[968Syncro]

Here are the detailed results. I am convinced the variocam is a huge advantage each time.

   

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[Chris Vais]

It makes you wonder whether the air that the car takes in on a hot summer afternoon in California is more polluted that what comes out the exhaust. If true, we could offer our to drive our cars as a pollution offset. [img]style_emoticons/<#EMO_DIR#>/biggrin.gif[/img]

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[flash]

they actually used to advertise that very fact in their marketing literature

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[ds968]

Got my smog check notice yesterday. This will be the first time with the SC on , I suppose with stage 3 I have nothing to worry about but I'm probably still going to pump 5 gal of 100 octane in the tank and run it for about half hour, with frequent revs at high rpm before the test just to be absolutely sure..am I overreacting for no reason at all ? Last smog test was as most people here, essentially o readings across the board, as Chris pointed out these cars spit out cleaner air than they take in , LOL.

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[flash]

believe it or not, that's actually a bad idea, unless you have a cat that is suspect. the temp sensors and controls in the system could mistake things and start messing with your mixture.



just get the car fully warmed up normally, with your normal chevron fuel.



regarding the cat, you have pretty high mileage on yours. it could be getting ready to croak. i would start looking around for a backup just in case.

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[ds968]

got it, will leave the octane at 91 huh ? " cat getting ready to croak " at just 115k miles ?! there hasn't been more than two or three recorded cat failures on any 968.. to my knowledge . <img src="/forum/images/smilies/968/huh.png" class="smilie" alt="" /> . am told these cats are good for AT LEAST 250k miles.. which if true, is good news because the part in NLA.

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[flash]

nope - they are only 100k cats. for cars in our era, there is no such things as a cat that goes past that, and in fact, most of them are only 60k. not even sure there is anything any better in today's cars.



typically we start seeing clogging not far past 100k. i have personally seen 4 toast at just over 100k, but i haven't had that much occasion to be inspecting cats. depending on how the car was run, the fuel run in it, and all that, the failure point can vary.



by the way, the aftermarket cats i've tried are crap. couldn't get them to pass without a LOT of persuasion.

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[bombfactory]

I'm at 130k now and the car passed smog with no problems two years ago (probably at around 125k) - pretty sure the cat is original. I'm due again for smog - overdue now actually - since the car is still not running. Will report in as soon as I'm back on the road and get the test done.

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[flash]

it happens. i know they start showing up as clogged though just after 100k. i haven't seen or heard of any under that, but enough over that to make me concerned.

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[Cloud9...68]

How would you know if your cat is clogged, or in the process of clogging?

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[DaveN]

If it eats a lot of kibble and nothing comes out the other end <img src="/forum/images/smilies/968/wink.png" class="smilie" alt="" />

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[flash]

lol - fair enough



http://www.ehow.com/facts_4854981_signs-...erter.html



youtube link - delete the spaces



www.y o u t u b e.com/watch?v=IzyvL5tQLzU

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[ds968]

if all aftermarket cats are proven ineffective, and the oe cats are "nla", I'd think you can petition and be granted an exception from the state from smog checks.. <img src="/forum/images/smilies/968/huh.png" class="smilie" alt="" />

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[flash]

yeah, but you have to do something dumb, like try 3 times, with different cats, at YOUR cost, and fail all 3 times, then you can petition CARB, in order to get that exemption. the upside is that it makes your car smog exempt from there on, so maybe well worth it in the end.

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[ds968]

[quote name='flash' timestamp='1367344951' post='142084']

http://www.ehow.com/facts_4854981_signs-...erter.html

[/quote]



wait, all of those symptoms also point to the DME relay going bad <img src="/forum/images/smilies/968/laugh.png" class="smilie" alt="" /> ok, maybe not the rotten egg smell, but the rest could.., so PSA : change your $ 25 DME relay before you spend $ 1,000 on a suspect bad cat <img src="/forum/images/smilies/968/wacko.png" class="smilie" alt="" />

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[Chris Vais]

Flash, I recall reading in a post on this forum, that we had to have the OE cat in place to provide proper exhaust back pressure. If the cat fails and there is truly no replacement, what should we install to maintain the appropriate back pressure? It doesn't sound like a good idea to leave a failed cat in place.

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[flash]

"back pressure" is one of those terms that gets tossed around a lot. no engine should have any real back pressure.



that being said, there should be a certain amount of restriction. in a naturally aspirated 968, this is incredibly important. the cam overlap comes into play here, and the pulse timing is very touchy. serious torque loss occurs when the restriction is relieved too much. you often gain a bit of upper end horsepower, but at the expense of low midrange torque.



the best thing to do is find another OEM cat. other than that, it's going to be trial and error. i tried a couple of aftermarket cats, and did not have a lot of success.

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[ds968]

While reading the link flash posted I ran into a few more links with tips on how to give yourself the best chance of passing smog if you suspect you may be too close for comfort ; the usual - tune up the car, oil change ( clean oil apparently helps also ) gas up with premium and use the brand with the cleanest additives known , AND this : make sure your tires are properly inflated if the test includes a "dyno" roll ..which in California it does . They claim that improperly inflated tires can make the engine run inconsistently on those rollers and give off weird exhaust readings in the process.. ..Seriously ?!!

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[ds968]

The fine state of Kaaali-fascist-fornia now is now compelling certain cars ( including the 968 ) to the new " Star " smog stations which I thought were simply renamed from the former gold label, smog check only stations but nooooo, there's a new twist to them : in addition to newer more sensitive equipment they have cameras installed so the CARB can look over the shoulder of the technicians to make sure they're doing everything by the book, and the cameras are set up in a way they can also see what's under the hood, just so the tech misses nothing And guess who will be paying higher smog check fees to make up for the extra equipment cost of these stations ?! Arrrrgh, time to register the car in Nevada next year :-) !

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[flash]

that's why i went to the trouble and expense of the CARB certification

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