MMNuke_996

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?

jhbrennan

Replace with OEM paper filter.

williamr91

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.

MMNuke_996

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?

dan_189

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.

Hurdigurdiman

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.

MMNuke_996

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.

Schnell Gelb

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

5CHN3LL

"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)...

MMNuke_996

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.

5CHN3LL

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.

OKB

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

Noz1974

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 !!

Noz1974

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?

m3driver

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