2 part question

So this morning when i got to work i got a CEL. Stopped at advance to borrow there code reader and got P1124 and P1126. Did some research and found its due to an air leak somewhere and usually due to the AOS being faulty. So i decided to go the smart way (cheap way) and pulled out the air filter and MAF sensor. cleaned both and during reassembly tightened resented the hoses and tightened the clamps up to the throttle body. It seems to have cleared the codes for now. Question 1: Should i think about replacing the AOS to be safe? it just seems like a decent sized undertaking to get to and would rather not if i dont have to. is there anything else i should look at besides the AOS if it comes back. Question 2: turns out the previous owner put a K&N air filter in. Do i need to oil it when i clean it, or will just cleaning it out be fine?

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Replace with OEM paper filter.

Googling it shows this from the Boxster forum P1124 Porsche fault code - 167 Fuel pump relay final stage and... P1126 Porsche fault code - 356 O2 sensing adaption lower load range bank 1 Which was suggested the MAF issue. I'm not sure why a AOS would cause MAF issues, those get dirty and a MAF cleaner can fix it...or replace the MAF sensor, it could be broken or have issues. Just my .02 on the codes. I believe AOS has other symptoms like smoke and such it probably isn't that. Although they do fail, it might not be a bad thing to replace.

yea i was going off of what the recommendations from this thread. https://rennlist.com/forums/boxster-...ult-codes.html Is the OEM filter actually better than the K&N?

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Yes the OEM is much better and disposable. OEM vs reusable "performance filters" is widely debated. OEM is the way to go because the K&N can foul the MAF with oil which by the sounds of it, it has... Replace with OEM paper filter, clean MAF with specific cleaner see if the errors come back. Not too sure about the fuel pump error though.

Before those codes came up, did you notice any fluctuation of the revs at idle? Or maybe a slow return to normal idle after stopping? The reason I ask is I have the same codes which I have been trying to solve for a few months now. My latest find (apart from those I mention) is a split lower rubber boot on the AOS plus a single metal strand broken on the accelerator cable (I have the cable operated throttle, not egas) close up to the throttle attachment. The strand catches up on the return to normal idle. My new cable arrives next week from Pelican Parts. Hopefully this will solve my 1124 and 1126 codes once and for all. An INDI changed my AOS about 6 months ago or at least he said he did (but how come I found a split in the rubber boot?????). I thought the lower boot came along with a new AOS. The boot I found is certainly no where near a new one.

Yea the idle after coming to a stop will sometimes go a little low and then overshoot a bit before settling at normal. The CEL returned on my trip home from work today so i will probably be replacing the Air Oil Separator next in my search for the cause. I also have a 99 so the mechanical linkage throttle but haven't noticed any fraying. P1124 Oxygen Sensing Adaptation Area 1 (Cylinders 1 - 3) - Rich Threshold P1126 Oxygen Sensing Adaptation Area 1 (Cylinders 4 - 6) - Rich Threshold But according to pelican parts tech forum those are the correct meanings for the 996 and 986. so both banks are running rich.

Durametric will tell you what is happening to the fuel trims when the O2 sensors are running out of adjustment. Certainly looks like they are 'trying' to compensate for an un-metered air leak.The leak is at a location common to both Banks. Should be easy to find with propane or smoke?Lots in Search

"Better" is relative. If you NEED to get more air into an engine (say, newly turbocharged), you use the highest CFM unit that still has acceptable filtration...and the cone filters do a great job of packing a lot of filter into tight spaces. But for stock 996's, a cone filter improves performance about as much as a genital piercing (i.e. not nearly as much as you were hoping)...

The previous owner didn't replace the entire intake assembly just the filter so its not the cone style. just the normal 996 style just a K&N brand non paper filter. Thats probably why it went so long before i noticed it wasn't a stock filter.

Here's the boring answer, then...look up the K&N part number and see if it filters better than the OEM paper filter. If it IS better, THEN decide if the hassle of the (very) occasional cleaning and recharging, plus the good chance of blowing at least one MAF (if you over-oil, and it seems like everyone over-oils), outweigh whatever benefits it has over the paper filter.

Ive had K&N filters in almost every car ive owned since the 80s Never any problem. If that filter would have caused a problem it should have happened Years? ago. if you want to clean it, use hose and squirt pressure thru it, you can spray it with any fantastic or simple green, and wash it untill its clean. Put it out on the drive and let it dry for a day or so. You can blow it with air, etc. If you want to reoil it, (dont have to), spray it lightly with Pam

If your idle is dropping below 800 rpm on return to idle might be worth cleaning the idle control valve on the side of the throttle body it's common for it to stick, remove it and check it with a 12v battery, it should flick across fast when you touch it to the battery ( use some wires to connect to battery and just quickly touch on control valve terminals, If it doesn't move spray it with carb cleaner and leave to soak for a while then try again with battery till it moves, resist the urge to loosen it with something as the little metal flap is quite thin and bends easily as I found out !!

Hurdi Yes you get the boot also, I put a new one on my engine when I did my build , unless it's an aftermarket one and he re used the original boot which is bad as they are known to fail with age, this could be effecting your idle as losing crankcase pressure can cause idle problems, I had a split oil filler tube which gave me problems also, I'd try to seal it , at least temporarily just to see if it solves things for you, if you can get to it, there's a type of scotch tape we use in the cabling industry it's sort of stretchy rubber, sticks to itself as you wrap it if there's enough Room, would seal good, I think there's similar at diy store called plumbers tape?

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did you just suggest oiling an air filter with cooking oil?

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I believe he did...Perhaps on a hot summer day, you could throw some Orville Redenbachers in there...By the time you get to your destination...you know the rest. Just be sure to use the butter flavored Pam

^^^^^ could be the hot set up

I believe that in the event of a true emergency, a Red Vine can be inserted into the MAF sensor housing. Unlike the actual MAF, Red Vines are not directional.

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Hill-Billy Mechanics!

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This is for the non eGas throttle bodys correct? and as for the cooking oil for the air filter ill hold off on that for now.

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Cooking oil on an air filter is a big no-no. Use an oil specifically made for air filters. Air filter oil is VERY tacky and is designed to trap particles. Cooking oil is design so things don't stick. But if you are going to use the cooking oil tip, I might suggest crisco/canola oil mix at 25/75% ratio for your motor oil. You'll have to heat the crisco before you mix them though

Quotes source post: 14056082

I've not used oiled filters in quite some time but I thought the recommended cleaning procedure was to use low pressure water to hose off not "squirt pressure". Same comment on blowing air - both high pressure water and air can cause damage to the cotton pleats.

For those who want to use the K&N filter please follow their instructions on how to service them. According to the member who posted the link to the K&N site the oil is a necessary part of their product. It's actually the oiled media that catches the dirt. Suggesting that you don't have to reoil is wrong and dangerous. Suggesting you use anything other that an oil recommended expressly for this purpose is also wrong. If these maintenance steps are too hard to follow then just use the excellent factory dry media and replace according to factory specs.

Quotes source post: 14058441

drop a few potatoes in the oil filler tube and catch the French fries as they come out of the tail pipes.

Replaced the AOS yesterday. I will regret that decision for a while because that was by far the most aggravating DIY job i have ever done. When they say we recommend dropping the engine from the car, you should probably think about doing that. plus all of the old vacuum lines that were brittle and broke that i had to replace. But got it in and bolted back together and hopefully that will be the end of that. now time to go oil the air filter in bacon grease