IAC Problems, clogged ports in head 2006 Boxster S

I have 146000 kilometres on my Boxster and last few season noticed a small oily drip from the Exhaust manifold gasket on bank #1. I have checked the bolts and all seem snug .I found it getting worse this year so I decided to pull the exhaust manifold on that side only. By the way I have had no check engine lights but have noticed a light ticking (not injectors) coming from that side of motor that gradually goes away after warm up. After pulling the manifold I noticed that the air ports in head and the machined out valley on the head were approx 70% filled or clogged with a black tary goo and not dried carbon like I have seen on some pics on 986 boxsters with really high mileage. While I was in there I pulled the plugs and all looked ok, light brown on the firing tips ,no oil on tips but one plug had quit bit more oil on the threads than the other 2 . After closer inspection on all components I found the coil on that plug to be cracked, others were ok ,coils are original and plugs I did at 80000 Kilometres. I also noticed that the manifold was warped slightly .I ran it across a strait edge file until flat and even,dident need to take much off, reinstalled everything with new gaskets and no leaks after 2 tanks. Also Ticking noise on cold start-up gone! My concern it why the tar not carbon and small oil droplets leaking out. Is that a sign of bore scoring, rings,exhaust valve guides/seals or possibly keeping the oil level to full which I found out by my Indy not to do.I dont mean over full but on the full mark.He told me to keep level at middle because of the emission system, Note I have never blown an AOS. Have always changed out well before they go. I emailed LN and he states bore scoring, I have not scoped cylinders yet but dont use excessive amounts of oil, maybe 1.5 Litres every 8000 Kilometres (5000 miles) and no excessive carbon on tail pipes or oil splatter on rear bumper. Alough maybe im getting to the point that I may start seeing that if oil droplets were increasing on the manifold.

It's interesting that LN Engineering would conclude that it is bore scoring. According to Jake Raby's video series on bore scoring, the M96 3.2l Boxster engines are least likey to have bore scoring issues. Also, bank 2 (cyl. 4-6) is more likely to exhibit bore scoring. Your oil consumption seems to be well within Porsche 's oil consumption specification. If you are really worried, I suggest you get an oil analysis when you change your oil next to establish a baseline and also have subsequent oil changes analyzed for abnormal changes. For additional peace of mind, you could also run a compression test to see if there are any weak cylinders. -RobT Sent from my Pixel 3 using Tapatalk

Thx for reply Rob, I ordered a sample bottle for oil analysis . Conflicting info on Black Stone vs others. Apparently LN recommends another company as they are able to tell u weather the piston or cylinder coating is in the oil and the amount, Not sure what that coating is buts that basically what I need to know I guess

I would start with the oil in the air ports in the head and machined valley filled with tar. Is there one port that has the tar/oil or all three? The machine valley might be collecting the oil somehow. Now sure but I saw another thread where the guy's head evacuation pump was not working properly, causing a lot of oil to accumulate in that head. He thought is maybe an AOS issue, so he changed that part, but then figured out it was the head pump. Not sure this had much to do with your tar, but that tar got there somehow. Is that one cylinder burning a lot of oil? Enough to cause the tar?

The tar might also be a result of the exhaust gasket leak between the exhaust ports and the EGR ports. This may also explain the ticking noise that went away after the exhaust header gasket was replaced. -RobT Sent from my Pixel 3 using Tapatalk

Thx Guys, Im stumped and so is my Indy that I just came from.Unfortunately it all buttoned up again so he could not see what was going on. He stated that usually its just a buildup of carbon in the valley and ports that after a while (many miles) will clog and u will get a a check engine re emissions . But I have none YET ,he ran a diagnostic and all good. He stated that if I did have some bore scoring then possibly oil in cylinders and would show in the exhaust port. I wish I had taken some pics but I do recall the centre cylinder exhaust port having a good build up of carbon around the opening or port. The Tary stuff seemed to be mostly in the air ports and channel. My AOS is good, changed approx 40 k (Kilometres ago) I also cleaned out the intakes at that time ,they weren't terrible.Never had Maf problems and air filter was pretty clean.He asked if the plug tips were oily but they all six were light brown and dry on the tips.RobT I was thinking along the same lines with the warped head pipe flange and leaking gasket possibly causing the Tar.But the Ticking start up is definitely gone and no more leaks at that point. after 2000 Kilometres! Have used maybe 1 cup of oil. Apex I was interested if the post u referred to regarding a defective air pump causing a similar issue. Would that not give a check engine? Maybe its intermittent . I personally cant hear any pump when starting, maybe I need to remove the engine cover .Indy showed me wear it resides on a motor on the bench out of an 04 with u guessed it IMS bearing failure.

Where does the air pump get the air to feed these ports? It would be worth a look at what's going in.

The head pump is a vacuum pump that sucks out the oil and mixture of oil/air into the sump. M96 and M97 engines have two of these pumps at opposite ends of the head. One per bank/head. The newer engine 9A1 has 4 of these pumps, so you can see there was/is a need to help suck out of the heads the mixture of oil/air. The reference PDX was a boxster that had one of these two pumps fail. So that head was way too full of oil. The oil actually started to be sucked into the AOS, to a point of blowing up the AOS. When the owner took of the head vacuum line that goes to the AOS, it was completely full of oil. The other way to look at this is to button up the engine and just look at the oil usage. Change the oil every 4000 miles. Unless you get a really good recommendation of a Porsche mechanic that really knows about these issues. Then let him have your car for a couple of days to research this issue.

What do the scavenge oil pumps have to do with the air injection pump? Oil going into the cylinders from flooded heads, bore scoring or the AOS is likely going to exit the cylinders as coke (carbon). Not having oiled plugs tends to rule out this also. Liquid oil pumped into the air injection ports by the air pump would likely be caramelized and cooked down into the black tary goo described. Since nothing else is being found it might be worth a look at where the air pump is getting the air. I just don't recall whether that's the engine bay or the engine intake.

The oil from the head where the scavenge pump is deficient would seep down the valve guide, could happen even after shut down if enough oil is left in the head under slight pressure. I would think you would have oil smoke on startup though? lesmurry had to rebuild his engine from a valve guide issue. Maybe he has a clearer picture as he did this. His was not caused by a scavenge pump though. The air induction system only works for about a minute to help light the cats. Not sure if that system would cause this issue as it would create smoke through the cats as they light up almost like a failed AOS would.

Mine was burning oil and upon breakdown we saw burned pistons in #5 and #6. Cylinder walls were clean and no issues in the bottom end. So we had valve guides going bad.

Update: My Indy thinks that my problem is I have always kept my oil level at the very top setting. He suggested that I never have it higher than 1/2 way on the electronic dash readout. Please also note that Jake Raby clearly states in one of his tube videos to do exactly the same . I think that many that have higher mileage will start noticing issues with codes that when looked into find that the ports/valleys will be clogged in the heads and need cleaning. I hav not had any codes on my car other than a gas cap seal issue that I solved. Once the ports are completely clogged it will trigger a code and they will have to be cleaned out. This can be a real pain as the header pipe bolts can seize in the heads and pull threads.One of mine stripped slightly when removing. I installed new bolts, cleaned and ran a tap thru, seems to be ok so far after a few thousand miles. A torch is a necessary tool to get this pipe apart also. The hardware will be rotted and need replaced FYI. Thx for feedback, great info APEX 1.

That is a simple fix to a complex issue. For us track guys, especially with deeps sumps, x-51 baffles and windage tray on top, its mandatory to run 1/2 full on the gauge due to oil sloshing up the side wall into the AOS. After replacing the AOS a few times, you learn that a full sump is not the best idea. Porsche makes a motorsports version AOS that can withstand more oil abuse, but will still fail after a number of oiling doses. That one really hurts the pocketbook.