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YOUR RESEARCH996 w/ 3 cylinders misfiring and secondary air system-bank 2 - CEL
Leading reported evidence
Replace few spark plugs here and there prior
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Performed · outcome unconfirmed · Original poster
The previous owner had changed a few spark plugs here and there prior to my owning the car.
996 w/ 3 cylinders misfiring and secondary air system-bank 2 - CEL
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Leading evidence: 'Replace few spark plugs here and there prior' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Check crystal ball' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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Suggestion
Metal shavings, but no bore scoring huh ???....So where did they come from ?/ <<< Checking my Crystal Ball ...
996 w/ 3 cylinders misfiring and secondary air system-bank 2 - CEL
Check exhaust really good
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Suggestion
Have him check the exhaust really good before ripping the engine apart.......would be ashamed to have a new engine and these shavings go into it ....
996 w/ 3 cylinders misfiring and secondary air system-bank 2 - CEL
Check power steering fluid level
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Suggestion
But it sounds to me like you should check your power steering fluid level which may be the "wurring" sound.
996 w/ 3 cylinders misfiring and secondary air system-bank 2 - CEL
Fill level
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996 w/ 3 cylinders misfiring and secondary air system-bank 2 - CEL
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Hi all.
Just got home from dinner and CEL came on and noticed a persistent rattle. Made it home the 1/2 mile and plugged in my scanner. Got misfires on cylinders 3, 4, 6, and a secondary air system code.
The rattle you can hear in the attached video. Seems to be coming from the drivers side exhaust area.
Anything come to mind?
The car has the IMS solution. 57k miles.
I am towing it in on Tuesday.
Thanks all.
edit: a mechanic friend hear the video and read the codes and believes timing chain tensioner.
edit 2: there seems to be a bit of excess soot on the drivers exhaust, also where I am hearing the rattle a bit more.
Do another video with longer production including RPM changes and possible load changes A/C on/off ect.....
What year is the model?
Could be just a loose Cat or Carbon on the Piston top ...
What does the oil pressure gauge say ??
You got to give us a little bit more to go on. New plugs? New coils? When? Any other maintenance? Generally speaking you can ignore SAI codes, for now. Not part of the troubleshooting loop on this one. Strange because 3 is on Bank 1 and 4 and 6 are on Bank 2.
Thank you. I am incredibly nervous about starting the engine again. I am concerned the IMS bearing, though a Solution, has failed.
It is a 2000 Carrera 4.
Thank you for replying.
I have not done a major ignition service. I was going to do it at 60k miles. The previous owner had changed a few spark plugs here and there prior to my owning the car. I bought it in 2020 with 43k miles (so added around 14k miles)
Before last night, I never had a misfire or throttled performance.
Recent maintenance:
<!--td {border: 1px solid #cccccc;}br {mso-data-placement:same-cell;}--> 8/22/25 Parking brake adjustment Werkstatt 57,087
3/29/25 Oil Change self 56,338
5/11/24 Replace loose wheel bolts House Automotive 55,238
5/2/24 Fuel filter Werkstatt 55,183
4/1/24 Oil Change self 54,994 129.02
2/12/24 r/r rear suspension with Bilstein B4
r/r rear sway bar drop links House Automotive 54, 857 1,451.62
1/18/24 Water pump Werkstatt 54,745 (note: Graf unit, with a metal impeller)
1/3/24 Mount/balance four tires West Coast Tire & Service 54,634 1441.54
12/31/23 Brake fluid exchange self
10/16/23 r/r castor control arms House Automotive 54,441 0
10/6/23 alignment
driver side VCG
rep fuel cap
r/r front suspension with Bilstein B4 House Automotive
5/17/23 Front differential fluid change Stuttgart 52,621 179.27
3/8/23 Oil Change Stuttgart 51,450 279.83
Here was one additional video I captured. The car had been sitting for a few hours at this point. The knocking seems to have abated. Might be some smoke from the left exhaust pipe?
WOW !! Shortest video's ever !!! ( 9 sec) .......I think next time I go to my Heart Dr, I'll give him 9 sec to evaluate my heart condition...lol
Seriously though, you need to take a Xanex , I don't think anything wrong with your IMS Solution, and the taping noise has subsided considerably giving more credibility to my loose Cat Hypothesis...
Does the rattling change proportionally with a change in engine RPM?
Is your exhaust system OEM or modified? And what is the secondary air injection trouble code?
here�s current sound and under a light load of around 3k rpm. Car is totally stock. I tapped on the exhaust system with a rubber hammer and do feel like there might be a rattle from the cats. Wondering if the harder knocking from before was a piece flapping that has come off. There�s a bit of white smoke at the end that I saw first time in this video. Air code is p1411
You Tube
Well we got 18 seconds on that video of engine sound and visual and I didn't see or hear anything unusual......so how long before it starts to make the unusual sound ? .........beginning to seem more and more like a big nothingburger ( Loose Cat ) ...
Troubleshooting is a process, sometimes a short process and sometimes a long process but always a process....
The "white smoke" is actually condensation from the start up. You really need to make a longer video (like a 1 minute or 2) if you want any input on your potential problem other wise just bring it to a mechanic. Hard to help with 9 second videos!
For sure a longer video would certainly help. Including getting closer to the engine to listen for different sounds. But it sounds to me like you should check your power steering fluid level which may be the "wurring" sound. But tough to diagnose from a video at a distance.
I wouldnt loose any sleep over the IMSB Solution.
But I will say that if you have old ignition coils, spark plugs, fuel injectors, o2 sensors, MAF and air filter, you would certainly benefit from replacing them. Its inevitable that they will go and throw cels. Why not do them all and eliminate the headaches.
@996love
is right. Change that water pump back to plastic fins and get in a rotation to change it every 4-5 years.
Plenty of other refresh items you can do if you want a list. Just ask.
For sure, an aging CAT can make some noises like you describe. I have one that is starting to go as well.
Best to ask as many questions as you can to get an understanding of things here on rennlist and get the car into an experienced Porsche specialist that knows the 996.
thank you so much! Yes; it will be fixed no matter what! Leak down test is happening right now. Hoping this is localized to the cylinders and we can do a top end tear down vs a full rebuild. But let�s see.
Seems like my original Hypothesis is still on the Table.....
Metal shavings, but no bore scoring huh ???....So where did they come from ?/ <<< Checking my Crystal Ball ...
If the Cats are falling apart ( like my original thought from the sound) ...the small pieces can float "up-stream" and go into the cylinder from a "reversion wave pulse" ......I have seen it before and also Rust from Rusty headers can float upstream and find a way to the cylinders...
I really can't see what your Tech is seeing ( pics are not clear/big enough for my old eyes) ...but with the Tech saying no bore scoring I believe him...
Have him check the exhaust really good before ripping the engine apart.......would be ashamed to have a new engine and these shavings go into it ....
"metal flakes in cylinders"..? with no cylinder/piston damage..? How do cylinders that look good have metal flakes...? I can't see it in your pics at all.
Only way I can think of, if its really metal flakes,, is from a dropped valve seat bouncing around on valve stem 'milling the head causing the flakes in cylinder..? But then there would be no compression at least on that dropped valve seat cylinder...
jmo
thank you will do!!
they did discover metal in the filter. They were *ahem* mistaken when the told me earlier there was no metal shaving in filter. They hadn�t really checked.
Uht-OH !! ...If true, this is bad, very very bad !!!!
What was your driving style before you noticed the noise ?? Were you running the snot out of it on some twisty roads ?? Oil type ? fill level ?? Miles on the Oil?
it was a very chill drive on the way home from Saturday evening dinner. I downshifted 3>2, perfect rev Match, not aggressive. Turned into my neighborhood. Oil level good. Liqui moly 5w40. Oil changed 4 months ago, maybe 1k miles on it.
Just this alone confuses me on the competency of the shop your car is in.
With a failed leak down test, maybe the biggest part of it is
where its leaking
. Thats part of the leak down report. That info should be in the reports next sentence for each individual cylinder. If he is telling you over the phone, should at the least say something like, "ya, heard it leaking out severely into the crankcase". Also, usually after a failed LD test, a follow up compression test is done.
A failed LD test without further explanation either shows the test was done by a inexperienced tech or for some reason purposely omitted/not disclosed.? I mean its not hard or time consuming to do... While the test is on going and leaking out,,, just remove the oil filler cap, air filter, and listen, also listen to the exhaust pipes. Its leaking out of 1 of those, or possibly all of them..? That info steers the tech to the problem area, which is what the test is for....
A severely failed Leak Down test, without the area of leak noted is like going in for a full body scan and the DR. telling you you've got a big ole tumor,, but stops there and omits where tumor is.
jmho
Yeah I'm not really buying the leak down test as the "cause of failure" either .....OP said he was just casually driving home from Dinner .....No overheating ect ...
I'm not saying the Shop is lying or botched the Leak Down Test ,,,but in my 50+ years of Analysis I can't think of a likely plausible scenario that would cause a LOT of damage all 6 cylinders without totally killing at least one cylinder....
