996.2 C4S - Sudden P0011 + P0303 - Shop wants to pull heads?

Hi everyone, I wanted to share a recent technical adventure with my 996.2 C4S (3.6L M96.03, 230,000 km) and get the community�s brainpower on this. The car has a what I believe it is a factory-sealed engine and has recently been running on 10W60 oil (recommended by my local independent Porsche specialist). The Context & Symptoms: I am already planning to have the engine fully rebuilt very soon, as it is starting to show the classic signs of bore scoring (the left exhaust pipe is notably sootier/blacker than the right one). Along with the bore scoring signs, the AOS seems to be slowly dying as well. My goal was simply to keep driving it gently and at least be able to drive the car myself to the shop for the rebuild. Instead, the car completely gave up on me. I started it up, drove for about 4 km and right as the engine was warming up, the Check Engine light popped up. Instantly, the engine started misfiring heavily, shaking, and developed a very rough, unstable idle. It feels like total immobilization now. I had it flatbedded to my local Indy Porsche shop here in Luxembourg. Before dropping it off, I checked the codes and pulled the cylinder 3 spark plug: Codes: P0011 (Camshaft Position Bank 1 - Below Limit) and P0303 (Misfire Cylinder 3). Spark plug 3: It was pitch black, ugly, and heavily smelling of raw fuel. The Shop Diagnostic: From what I understood from our phone conversation, the mechanic performed a physical compression test through the spark plug hole on cylinder 3 and reported bad compression . They also used a bores por inside cylinder 3 and told me that the valves do not seem to be closing properly . Because of this, the shop is now strongly recommending to remove the cylinder heads to investigate a potential broken valve spring or bent valve. I strictly refused the teardown because paying for heavy labor to open the engine right before a complete rebuild makes no financial sense. I am flatbedding the car back to my garage. My questions : I tend to rule out the P0011 VarioCam phaser itself as the direct cause for the open valves, because a blocked solenoid would trigger misfires across the entire Bank 1, whereas my misfire is strictly isolated to Cylinder 3 (P0303). Do you agree with this logic? Could mileage or the thick 10W60 oil have caused an isolated stuck lifter or a broken valve spring on Cylinder 3 only ? Do you agree that pulling the heads now is a complete waste of money since the entire engine will be stripped down to bare metal very soon anyway? I�m pretty gutted that I can�t even drive it to its final destination for the rebuild, but I'm looking forward to your technical insights while the car sits in my garage.

I agree, makes no sense to remove heads and not do a full rebuild. Heads can remain bolted to the engine when removing cams and lifters to check for broken valve springs, stuck lifters, bad cam solenoid and bent valves. It could even be done with engine in car, although most will prefer to drop the engine. At 230' km exhaust valve guides will be worn and cilinders out of round, so if you want to keep the car another 10y or more , rebuild now.

Quotes source post: 20686051

Hi! Thanks for the answer! Fully agree. A complete rebuild is already the plan since I want to keep the car long-term, I just didn�t expect to be forced into it by a single valve issue right now. I wanted to finish the season and drive it to the shop myself. Could you share more details on the method of removing the cams and lifters with the heads still bolted on? I would like to ask my garage if they can perform this "band-aid" intervention just to get me through the next let�s say 3,000 km.

I had a customer car that lost compression on one cylinder and it was a broken valve spring. It was a 5 chain motor, but that doesn't really matter, the head did not have to come off to repair it. Story here: https://rennlist.com/forums/996-foru...ht=compression Best of luck

I don't think you can properly time and tighten the intake cam on bank 1 (Variocam Plus) with the engine in the car.

Contact Hartech for a top-tier superior rebuild. Perhaps even go to a 4.1L increase. The Hartech system fixes all of the known P-warts and failure points. They have different pricing method, low cost, then add everything done as a final bill. I have no idea what the UK/EU cost is. A C4S with a 4.1L "basic" build will be around 390 HP (+/-) and very durable. It also comes with a warranty, a nice feature. If you can't get the car to Hartech, take the engine out and strap it to a pallet and ship it to Hartech. At least, those are options here in US. Whatever, your choicesl learn about it and decide. YMMV

Thank you all for your contributions to this thread! A special shout-out to Paul�your link and the breakdown of how you handled your client�s car were immensely valuable. It really helped me understand exactly what I�m dealing with here. Since all of your advice is pointing in one clear direction: rebuild it is! I�m definitely going down that road.

I should also add - a C4S is "one" of the more rare or valuable 996 Carreras. P only made about 17000 of them and you DO get a lot of the "Turbo" goodies: better suspension, Litronic lights, leather interior, bigger brakes, larger radiators, Fat-Azz rear fenders with wider wheels (gorgeous) and so on. It is "Worth IT" in my opinion to rebuild the Hartech way, more power and torque, none of the failure points missed, and a stronger long-life engine. The Hartech system also reprograms ECU + etc to make engine work at far higher levels than OEM -P. They test EVERYTHING, injectors, valves, cams, coil packs, starter, alternator, replace WP with LTT, and whatever else they find (like almost to fail coolant hoses), and more. Dyno charts + HP/TQ results, blowby proving engine a "broken in" by Hartech, and many many more quality tests. A 996 3.6 Vario+ engine isn't cheap, and Hartech (Slakker=USA) can make it even better than OEM. Sure, it costs more. My C4S is my "forever car", I don't regret the cost (well, most of the time), but it is almost done. A basic ordinary 4.1L rebuild, 390 Hp-355 TQ works for me. Add the other things like 8K rpm, Intakes, exhaust stuff (more $$$) and you are in 996TT Turbo territory without a turbo and those associated problems. But, do you want a cheapo fix that may last a few years or more, who knows? Hartech cost is a reflection of what they do to assemble everything so it will last another 100k miles ( 161k Kilometers) no question. Just because you bought a "depreciated low cost - compared to new $$" C4S does not mean it is a cheap car like a Toyota or common refrigerator. JMO. YMMV

You mean they make "only" 17,000 C4S ??

Quotes source post: 20689095

Sorry, I had to go look up the chart someone made - it was 23,055 996 C4S made in 3 years. About 1/2 of that number were cabriolets. So yes, C4S cars are semi-rare. Here is a chart another RL member made: