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Tech - that's a good plan. I'll definitely do that first. Need to check diagrams - but maybe you can tell me if you are referring to one of the circled items in the photo below? I assume you are referring to the red one.
I'd be very interested to see how you modified your system. Do you have any photos or diagrams that you can point me to?
Yes the red circled area is the AOS to plenum connection. I used a 5/8 expandable rubber/metal plug to cap off the TB plenum. Then just cut the plastic AOS hose near the insulation tape and fitted a hose from Lowes intended for use on dishwashers to it and ran to the catch can. The catch can is set up to vent to atmosphere ( although it can be set-up to work in-line ect) and additional fittings/caps/ filter are included. I do not consider this an advancement in technology, but rather a retrofit to an older tech that is less problematic and safer. Also it will not pass emission inspection. Excuse my dirty air filter, it is due for its "spring cleaning"
Yes the red circled area is the AOS to plenum connection. I used a 5/8 expandable rubber/metal plug to cap off the TB plenum. Then just cut the plastic AOS hose near the insulation tape and fitted a hose from Lowes intended for use on dishwashers to it and ran to the catch can. The catch can is set up to vent to atmosphere ( although it can be set-up to work in-line ect) and additional fittings/caps/ filter are included. I do not consider this an advancement in technology, but rather a retrofit to an older tech that is less problematic and safer. Also it will not pass emission inspection. Excuse my dirty air filter, it is due for its "spring cleaning"
Great information and good ideas. I'll try a quick temporary fix and see if it clears up the smoking. If it does, I'll look into a more robust set-up. We'll have to see if that was the source of the noise. That was my biggest concern prior to the smoke-out. Would be great if they are a result of the same issue.
Funny you mention the dirty air filter. I just replaced the master cylinder on our 86 944. Popped the lid off the air cleaner - it's got a K&N filter - and it's filthy. We might have brakes now. And maybe clutch too. But the damn alternator isn't charging. I just replaced it last fall. Now I guess I need to check wiring and fuses. Good thing I enjoy punishment...
That is a very interesting setup Porschetech. I read in another thread somewhere where these catch bottle setups cause some sort of minor mixture issues due to the variance in vacuum? No problem with your setup? Also what did you use for the actual catch can?
I know everyone says just replace the AOS, but I seem to read so many cases of brand new, out of the box AOS that fail within days or week, that I am leery of replacing something that is working (in my case reasonably well, or at least tests out with slack tube manometer), for fear of having an actual failure. I kind of like the idea of a "backup" catch can affair.
That is a very interesting setup Porschetech. I read in another thread somewhere where these catch bottle setups cause some sort of minor mixture issues due to the variance in vacuum? No problem with your setup? Also what did you use for the actual catch can?
I know everyone says just replace the AOS, but I seem to read so many cases of brand new, out of the box AOS that fail within days or week, that I am leery of replacing something that is working (in my case reasonably well, or at least tests out with slack tube manometer), for fear of having an actual failure. I kind of like the idea of a "backup" catch can affair.
My AOS failed a year and a half ago at "Little Talladega" Road Course (TGPR). Our local club had rented it for a track day and at the noon session my AOS failed, big cloud of smoke on start up. Yes, I tested with a manometer to confirm it had failed. My buddies scoured the pits for items for a quick fix. Came up with a suitable vacuum plug for the TB plenum and some hose and an empty Mobil 1 liter bottle, fashioned a quick temporary fix and finished out the track day. Then I went back and made a permanent catch-can fix, with the expandable rubber/metal plug, corrugated high temp hose and catch-can (E-bay) with dip-stick and vented filter.
For a street only car I would recommend to just replace the AOS to keep stock and emission legal and no maintenance, but for me, fear of my engine ingesting a big gulp of oil and cracking a cylinder or bending a rod was enough to warrant the Mod.
Eliminating the oil vapors, blow-by gases, and moisture vapor from being recycled into the intake and combustion chamber does change the mixture , and idle speed by couple hundred rpm, but my 99 Motronic 5.2.2 had no problem adapting and readjusting idle speed to target idle speed rpm and stoichiometric air fuel mixture. YMMV
My AOS failed a year and a half ago at "Little Talladega" Road Course (TGPR). Our local club had rented it for a track day and at the noon session my AOS failed, big cloud of smoke on start up. Yes, I tested with a manometer to confirm it had failed. My buddies scoured the pits for items for a quick fix. Came up with a suitable vacuum plug for the TB plenum and some hose and an empty Mobil 1 liter bottle, fashioned a quick temporary fix and finished out the track day. Then I went back and made a permanent catch-can fix, with the expandable rubber/metal plug, corrugated high temp hose and catch-can (E-bay) with dip-stick and vented filter.
For a street only car I would recommend to just replace the AOS to keep stock and emission legal and no maintenance, but for me, fear of my engine ingesting a big gulp of oil and cracking a cylinder or bending a rod was enough to warrant the Mod.
Eliminating the oil vapors, blow-by gases, and moisture vapor from being recycled into the intake and combustion chamber does change the mixture , and idle speed by couple hundred rpm, but my 99 Motronic 5.2.2 had no problem adapting and readjusting idle speed to target idle speed rpm and stoichiometric air fuel mixture. YMMV
Great stuff. I have to thank you, Dr. Tech. There is hope and cause for celebration.
I disconnected the pipe to the plenum and found a cap to cover it. Fired up and checked for smoke screen. Naturally, there was plenty at first. It subsided as the engine ran. This was after a minute or two.
Then I moved Nico off the lift and back to spot #2. Figured I would just pull (truck and trailer) around the garage and unload the car backward and then back in toward the lift. Got the truck stuck in the mud! It's a slight incline, the tires suck, 4WD Lo was not engaging for me (probable operator error), and there's a lot of slimy clay right where I had positioned the truck. Had to back up and unload the car at the end of the garage. One man Chinese fire drill...
After a couple of laps of the circle drive, I pulled into the garage. A lot less smoke. Didn't let it run long enough to get warm. Figure to do that tomorrow. Have a fairly full schedule planned.
Here's the temporary cap. Need to figure out what to do with the fuel vent line. There's a Y-connector. Figure I'll route the AOS pipe to a catch can. Probably should route the fuel vent line to its original port. Will have to work out the plumbing and fittings.
Tomorrow will be spent messing with the Durametric. Our best buddy bought one. Just before I ordered one online, I sent him an email asking if he had one. Surprise!
I've had the book for a few days. Great resource. Ratchet1025 sent the sweet exhaust tips; the clamps arrived today.
My wife thinks I'm a god. We'll have to see how I measure up with the Man-o-meter. That's what it's for, right?
You're welcome, I hope it also proves out to be your source of IMSB-like noise.
P.S. Thank you for the honorary Dr. title you bestowed on me, "I pledge to uphold the Rennlist Tradition" signed Dr. h.c. Porschetech3
Decided to clip the connector back on and take a hack out of the middle of the AOS pipe. Kept the the fuel canister vent hose in place.
Capped off the larger inlet side with a better, but still temporary, fix. Will figure out the plumbing to run between the open end to the prototype catch can.
Decided to clip the connector back on and take a hack out of the middle of the AOS pipe. Kept the the fuel canister vent hose in place.
Capped off the larger inlet side with a better, but still temporary, fix. Will figure out the plumbing to run between the open end to the prototype catch can.
Yes this is what I would have done also. The 99 C2 with the cable TB has a separate connection on the TB for the Evap vent line.
Still getting a lot of smoke out the exhaust. Go figure. It does clear up after a couple of minutes. I'll have to see if I can come up with a suitable way to clean the oil from the intake; short of disassembly.
Hooked up the Durametric. Found another use for those, various sized, cardboard boxes I keep around.
From what little I have retained, these numbers don't look so good.
From what little I have retained, these numbers don't look so good.
Mess it fully up to temp Scott? I’m sure Doc will know, but I was under the understanding cam deviation values had to be fully up to temp or they can be off? Mine were 1.72 and .09 at full temp.
My AOS failed a year and a half ago at "Little Talladega" Road Course (TGPR). Our local club had rented it for a track day and at the noon session my AOS failed, big cloud of smoke on start up. Yes, I tested with a manometer to confirm it had failed. My buddies scoured the pits for items for a quick fix. Came up with a suitable vacuum plug for the TB plenum and some hose and an empty Mobil 1 liter bottle, fashioned a quick temporary fix and finished out the track day. Then I went back and made a permanent catch-can fix, with the expandable rubber/metal plug, corrugated high temp hose and catch-can (E-bay) with dip-stick and vented filter.
For a street only car I would recommend to just replace the AOS to keep stock and emission legal and no maintenance, but for me, fear of my engine ingesting a big gulp of oil and cracking a cylinder or bending a rod was enough to warrant the Mod.
Eliminating the oil vapors, blow-by gases, and moisture vapor from being recycled into the intake and combustion chamber does change the mixture , and idle speed by couple hundred rpm, but my 99 Motronic 5.2.2 had no problem adapting and readjusting idle speed to target idle speed rpm and stoichiometric air fuel mixture. YMMV
thanks Doc! 😉. I might consider this, particular for track days
03-21-2019, 06:42 PM
