Vacuum leak - smoke test shows smoke coming from under the air oil sperator - 986 Forum - The Community for Porsche Boxster & Cayman Owners

BYprodriver · 09-09-2019, 10:21 AM

Quote:

Originally Posted by Starter986

I replaced my AOS just a short while ago. It does have a boot that attaches from the bottom of the AOS to the engine. Yours has been replaced as evidenced by 1. The worm drive clamp, and 2. That's the newer AOS part. The newer AOS round piece on the top is vertical while the older part round top is horizontal. That said... when I removed my old AOS that bottom boot was like butter and, because I was replacing in... I just tugged at it and it came right off. When completely I pulled off the old one I just removed what was remaining of that boot.
See if you can source that boot for a better price (

https://www.ebay.com/p/Porsche-Oil-Separator-Boot-996-Carrera-986-Boxster-Genuine-99610723752-Bellows/1822097375?iid=323690532260&chn=ps&norover=1&mkevt=1&mkrid=711-117182-37290-0&mkcid=2&itemid=323690532260&targetid=800915196857&device=c&mktype=pla&googleloc=9031411&poi=&campaignid=1497794122&mkgroupid=56281259685&rlsatarget=pla-800915196857&abcId=1139466&merchantid=114749148&gclid=EAIaIQobChMIveC3oPXB5AIVgZOzCh2hEQwMEAkYBCAB EgKnVPD_BwE) and, after removing the rear wheel and shroud... go to town on it. Shouldn't take but 30 minutes jacking up the wheel.... removing shroud... removing old... installing new... reinstall shroud and wheel and your good to go.

AOS diaphragm has been vertical since 1998

Starter986 · 09-09-2019, 10:44 AM

Quote:

Originally Posted by BYprodriver

AOS diaphragm has been vertical since 1998

I replaced my AOS a while back... and it was horizontal. The new/updated one I installed the diaphragm was vertical.

Did Porsche come out with that update the same year of production? Was the car manufactured with both versions? I'm curious.

Vtx531 · 09-09-2019, 12:51 PM

Pulled the AOS today. Pretty easy job. The lower hose quick connector was already broken from the last guy (he owned a shop) but it seems to be sealing fine.

I inspected the bellows and besides the fact that it seems out of shape (maybe from heat) I was able to reinstall and tighten a screw type hose clamp but I don’t like the fact that there is no lip on the metal fitting the bellows goes on to. Seems like it can easily come off again in the future.

The AOS was a uro parts one so obviously replaced before. Previous owners used cheap parts all over this car. For example the brake rotor hats are all rusted. Annoying.

Smoke test after was good. No smoke and the system seemed like it was holding a bit of pressure.

I pulled the negative terminal of the battery to try and reset the ECU. Let it stay disconnected for about 10 mins. When I reconnected it the car ran really rough, missing and knocking a bit (through the intake). I would have though that would reset the fuel trims and it should have ran a lot better initially? Ended up smoothing out after a minute and runs good now. No check engine light yet.

What is the proper way to reset fuel trims or ecu on this vehicle?

I think I’ll leave the uro AOS in there but maybe put on a OEM bellows. Any opinions? There was a little bit of oil in the intake but no smoke out the exhaust.

thstone · 09-10-2019, 07:41 PM

Quote:

Originally Posted by Vtx531

I pulled the negative terminal of the battery to try and reset the ECU. Let it stay disconnected for about 10 mins. When I reconnected it the car ran really rough, missing and knocking a bit (through the intake). I would have though that would reset the fuel trims and it should have ran a lot better initially? Ended up smoothing out after a minute and runs good now. No check engine light yet.

What is the proper way to reset fuel trims or ecu on this vehicle?

Its normal for the engine to run like crap for a bit after resetting the ECU. Resetting the ECU also resets the fuel trims. The ECU will continue to vary the fuel trims as you drive in varying conditions (cold, warm, hot, idle, mid-throttle, full throttle, etc) to find the optimal settings.

BYprodriver · 09-11-2019, 10:48 AM

Quote:

Originally Posted by Starter986

I replaced my AOS a while back... and it was horizontal. The new/updated one I installed the diaphragm was vertical.

Did Porsche come out with that update the same year of production? Was the car manufactured with both versions? I'm curious.

I believe it was phased in late 1998.

My Motorsport AOS has a horizontial diaphram.

Vtx531 · 09-17-2019, 05:28 AM

Well, check engine light came back on. Reason being - the boot slipped off again. I didn’t think it would last long. How is there not a retaining lip molded into the mounting on the engine? Grrrrr

Vtx531 · 09-18-2019, 06:13 AM

See this thread... AOS - 2 diff models - boot/no boot - which year is which?

Vtx531 · 09-22-2019, 07:37 PM

Replaced AOS with genuine Porsche unit. CEL is back P1126 P1133. Maybe another smoke test is in order but it seems like it is cutting out and hesitating when under load and snapshot showed CEL triggered at 18.8% load.

Any thoughts? Perhaps I need to run some graphing software to see what is going on at higher loads?

Latest snapshot:

P1126
Sys1 CL
Sys2 CL
Load 18.8%
ETC 187 degrees
Sft1 19.5
Lft1 28.9
Sft2 18.0
Lft2 26.6
Rpm 2440
Vss 45

Prior to replacing AOS and resecuring the boot I was getting P1128/P1130 triggered with P1126/P1133 pending.

Prior snapshot:

P1128
Sys1 CL
Sys2 CL
Load 2.0%
ETC 226 degrees (had overheating issue that is now fixed)
Sft1 -3.9
Lft1 14.1
Sft2 -4.7
Lft2 13.3
Rpm 680
Vss 0

The original code/snapshot looks like a classic vacuum leak but the new one maybe a MAF sensor?

Any help appreciated!

blue62 · 09-22-2019, 08:01 PM

What year is the car?
Miles?

blue62 · 09-23-2019, 03:03 AM

Quote:

Originally Posted by Vtx531

Replaced AOS with genuine Porsche unit. CEL is back P1126 P1133. Maybe another smoke test is in order but it seems like it is cutting out and hesitating when under load and snapshot showed CEL triggered at 18.8% load.

Any thoughts? Perhaps I need to run some graphing software to see what is going on at higher loads

Latest snapshot:

P1126
Sys1 CL
Sys2 CL
Load 18.8%
ETC 187 degrees
Sft1 19.5
Lft1 28.9
Sft2 18.0
Lft2 26.6
Rpm 2440
Vss 45

Prior to replacing AOS and resecuring the boot I was getting P1128/P1130 triggered with P1126/P1133 pending.

Prior snapshot:

P1128
Sys1 CL
Sys2 CL
Load 2.0%
ETC 226 degrees (had overheating issue that is now fixed)
Sft1 -3.9
Lft1 14.1
Sft2 -4.7
Lft2 13.3
Rpm 680
Vss 0

The original code/snapshot looks like a classic vacuum leak but the new one maybe a MAF sensor?

Any help appreciated!

Your current snapshot and the fact that you have hesitation under load suggest a vacuum leak.
I would buy a vacuum gauge (about $20.00 at most auto parts store). and do an intake vacuum test. Should read 18-22 on the gauge with a steady needle at idle.
That will prove out yes or no on the possibility of a vacuum leak problem.

If you suspect a faulty MAF sensor unplug it. Take the car for a short drive and see if that improves engine performance. If it does then the MAF is faulty, if it doesn't then most likely the MAF sensor is not the problem. But the wiring to the sensor could be.

Your latest work on the AOS could be related to your current codes. double check your work. Make sure everything is connected correctly and that you didn't knock some wiring or vacuum hose loose in the area of your work.

Since your car is a 2001 it has E-gas throttle (drive by wire) after you disconnected your battery did you recalibrate your throttle when you reconnected the battery???? Before starting the car.????

Starter986 · 09-09-2019, 04:07 PM

Quote:

Originally Posted by BYprodriver

AOS diaphragm has been vertical since 1998

This was the type, horizontal, that I removed from my car replacing it with the newer/most current part, vertical. I had read that the horizontal diaphragm would often quickly fail on the horizontal model, so the part was modified with the diaphragm vertical.

Are you saying that when the car was manufactured the factories were installing both versions?

Thank you.

Starter986 · 09-11-2019, 04:22 AM

Quote:

Originally Posted by Starter986

This was the type, horizontal, that I removed from my car replacing it with the newer/most current part, vertical. I had read that the horizontal diaphragm would often quickly fail on the horizontal model, so the part was modified with the diaphragm vertical.

Are you saying that when the car was manufactured the factories were installing both versions?

Thank you.

BYprodriver, did I stump you or are you still scouring the interwebs looking for the content that will substantiate your claim?

BYprodriver · 09-11-2019, 07:47 AM

Quote:

Originally Posted by Starter986

BYprodriver, did I stump you or are you still scouring the interwebs looking for the content that will substantiate your claim?

No it's called hands on experience.

Starter986 · 09-11-2019, 09:09 AM

Quote:

Originally Posted by BYprodriver

No it's called hands on experience.

Oh, I know. I know you know I know you know your ****************.

You're on my go-to list when I run a search. Several times I've pulled up a bookmark referencing your particular-scenario advice and recommendation, and they haven't failed me. 986 members following your advice have, collectively, saved... at least $1,000,000. At least.

My hat is off to your wisdom.