Oil on Secondary Air Injection Check Valve?

Hi Everyone, In doing a transmission-out service, I happened to get a look at the Secondary Air Injection Check Valve and I'm not sure what to make of it - there's quite a bit of oil on it. What could be causing this? I'm not too familiar with the vacuum system on the 996 just yet - but it looks like the source of the oil is coming from the throttle body??? Thanks, Mike

The is NOT the SAI check value, which is gray and has an electrical connector to it. The valve is a one way valve that only lets vacuum into the vacuum tank (the black round canister on the right of your photo). I agree with you that it looks like the oil is from the throttle body. Do you have oil accumulation at the bottle of the TB where it connects to the T-plenum? What's the crankcase vacuum level?

https://rennlist.com/forums/996-foru...omponents.html Your vacuum valve is relocated but functionally the same.

If your AOS is going bad it causes a lot of oil to be in the intake system and various vacuum hoses/check valves will have oil just like that. It may be just the start. That check valve is on the vacuum system. How's your oil consumption? See this picture for vacuum line routing. You can see it takes vacuum from the intake manifold.

Thanks Guys! This was the part I found in the diagrams: http://www.pelicanparts.com/More_Inf...110-950-02-OEM Do you have oil accumulation at the bottle of the TB where it connects to the T-plenum? I will have to check this... not sure how. What's the crankcase vacuum level? I haven't put a meter to measure the vacuum yet, but, there is a strong change in engine note/idle when I remove the oil filler cap. Mike

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Thank you! Oil consumption seems high in the 250 miles or so since I purchased the car... I got it fairly cheap and in rough shape (shot transmission among other things). So I'm in the process of bringing it back to full maintenance. Sounds like I should replace the AOS then... FYI - 105k miles on the car and I have no service history. Here's my other thread: https://rennlist.com/forums/996-foru...-ring-diy.html Mike

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Hi Everyone, I Just ordered a new AOS. At the moment, I have the transmission out of the car (doing an IMS, RMS, clutch etc) and was wondering if I should try to replace the AOS from the rear of the engine? Is replacing it from the rear quicker than if I do it from the front? Thanks, Mike

It took me less time to do it from the bottom only but it's still a pain in the a$$.

Hi Guys, So I replaced the AOS, and, completed the RMS and IMS jobs at the same time. I checked the timing by rotating the engine by hand several times, and, the timing all lined up. This is a 1999 C2 so skipping teeth on the chain is unlikely given the 5 chain motor, but I had the cams locked and the crank locked at TDC during the job. I Started the car today and it ran rough, but, at higher RPMs it was smooth. Then after about 2 minutes the check engine light came on, then, a little while later started flashing. I plugged in my ODB reader and got the following: Stored: -P0300 = Random Misfire Detected -P0306 = Misfire #6 -P0304 = Misfire #4 -P0305 = Misfire #5 Pending: -P1319 = Misfire Emission Related -P1318 = Misfire (Cylinder No.6) Emission Related -P1316 = Misfire (Cylinder No.4) Emission Related -P1317 = Misfire (Cylinder No.5) Emission Related Looks like I screwed something up... No cam position codes, so I think the IMS is fine. So, something I may have done wrong: When I replaced the AOS, it spilled out coolant. I didn't replace the spilled coolant (was going to do that later on). The amount of coolant spilled was maybe 1-2 cups (if that). I believe I got the connections to the AOS correct and I used worm clamps that I made pretty tight. Not sure what to make of this other than I uncovered another fault? The car ran slightly rough when cold when I got it, but, it never had the CEL on... could it be that the replacement AOS made the root problem worse? Any suggestions would be welcome. Thanks, Mike

I am working on a similar problem so may be able to help.Your issue is Bank 2 ONLY. Since only those 3 cylinders are misfiring - what is a common factor to all 3 ? You'll have to start with basics - ground points,vacuum leaks, connections on the coils, valve timing Some of this is known only to you - what did you do that only affects Bank 2 ?? In my case I am so limited on time that if in doubt when I remove something ,I fit a new one. - coils, plugs,spark plug tubes& seals , Camshaft sensor ,Variocam Actuator&Solenoid. I try to do methodical diagnosis and have made many different diagnostic cables and use Durametric but time and accessibility are the big constraints . Problems like this are difficult to begin resolving without Durametric info. to share on the Forum. Good Luck.

Thanks, What ODB reader would I need to get more specific codes? I read on one thread that the variable timing solenoid might be going bad, and, that a more advanced code reader will say this specifically. It would nice to get as much info as possible prior to replacing parts. Mike

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Those are rich misfires. If the VarioCam solenoid connection is bad (either you on purpose disconnected or by accident disturbed the connection while you were working on the car) this can result in misfires confined to one bank. Because the VarioCam system isn't working right for the bank the O2 sensor readings are off and the DME will adjust fueling to try to get the readings it wants and in doing so will go too far and misfires are the result. Best carefully check the VarioCam solenoid electrical wiring hardware and its connection to the main harness is good. Another possible explanation is the fuel pressure regulator has been disturbed in some way and fuel pressure is too high. The #2 bank might misfire before the #1 bank due to normal bank to bank differences. Bottom line is last thing touched first thing suspected and swapping out a bad AOS gives one the opportunity to touch a number of things. An off the shelf OBD2 code reader can read active/pending codes, freeze frame data, and allow you to view engine telemetry, for instance short/long term fuel trims, but it does not allow you to go deeper like the Porsche diagnostic computer allows, which would allow you to check camshaft timing variation (if any) and manually activate/deactivate VarioCam operation.

Any intake parts you removed while doing the job?

Macster, This is good info. I used a wire brush while cleaning certain engine areas (caked on oil spots). I did some cleanup to trace an oil leak to the hose connecting the AOS to the top of bank 2. Is this the area where the vario cam solenoid lives? If so, I likely hit it too hard with the brush... I'll have to take a closer look tomorrow. Sounds promising... Ahsai, I removed the airbox... and that's about it. While working on the car, I also likely loosened and not tightened the coolant cap, or, the oil filler, or, the dipstick... As a side thought - I'm thinking I have to bleed the coolant? Did I introduce air bubbles into the system by replacing the AOS? Anyway, I'll update tomorrow after I check vacuum connections and the vario cam solenoid connection (need to find out where this lives). Thanks, Mike

You may have introduced air bubbles, but that wouldn't have anything to do with those codes. Fill her up and drive around with the vent valve stuck open for a drive.' Check all the connections going to the variocam sensors. Double check all vacuum lines near the AOS.

Brief update: I started lightly tugging on some of the vacuum connections, and, in the diagram below, I pulled on point B and it immediately came loose from the point attached at the back of the engine. So I have to figure out how to get to that vacuum connection.... Also, I pressed on the vario cam solenoid connection and it was hard to tell if it "clicked" a bit, or, if the noise was some plastic bits falling off. This connection is likely in need of replacement as it was brittle and caked in oil.

Just wanted to give everyone an update. I found quite a few issues that I then needed to dive into: - In order to get to the disconnected vacuum line, I took off the throttle body. - Upon cleaning the throttle body, I took off and tested the Idle Air Stabilizer Valve, and, it was completely stuck open with tons of caked on grime. I couldn't see the flap, and, it wouldn't move at all with applied voltage. -After many Qtips, MAF cleaner and WD40 the valve started operating when I applied Voltage from a 9V battery. - Upon inspecting the oil filler tube, I found a fairly large crack. When I bent the tube to get a better look at the crack, the oil filler tube broke completely apart! So I had to remove the alternator and pull out the oil filler tube LOL. So now I have new parts arriving today and this should get me further along the rich/rough running debug process! Thanks, Mike

Ah, the merits of 15 year old plastic that's been through thousands of heat cycles! Good luck with your fixes

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Thanks! Another update. Last night I replaced the oil filler tube and re-installed the throttle body with all new seals as well as a cleaned out and functioning IASV. Same problem LOL. The car starts up well, sounds good above 1000 rpms and then proceeds to dip down below 700, then 500, then it starts to stumble, feels rough, idle not constant. Smells pretty rich as well. Unless I open throttle it feels like its going to cut out. I didn't run for more than 15-20 seconds, but, the issue is definitely still there - but the issue seems more pronounced now. I'm thinking I'm poking at a major intake leak here. Below is how I debugged the vacuum leaks in my 928, will this work for the 996 intake system? I used an adapter (made from hardware store parts) to pressurize the intake and listen for escaping air. It worked really well for the 928 intake. I think the sizes are about the same, so, in theory, I should be able to pressurize the 996 intake and hear leaks, right? The picture shows the 928 throttle body off the car, but, the technique worked the same with it on the car. With the 928 all the air/oil stuff is hard to get to with the TB on.

Went home for lunch today and decided to try something... I disconnected the MAF. With the MAF disconnected, the car idled higher, but, it actually ran smoother!!! So I took the MAF out, cleaned it out, nudged the pins off center a bit (this is to make sure there is contact force upon connecting) then reinstalled. I then cleared the CEL codes via the ODB port and started the car. At first the idle was moving around, bumpy, but, the idle was less lumpy than before. Maybe the ECU was trying to find the right settings? After a few minutes, it started getting a bit better. After 5 minutes, still no CEL light, and it got pretty smooth. Engine temp was climbing the whole time. I let the car idle at temp for another 10 minutes and it was a smooth and fairly consistent idle. No CEL. Revved a few times to 3k. No CEL. Engine even sounded decent.... So either the MAF cleanse fixed this, or, its a cold-engine problem. Anyway, a result! Not sure what else I can start looking at for the time being...