New Porsche owner questions

Questions from a one-week-old Porsche owner: 2004 Porsche 911 Carrera Cabriolet with 53K miles. Bought from a dealership in Denver and shipped to Nebraska. Car is super clean and well maintained throughout its life at a Jaguar dealership in Denver. I have searched this website for answers but only get confused in my search. 1. When starting the Porsche after sitting over night or 1-2 days, it smokes at startup. My research tells me that is normal if smoking quits, no noticeable oil consumption. 2. On the second day of ownership the check engine light came on and stayed on. Code P0420, Catalyst System Efficiency Threshold (Bank 1). Looking at using a bottle of Cataclean to clean the cat and/or O2 sensors. Calls to add the contents on a quarter fill gas tank. (Figures, I filled it up the day before with 91 Octane gas and now must wait until the � tank) After adding contents, drive about 20 miles, refill gas tank and hope the check engine light goes off. 3. If the light doesn�t go out, any suggestions? Cat replacement first or O2 sensors? No noticeable issues are noted when driving. Good pick up and appears good gas mileage. Looking for suggestions from you, my knowledge base. Thanks in advance.

Quotes source post: 19805836

Nebraska is a non-inspection state. Hypnotically you could get soul or fabspeed cat bypass pipes with some o2 sensor mini cats and never worry about it again.

Thanks Arione. That's always and option but would like to keep it original as much as possible. Understand why some use non-OEM parts because of the expense of Porsche parts.

I can't help with the Cat questions, but I can say my 104k cab and my 76k coupe (both 1999s) never smoke at start up, even after sitting for while. The coupe I've only just got, so I haven't yet pushed the engine, but the cab I drive at very high RPMs when driven. From what i've read, the smoking can be due to just excess oil - but I wonder if you spend a week pushing the car at redline if you notice LESS smoking after those drives. Also, from what I've read, these engines really like to pushed (obviously in normal limits) and keeping them running at high rev also cleans up some seal oil leaks (mine dripped a bit when i first got it, it has never dripped again in two years).

Thanks for the reply Ben8jam. If anything, I most likely drive my Porsche at a lower RPM than most of you folks do. I don't ever get into the 5K+ RPM range. Today I took it out on the interstate to get it in a much higher speed and blow some of the carbon out of it.... if it had any to blow out. Again, using most of the gas to get to that magical quarter tank to try out the Cataclean method. Trying to pre-position myself on my next move it the Cataclean doesn't work.

Quotes source post: 19805913

Going 100mph at 4k is not any different than going 20mph at 4k. Your car will thank you if you hit that limiter every once and a while. When I had my "post"-purchase inspection, my Porsche-only indy mechanic saw a small RMS leak and suggested first thing to try was to see how it was after a few months of driving it like it was intended. Sure enough, it's never leaked again. I'll leave it at that, you'll probably soon see, there are a lot of opinions on here

Daliab, try Google search 996 P0420 code and you will see a bunch of Rennlist discussions. Quick read says it could be fuel getting not burned well, so replace coils and plugs. Others pointed to the AOS. Smart answer based on cost would be to replace the O2 sensors before the cats if that is the option. Curious, did you get any service records with the car or Carfax? When you say it smokes on startup, is it really smoke or steam? In other words, can you smell it? So you bought it from a Jag dealer? Surely they got the same code and reset it before anyone test drove it?

996-CAB, a lengthy clean carfax was included with the car and was taken to a Denver Jaguar dealership for regular service from the day it was purchased. From the looks of the car, it was never abused and well maintained except for the existing tires that were 11 years old and showed cracks in the sidewall but still had enough tread to pass inspection. No drips or leaks from my untrained inspection and the motor was clean as a whistle. As for a dealership clearing the code before the sale, that has crossed my mind. You never know. This Porsche has 19" rims, and I just put on 4 Continental Extreme Contact DWS06 Plus tires (285x35 R19 99Y SL BSW, and 235/35 R19 91Y XL). The blueish white smoke only comes out after the car has been sitting for a long period of time and only does it initially and goes away after less than 30 seconds and yes it does have a slight smell. Hoping the Cataclean works before I end up chasing the problem by shot gunning parts on the car.

Dunno if this would be an issue at cold start - but consider whether bad O2 sensor or exhaust leak at flange is causing both the code and smoke due to over-enrichment.

There are good Porsche dealers in Denver, the Jag dealer part makes me suspicious. Did you get a ppi? The smoking part concerns me. Keep a close eye on that. Do a lot of reading on AOS system. Smoking is an indicator of that going bad. And please listen to others when they say to run up the RPM's on a regular basis. Not going to hurt it. Might want to find a specialist in your area and please please don't let it go to a Jag dealer again!

Quotes source post: 19805997

There are better people than me on this site, but your blueish white smoke would be oil. The oil messes up the o2 sensors. I suspect you have an AOS that is failing. This can be replaced wiithout removing the engine. If you decide on this, consider an ultimate AOS or UAOS which would prevent this issue from recurring. You can Google search UAOS. Many of us have made this change, me too. A failing AOS is a known issue of the 996, but UAOS solves it. If not repaired, your engine could ingest enough oil to destroy it. Should have mentioned, please check your oil level and make sure it isn't too high.

Quotes source post: 19806096

+1 to that. Non-Porsche shops/mechanics don't realize the oil level is supposed to be midway. Not full. Full=overfull.

As far as you're 420 code, I've been getting the equivalent (430) code for my other CAT. This is since I've bought the car in 2021. I know for a fact it's the CAT that's bad so I've been using an OBD2 scanner to delete the code when it comes up once in a while before I actually commit to replacing them. I'll echo the message here to drive the car the way it was meant to. Stay below 3k RPM while warming up the engine (never at idle, drive off a few seconds after startup ALWAYS) and once the oil is at temp (check oil pressure, not the water temp gauge; should be <2 BAR at idle when fully warm) I drive above 3k RPM with trips to the red line throughout.

Quotes source post: 19805856

its a 996, aftermarket headers wont effect the value at all. It'll actually protect the car as you wont have to deal with catalyst failure. agree with opinion that speed itself wont blow the carbon out, gonna need several 1st to 4th redlines in quick succession to heat everything up hot enough. needs high rpm, not high spedometer

Quotes source post: 19805856

Welcome to the 996 club. It's a great car and very easy to take care of. As a comment to your point on why some would use non-oem parts because of the expense of Porsche parts, I would say that this isn't the entire story. The reality is that some Porsche parts are just not adequately engineered, and after 25 years of the M96 being around the Porsche community, owners and the industry have figured out that there are better parts that have been developed that are more durable and more expansive in what they solve for versus the limitations and frailty of specific factory parts. Case in point would be the IMSB and AOS. No reason to fear upgrading a part. Your resale value will thank you. Regarding your smoking. Without seeing your car, service records or knowing anything about its history, there is a still a pretty good chance that the smoke is being caused by either... (1) a failing AOS, or (2) common problems associated with the factory AOS even if it's not failing due to the factory AOS being a poorly designed part that is unable to properly process "full" and "near full" oil levels in the engine. Same can be said if you park the car on a hill, drive on a hill, or take it thru a couple of curves in the road. The oily smoke then blows out the exhaust dumping it in your cats, creating problems with your oxy sensors. First upgrade you may want to consider after testing your AOS for failure with a manometer for your own edification, is to replace your factory AOS with the UAOS. Another upgrade you may want to consider instead of spending big bucks for a new set of cats is to get oxy sensor extenders on your cats. This moves the oxy sensor further away from the exhaust flow and helps to reduce the number of cels. Many of us do this. Third thing to consider is refresh specific factory parts that are old with new factory parts that will help the engine run more efficiently. These include: factory water pump, plugs and ignition coils, MAF, fuel injectors and oxy sensors. Dont forget to run great oil and change it 2x a year. If you are going to put something in your fuel to clean the engine, stick with techron or redline. Plenty of threads on the info. Lastly, let the car first get up to temp, then dont be afraid to drive it like you mean it. It loves to be pushed thru the rpm range. Good luck with the 996. its worth it.

Quotes source post: 19805913

A few folks have mentioned this already, but...why? Why don't you ever get into the 5K+ range? If anything, consistent lower revs in this engine are more of a detriment than anything. 5 - 6K isn't even pushing it in these, and the engine was quite literally built for that kind of ***t. Wind it out, have some fun.

Quotes source post: 19805913

Here is another way to think about it. An internal combustion engine develops increasing horsepower and torque with RPM. It's just the physics of sucking in more and more petrol in a given second. When you drive your car at low RPM, you are putting a large load on the engine. You may have 100 HP at low RPM but more than double that at 4000 RPM. The car's engine can move your car around much easily if it is generating more power than it can at lower RPM. The extra power it develops means it is lower strain on the engine when you are over 3200 RPM. Personally, the only time mine is under 4000 is if I am stopped or getting there from stopped position. If you have the owner's manual, in the back there is a chart that shows the power vs RPM curve so you can see how it works.

I got the PO420 2X and 2/2 times the cat had failed with the element coming free in the tubing.

Welcome to the fun!! Seriously, as many have stated, run her like you 'almost' stole her! The best advice a Porsche race shop told me shortly after I bought mine was do not baby it, I'll do more harm. coming from superbikes (Yamaha R1) I know what that means: MORE SMILES! Good luck sorting it out.

First, thanks for everyones thoughts on my CEL and smoke at startup issue. Good news, no more smoke at startup for the last couple of days. I did check the oil level and thought it was good until someone stated that oil at the full mark is really to full. I'll have to monitor this. Took the porsche out to use up some gas to prep the car for the cataclean treatment. Running the car at a higher rpm than normal from suggestions. I also cleared the code to see if it was the startup smoke the triggered the CEL.... Grabbing at straws here. Car runs great! Lots of pep, no misfires, no smoking while driving, or anything that would give an indication of something is amiss. Fingers crossed that the code doesn't return.

Quotes source post: 19807134

" Lastly, let the car first get up to temp, then dont be afraid to drive it like you mean it. It loves to be pushed thru the rpm range" Just to clarify this comment, it is well documented that it is very bad to let the car "warm up" at idle when first started. What you should do is start it, make sure you have oil pressure, and drive it right away but keep it under 3K RPM until it comes up to temp on the coolant gauge. Sage advice.

Quotes source post: 19807990

Agreed. "Up to temp" does not mean to let the car idle in the driveway until it's warmed up. It means start it and drive it immediately while keeping RPMs under 3k until its up to temp. Then drive it like you mean it. See attached link below to @Coopduc Digital Oil Temp Gauge. Very handy tool for those that want to measure oil temps in their 996. https://rennlist.com/forums/996-foru...emp-gauge.html

Quotes source post: 19807691

Never heard of Cataclean. What is it exactly? Fwiw, as I mentioned a few posts back, you may want to consider using Techron, Redline or Driven products instead to clean your M96. They have been thru the gauntlet and back again as it pertains to the M96.

Quotes source post: 19808086

Carbon build-up is a natural by-product of combustion and it can cause problems in vehicles, which can result in unnecessary downtime and worse performance. Cataclean can prevent this. Added to the fuel tank, Cataclean does not alter the fuel composition, Cataclean is carried with the fuel through the fuel system, cleaning carbon build-up as it comes into contact with it. Cataclean�s cleaning formulation can clean everything the fuel comes into contact with including the fuel injectors, cylinder heads, intake valves and oxygen sensors. Upon combustion in the combustion chamber, Cataclean creates an acidic vapor containing carboxylic acids that continues through the system to clean carbon from the exhaust including the catalytic converter and DPF/PPF. Ensuring the fuel and exhaust system is clean can produce benefits such as reduced emissions, restored performance, and improved fuel economy. A cleaner fuel and exhaust system can also prolong the life of vehicle components.

Quotes source post: 19808107

FWIW, I would stick with what's safely and effectively already been tested and used in our M96. Redline Complete Fuel System Cleaner Techron Complete Fuel System Cleaner Driven Injector Defender Good video from PCA and Lake Speed. Long but useful. https://youtu.be/CvkK-dShtM0?si=puiHyNS_0IlEbB96

Quotes source post: 19807351

Three letters. MPG. I know because I'm guilty of this too. While I do enjoy giving cars gas every now and then, my responsible, practical and frugal adult side is more often in charge. OP 's first post was a give away, talks about consumption...

Yeah, I wouldn't drive any M96 powered 996 at low RPMs to improve gas mileage. The M96 engine wasn't designed for that type of stress. Instead, I would buy a hybrid. Good R&T article link below on best hybrids for MPG. The more effective course of action would be to improve the gas mileage of the 996 through the entire powerband by refreshing specific parts that all tie into the air/fuel/computer system. For sure, it's gonna cost a couple of bucks which no one likes, but the m96 will run better and more efficiently, get better gas mileage, and your engine bores will thank you because you are giving them a chance to survive a much longer life. 1. Replace OEM AOS with UAOS - To mitigate oil blowing thru the system and out the exhaust causing adverse consequences to your cats and oxy sensors. Your cats will thank you, your oxy sensors will thank you, your air/fuel/computer system will thank you, and your bores will thank you. Factory AOS is the weak link. 2. Refresh fuel injectors, plugs, coils, MAF, oxy sensors, engine air filter, all of which will help with the air/fuel decisions of the computer and improve gas mileage, not to mention your bores will thank you for mitigating excessive levels of fuel into the cylinders which not only hurts gas mileage but also dilutes oil lubrication and hurts the bores. 3. Run high quality oil and keep it fresh with changing it twice a year. You want the oil to maintain its highest form of lubrication. Your engine internals will thank you. Especially your bores. 4. Follow the proper start-up procedures and DO TAKE the engine thru the rev range after its up to temp. Your engine will thank you. https://www.roadandtrack.com/ranking...xoCvQ0QAvD_BwE

So will your wallet.

Quotes source post: 19808065

I also doesn't mean when the coolant gauge is up, we're taking oil temp, which can take longer to get to temp than the water. Right?

Quotes source post: 19810572

Sure, oil takes longer than coolant to get to temp. But once oil is hot, and you put the car thru its paces, oil temps will move faster than water temps. Not to mention they will go down slower as well. Below is a picture of my instrument panel with @Coopduc oil gauge on the bottom right. Just pulled into my garage after an hour or two drive on local roads and the highway this past summer. Oil temp 211. Water temp ~190-200. Very helpful gauge.

Update with p0420 code. Use Cataclean via i structions. Added contents of battle of !/4 tank and drove 20-30 mile on the.. highway with 4k RPM +. After driving 20-30 mph and cleared the CEL. Drove a tank full and traveled 250 miles without the return of the CEL. In addition no random 30 second smoke at start up. Will continue to provide updates.

Hey man. Saw your post on the other thread. You may want to re-read your thread. Most importantly, the M96 is an engine that you should have serviced by a Porsche Indy that knows what they are doing. You do what you feel is best, but i hate to see a good guy go into a Mercedes shop and expect them to know all about the M96 and what to look for and how to do it. It like asking a cardiologist to perform neurosurgery. Yeah, they are both doctors, but different areas of specialty. There has gotta be a good Porsche specialist shop somewhere near you. Best thing you can do is go to LN Engineerings website and buy the speednogstics 3 day turnaround oil test kit that invludes the pump. Best money you will ever spend. In 3 days you will get your oil analysis and it will give you indications on what may be going on. Most importantly dont loose any sleep. A bad AOS can create lots of the issues you are concerned about. Easy to solve for.

My Porsche Update: Pros: Runs great. No misfires. No performance issues. Not smoking like it use to. Believe the issue mostly contributed to filling oil to full mark. Many writeups state only to fill halfway up... seems to be better. Running at a lower RPM seam to slow down my oil consumption issue. Cons: Still getting P0420 codes even though I clear them. Checked for bore scoring - Yep. Cylinder 3 - some, Cylinder 5 more, Cylinder even more. Did not replace AOS because of the bore scoring confirmation. Parts Replaced: Replaced spark plugs. replaced O2 Sensor bank1/downstream. See screenshot of scanner. Any suggestions? I'm seeing bad cat..

Quotes source post: 20046587

Two things. 1. Watch Jake Rabys Youtube videos (rennvision) on bore scoring so you can implement the proper procedures to prolong the life of your bores. 2. Find @Porschetech3 UAOS thread and read all about the AOS and then consider getting the UAOS w/ Track drain even if you aren't going to track your car. You will never have to worry about exhaust smoke from a failed AOS nor worry about overfilling your oil again. Its a no brainer.