P1128/P1130 Air Filter Problem

[ajgray925]

Hello fellow Porsche owners. This is my first post. I have done substantial research on this site and have found a vast amount of useful information and wanted to get some feedback on my exact problem(s).

I have 2000 Boxster S that I purchased used 2 years ago (23,000 miles at the time). It now has approx. 31,000 miles. The check engine light started appearing a few months after purchasing, thus I've been chasing this problem a while. I took it to a Porsche dealer in New Orleans and they performed an oil change and ran out of time to do a full analysis, but felt the check engine light problem was due to an aftermarket air filter assembly.

The air filter element was removed by the previous owner and an aftermarket cone shaped filter installed (see pictures below) as manufactured by AFE (Advanced Flow Engineering). I called this AFE manufacture to confirm if the particular filter outfitted was designed for my car. They indicated that they do not have a DESIGNED filter for the Boxster. At any rate, I removed the filter and cleaned it per manufacture recommendations, very lightly oiled, removed any excess oil, and reinstalled. I also removed the MAF sensor and cleaned it with electrical cleaner as recommended on other threads.

I have a code reader and have reset the light and it always returns within a few days. I get same code as several others on this site: P1128 and P1130. I know it could be the MAF; possibly damaged by this aftermarket air filter. From what I have read, it's probably not 1 of the 4 O2 sensors, since I get both P1128 and P1130 simultaneously. I haven't been able to find a vacuum leak at the AOS or oil filler tube or cap. I did remove the oil filler cap while engine was running and there is a good amount of suction.

The car hesistates when starting in 1st gear, especially when cold. It also will pop/backfire in 1st gear at times. Other than that, the car runs great and has never had any other problems.

Prior to doing anything, do you recommend that I install the original air filter element and an original type air filter. I called Porshe in Mobile and the cost of the material is $263. I can install myself. Should I go ahead and take the car to the Porsche dealer and have them hook up a code reader that can pinpoint the problem with engine running?

Thanks for the responses!

Andy

[MNBoxster]

Hi,

My guess is that you have a bad MAF. Replacing it will probably cure you for awhile. BUt, considering the very small gains to be had with intake mods anyway, personally, I'd switch back to the OEM intake and filter...

Happy Motoring!... Jim'99

[AUDIOGUY]

I can almost guarantee the codes are due to the intake. I have been getting them off and on for the last year. My question to Jim is will the car be affected long-term by the cel being on for the 1128 and 1130 air fuel mix issue or not. I feel that my car is running very well with the Evo intake I have either with or without the CEL on. Also, it goes out every once in a while for about 2 weeks or so and then reappears. I thougt of buying a new MAF but if it will ultimately be fouled, maybe not.
Any further suggestions.
Thanks!

[j.fro]

I have the same car (2000 Box S) and have installed the same intake/filter over 5000 miles ago with no issues (the car is at 82,000 now). I have a feeling your MAF is done, but that the intake/filter with proper oiling is not the issue. If you are worried about the oil/MAF trouble, another option to replacing the entire intake is to find a cone filter that does not use oil. Google it - they're out there, and they're cheaper and easier than going back to stock. Cheers!

[MNBoxster]

Originally Posted by AUDIOGUY

I can almost guarantee the codes are due to the intake. I have been getting them off and on for the last year. My question to Jim is will the car be affected long-term by the cel being on for the 1128 and 1130 air fuel mix issue or not. I feel that my car is running very well with the Evo intake I have either with or without the CEL on. Also, it goes out every once in a while for about 2 weeks or so and then reappears. I thougt of buying a new MAF but if it will ultimately be fouled, maybe not.
Any further suggestions.
Thanks!

Hi,

It's possible you are having trouble now and not know it. The DME may be selecting the improper Map and operating parameters, though it may seem fine to you. Longterm effects could be shorter lived emissions system and so forth.

The other issue is that these codes can mean something else entirely. There is no specific Bad MAF code, only codes such as these two which indicate symptoms leading to the discovery of a failed MAF. Some other conditions or components can throw the same codes, which you would be ignorant of until other codes appeared, or something broke, or performance suffered tremendously before you noticed. By that time, you could have caused some $erious damage, not to mention any ill longterm effects...

Happy Motoring!... Jim'99

[AUDIOGUY]

Thanks Jim,

I figured the CEL was correlated to the Intake due to the fact that it came on shortly after I installed it. When I get some time, I will bring it to a reputable guy near me to
full scan it and do some further diag.

[Strawfordt]

I had some similar problems this summer. For me, MAF cleaning seemed to really work. While researching the issues I found some people in this forum and the renntech forum suggested that if you unplug the MAF sensor the computer will run a default program. I would assume that if your troubles go away when the MAF is disconnected then you have conclusive evidence that the MAF sensor is bad.

Admittedly, I AM A NOVICE!!!!

Ask some of the really knowledgeable people on this forum, if my advice makes sense before you try this. I'll be interested to know if it works out for you.

Good luck!

[ajgray925]

Thanks for everyone's responses. To possibly save $$, I'm leanning toward replacing the cotton (oil type) cone filter with a paper cone type (in lieu of going back to the stock air filter element) and also replacing the MAF sensor. This would prevent the new MAF from becoming fouled by any oiling of the existing after market air filter and save some money on the stock air filter element that was not handed over by the original owner of the car when purschased.

In doing this, my conern in doing this is will the amount of air pressure (static pressure) allowed to be sucked in be more or less than allowed by the limits of the computer system, thus tripping the check engine light? In going back with the stock element (filter housing), there's no doubt the proper air pressure is as originally designed. I know the after market filter assemblies sold have hose connections that are lengthened/shortened and bent is a way that maintains the original air speed suction. Anyone have any thoughts on this matter?? Should I just ante up and pay the $263 for the original stock air filter housing?

Also, I did unplug my MAF and drive around town and I do have the same hesistation and backfiring problems. In doing this, another problem is actually created; the idle is erratic at times.

Thanks again for everyone's time and helping me out!