Calling on 986 Forum Master Mechanics

[Jager]

Originally Posted by Dragonwind

I have a CAT for one side never used if you are interested.

Thanks for the offer, is it a TWC for bank 2?

[jim_hoyland]

I have a related situation and question. My last two CA smog tests were close to failing. The max HC at low rpm is 58ppm; both tests, one this year and another two years ago, showed my '98 low mileage Boxster at 57 ppm- too close for confortable.

This year I did the following as suggested on this forum: replaced spark plugs, ran two tanks with techron, and drove the car harder than normal. The car was hot upon delivery to the test station.

What might be the cause of the high HC measurements ? Is there a systematic approach to eliminating various causes ?

[JFP in PA]

Originally Posted by jim_hoyland

I have a related situation and question. My last two CA smog tests were close to failing. The max HC at low rpm is 58ppm; both tests, one this year and another two years ago, showed my '98 low mileage Boxster at 57 ppm- too close for confortable.

This year I did the following as suggested on this forum: replaced spark plugs, ran two tanks with techron, and drove the car harder than normal. The car was hot upon delivery to the test station.

What might be the cause of the high HC measurements ? Is there a systematic approach to eliminating various causes ?

Several things possible; dying cats will definitely do it, as will leaking injectors, or aging O2 sensors. Get the car scanned on a Porsche specific system like the Durametric used above, it will allow you to check the functions in real time.

[Tweetdriver63]

I know it's been a few years since anybody posted to this thread, but I have a question.

According to what I've read here, and what my Durametric tells me, both of my cats are excrement. The sensor voltage behind both cats is all over the place. Before I go spending a bunch of money, can I tell from Durametric of the sensors giving me those readings are good? Resistance on the sensors on both sides shows basically zero (steady) behind the cats, and both show a steady value forward of the cats too (sorry I didn't note the actual values forward, but with both bank's showing, the line for the value forward of the cats showed both at an identical value and unwavering.

Is that how good sensors should read?

And BTW, which cats are we actually talking about? The ones that are part of the exhaust manifolds, or the ones downstream, just prior to the muffler?

Also, since cats cost as much as they do, I'm thinking I'll just replace the system with a Fabspeed exhaust from Pelican Parts. Specifically, Pelican Parts part number FAB-986-MAXKT-M. It looks to me like it replaces everything aft of the exhaust manifolds. If I replace the entire system, including replacing the OEM manifolds with headers (eliminating those cats), what problems am I likely to run into? I don't care about emissions, since we don't have emissions testing where I live. More interested in what effect that would have due to (i'm guessing) eliminating the O2 sensors in question.

Anybody here have experience with the Fabspeed exhaust?

[BYprodriver]

Originally Posted by Tweetdriver63

I know it's been a few years since anybody posted to this thread, but I have a question.

According to what I've read here, and what my Durametric tells me, both of my cats are ****************. The sensor voltage behind both cats is all over the place. Before I go spending a bunch of money, can I tell from Durametric of the sensors giving me those readings are good? Resistance on the sensors on both sides shows basically zero (steady) behind the cats, and both show a steady value forward of the cats too (sorry I didn't note the actual values forward, but with both bank's showing, the line for the value forward of the cats showed both at an identical value and unwavering.

Is that how good sensors should read?

Also, since cats cost as much as they do, I'm thinking I'll just replace the system with a Fabspeed exhaust from Pelican Parts. Specifically, Pelican Parts part number FAB-986-MAXKT-M. It looks to me like it replaces everything aft of the exhaust manifolds.

Anybody here have experience with the Fabspeed exhaust?

I just bolted my Fabspeeds on but doubt they will pass smog.

I will sell my oe manifolds for $ 300 guaranteed to pass any smog test, they have had a easy life since I rebuilt my engine in 2010. Thanks for searching.