Porsche-Suchtig

I got the dreaded CEL/reduced power/multiple misfire codes last weekend at the track. Thinking the motor (original F series) had given up the ghost I packed up and went home. But when I got back home I found the codes were marked pending. So I decided to drive it this am before taking it in, thinking the codes would be stored after another drive. To my surprise, they just flat disappeared. And that was after about as spirited a drive as you can do on the street.

What’s up with that? Is it a ticking time bomb? Well we all know that’s the case since it’s an F series. But my dilemma is what to do now? Anyone else here have a similar incident with disappearing misfire codes?

Watson

Maybe the ignition coils only fail at high engine speed and engine load thus you don’t see the problem during normal driving.

Try to see if you can replicate the misfire codes consistently.

I’d start with the usual suspects for misfire aka ignition coils, sparkplugs.

Porsche-Suchtig

Thank you for the reply!

My first step is definitely to try to replicate it. And once I do the dealer will go down the path of coils, plugs etc before considering replacing the engine.

I am mainly curious if others have had the misfire codes disappear like this and how long it took before they reappeared and were saved (rather than registering as “pending” then disappearing).

I have expected the engine to eventually develop the FF issue. But what I didn’t expect was to be in limbo with the car and potentially wasting $1,000s on shortened track days only to limp home…. then have the codes disappear. But if that’s what others have experienced I’ll dig in for the long haul and just keep signing up for more track days until the inevitable happens.

Watson

I guess it’s possible that the misfire codes heal themselves if you don’t reproduce the misfire issue for enough mileage / time or if the misfire issue cannot be consistently reproduced in the life situation you described.

Be careful though when trying to reproduce the misfire at engine high speed and high load, if one of the spark plug is on the verge of being broken, that could lead to serious engine damage.

Porsche-Suchtig

Excellent point. I’ll make sure to check the plugs before the next track day. There were two cylinders with misfires but I think I’ll check them all just in case.

Jickel180

I would keep trying to replicate it on the street where you can. The key is to rev it above 8k rpms as much as possible and it should come back relatively quickly (in my experience). I'd be weary of booking another track day before getting the engine swapped.

SmokinGTS

When I lost a coil the car ran like crap at slow or fast speeds. I bet you have the -04 coils last digits. The latest coils which are much better end in -07 last digits. You may be lucky and hit the engine Lotto.

Porsche-Suchtig

I’m going to give it another go on the street. Today I did maybe 20 separate pulls with 2-3 shifts at wot. That allowed me to attempt to replicate it without going more than 5-10 over. But a friend who had his replaced in December said he found a place to do 3-4 shifts under load and that did the trick. I may have to resort to that. Idk.

Did your engine get replaced? I’m wondering if anyone else has had the disappearing code issue?

Porsche-Suchtig

That’s what I’m hoping. It’s a nice car but I don’t want to own an F series grenade after the engine warranty is up in a few years.

Porsche-Suchtig

A few things I forgot to mention is that I started feeling a little high rpm hesitation or possible miss at a December track day. It was a seat of the pants thing but I should see if any of it was caught by my aim data system.

I also noticed recently that when in pdk-sport/auto mode, the car shifts at 8750 every time. On the dot. I verified that with the aim data too. The only way it will rev to 9k is if I shift manually.

One last oddity, today I noticed that it will only rev above 8,500 for a fraction of a second. If you try to hold it at say 8,600 (or above) the computer seems to retard the ignition and force you back to 8,500. No matter how hard you press the throttle, once this happens, it won’t go over 8,500 without first letting the revs dip quite a bit (maybe 1,000 or so) then accelerating again.