuttering at 4 to 5k...

Good to know. Both times I had issues with misfires, it was never enough to throw a light, yet changing plugs and coils fixed it.

I threw CEL's on misfires, but it never showed on my dash. I went in with durametric and there they were. I guess if you have enough misfires then you throw a check engine light. But if you don't have enough, you just throw internal CEL's that don't show on dash. Anyway that is how it happened to me. I changed O2's, coil packs and plugs, problem gone.

++++ for coils and plugs - Similar issues with a check engine light

this happend to me before after I got a flash. I just changed out the spark plugs and it was fine