6mil928

perfect wally thanks.

dr bob

Wally--

You take all the mystique out of it when you describe the procedure that way. And thanks for that 'old, experienced' description. I just managed to make it to 56 a couple weeks ago. It's not the age though at this point, it's the mileage. And something called useful life remaining, whatever that is.

Jason, if you live a place where smog is not a serious concern, you can try swapping in a Y pipe in place of the catalyst. Just for test purposes of course. Remember also that you can actually look in the ends of the catalysts and see if the honeycomb is melted and the holes blocked. Look from the engine end, and you'll see the grey substrate in there. When it overheats, the holes get plugged as it melts. Looks like blobs of grey goo covering the holes if it has failed at all.

G Man

My car is cat free at this time. PO removed it before I got the car. If I sell the car to an individual that lives in an emissions testing area I'll have to get one to put back on there. I was thinking of picking one up from Summitt racing. They are pretty inexpensive from them. Would this work or does it have to be OEM? I have heard that the new cats don't require an air input.

danglerb

Smog test is always something of a roll of the dice, but as of jan 2009 Ca requires any replacement cat to have a CARB EO# that matches the specific vehicle. When you buy a cat now you need to use the Calif catalog and the cats now have a date as well as a EO#. YMMV

I'm going to talk with my muffler guys tomorrow to see how the new rules are playing out.

Landseer

GMan,
It might make sense to pickup an original cat system in good shape from somebody here who has removed it and isn't going back.

Right now, I'm running an 84 complete factory system on my 85 32V car.
Am doing this because the 85 sat for 10 years and the downpipes corroded through.
So, 16V systems will exactly fit the 32V cars, and vice versa, which opens up options.

The 32V pipes are duals, and on the early 32V cars they run in the same pathway under the car as the 16V cars. The 16V setup is dual to single, but the single is bigger diam.
Runs great, sounds great. Had to make a slight mod to the 85 heat shield to accomodate the location of the 84 Oxygen Sensor.



You can retro heat shields of later cars to the earlier ones, also, if you want to split the flow side to side, like I did with the 84 below. It feels better with the 5 speeds because you don;t have the passenger side automatic transmission lines above the heat shields. Not sure if the trans lines are crammed up above the shields on a newer 32V with split routing, or if they are routed differently to keep them away.

For the 84 5spd, I bought a new aftermarket cat setup, collectors to a dual in/out cat. It is actually listed by Eastern Catalytic for the 85/6 cars. Then I had a dual system made by a local shop to match-up, and it is split with one resonator under the pass side, one under th drivers side. Its not necessarily high-flow, but it works great. The Eastern Catalytic folks design and build them in Pennsylvania, so you might be able to get a tech on the phone and get some industry input on your options. They sell high-flow as well. I got their owner and he was very helpful.

Cats can be replaced by shops, so long as they certify that the cat needed to be replaced, not just opportunistically. This would be particularly important documentation to get a mechanic to fill-out I think, at least academically, if the state inspectors are zealots. Am thinking it would be useful if deleting the air injection, to go with non-air newer style. You would need that, again theoretically, to describe why the air pump is missing (compared to the engine compartment stickers saying it should be there). Something to talk to Eastern about.

One would think selling a car to a Californian would not be an easy thing, no matter how its sliced. I'd just say "no" to that.

devilinblack

Grrr! This thread got dug up and jinxed my car!

No start this morning. Swapped the fuel pump relay, no dice. Jumpered the fuel pump, same thing. Gave up and rode the bike to work (which I should have done anyway). I'll do more troubleshooting tonight, I just thought the timing was funny.

blown 87

Not Bob, but maybe this will help.

You can buy a adapter or make one out of a old spark plug to hook up a old vacuum/fuel pressure gauge to the adapter.
Screw this in the hole for the O2 sensor, if you see any thing over about 3 PSI on the gauge you have a restriction.

6mil928

Sweet idea!!!!!!!!!!!!!!!

dr bob

Great idea, Greg!

On the Cali Cat and smog check-- The times that my car has been 'inspected' here, the tester isn't quite ready to pull the trays off to check the cats. He just asks if theye are there, and if anything has been changed since he last saw the car. It really helps to have a stock/original appearance in the engine bay. And a quiet car.

SharkSkin

Stephen, how does it sound with the hollow cat? I have heard that it might sound a bit "boomy"(especially inside the cabin) with that big hollow chamber. Can you post a sound clip?

devilinblack

It is a little noisier. Since it's a bit rich and I get some popping as I decelerate that can almost sound like a rattle. I've got a bunch of in car video from the track but you can't really hear the exhaust, so I'll see what I can do about getting some useful audio of it.

SteveG

My '85 wouldn't pass the gas -- inspection that is. It smelled sweet. Checked it all over. We discovered the cat had been gutted; assume it was for HP, not from a malfunction. This is NY; how are you going to pass in Cali? I also wonder if Porsche set up the LH fuel injection system with a cat for the US market, doesn't the LH/EZK need some measure of back pressure from the cat? OTH the only sensor in that area is the O2 which is out of the loop after 2 to 3 minutes(?), so does back pressure enter into the LH/EZK equation. Apparently zero back pressure is good, enquiring minds. YMMV.

devilinblack

I'll pass by putting a new cat on and reinstalling my air pump at some point before then as well. I've got just over a year to get it done so I'm not sweating it too much.

dr bob

Steve--

Oxy sensor is used after a few seconds following engine start, as soon as the little heating element and the exhaust gas flow het the sensor element up to temperature. Under high loads, the LH goes to a map and pretty much ignores the oxy sensor. For all Cali tests the sensor is in the loop.

Many moons ago, doing emissions spec stuff for that Italian car company with the horse in their logo, we fab'd a bypass around the cat that went open when load came up. During all formal tests the gas flows through the cats, but under high load it was allowed to go around. That lasted a couple years in production before it was banned. They changed the rule book on us...

blown 87

Reminds me of the hood switch on a C4 Corvette, they rigged the computers to a different map when the hood was open to get better EPA mileage ratings, they always ran the cars on the dyno with the hood open for cooling.