Loss of Power after AOS Change - 986 Forum - The Community for Porsche Boxster & Cayman Owners

jnicholson30 · 07-17-2014, 01:37 PM

Hi All,

Just wrapped up putting in a new air/oil separator (AOS). The good news is that there's no more smoke. The bad news is that it's now losing lower at 5500 RPM. I also feel it's idling a little rougher, though only slightly.

I did not do the major surgery version, removing the throttle body etc. Just disconnected the AOS from above/below and swapped it out. Screws are seated tightly. Anyone run into this before? Any thoughts?

Any ideas would be greatly appreciated. Thanks!

Jeff

- 2000 Boxster S, Arctic Silver / Black

Flavor 987S · 07-18-2014, 05:31 AM

The failed AOS may have damaged your MAF sensor. Trying cleaning and/or replacing.

Pdwight · 07-18-2014, 07:01 AM

Use cleaner designed for MAF cleaning...not just anything

jb92563 · 07-18-2014, 07:08 AM

I'm experiencing something similar.

Look here to see what is going on:
how-diagnose-resolve-engine-issues-using-durametric

None of the replacements have corrected my hesitation issue.

Still no positive proof of what has happened and the exact fix, but my latest idea after replacing a bunch of stuff is that the computer needs a reset and 25+ miles of driving to re-adapt itself and run properly and smoothly.

Have not had the chance to do that yet.

What codes are you getting?

First look should be the MAF and airleaks in the induction or exhaust header.

A reading of the codes and LTFT , STFT (Fuel trim) values are helpful when trying to solve mysteries.

jsceash · 07-18-2014, 11:26 AM

Check the hose between the AOS and Plenum and the 4,5,6 bank and AOS there are 2 O-rings on each that I would replace anytime I remove that tubes. Then check the other tubes for a vacuum leak. Also the long hose between the 4,5,6 bank and AOS can get dried out and crack sometime when pulling it around.

jnicholson30 · 07-20-2014, 09:23 AM

Hi All,

Thanks for your suggestions. Picked up some MAF cleaner and will do that shortly. Rechecked the connections. I do see something that looks like it could be an issue? I see a red rubber o-ring on the lower "input" next to the 2 bolts. I don't remember seeing one of these outer rubber o-rings on the old one. Does this look right in the images below?

I am wondering if (A) that could somehow be the o-ring that belongs inside and it didn't slide in; (B) that should not be there and I should reinstall without it; or (C) it is correctly installed.

Any thoughts?

Jeff