I just failed my emissions test with the gm846 cam. I don't have any emissions stuff on the car but am in the process of installing a converter. Which cams have you guys seen that have been emissions friendly or what have you done to make your cams pass?

 

This is for CA, but it's good info:

http://impalassforum.com/noncgi/ulti...c;f=1;t=000062

 

I passed Marylands "treadmill test" without even being close. CC305, ported heads, 95,000 mile bottom end, 30# injectors, and 58 MM throttle body. Since I'm running MAC headers, I can still throw a cat on it to get it through inspection.
Gotta love an emissions legal 12.0 second car...lol

Frank

 

Hate to be negative, but your never gonna pass with that big cam and the EGR and air removed. Even with a converter your beatin your head agianst the wall. Get the air and EGR back on, make sure the tune is spot on, and you might get close. If you can get close I've seen people disconnect injectors to pass. Disconnecting the injector will dilute the exhaust with unburned air and lower the measured emissions.

You can also try dumping alcohol in the fuel as it burns much cleaner.

Good luck

 

BTW, my car does still have the EGR and AIR hooked up and functioning.

My tuner at PCMFORLESS also assures me that we can get the new 355 through emissions with the GM847 IF I keep the EGR and AIR hooked up, and run the cat on it.

Also wanted to note that my car failed emissions when the motor was completely stock...Of course I didn't have a cat on it, though


Frank

 

I do have the EGR hooked up. I may have to lean it out a bit and try some of that gas treatment to get it to pass, along with the new cat.

 

straight from the comp cams tech guys: the 305 is the largest cam they sell that will pass emissions on a stock tune. anything above the 305 will need an emissions tune and ev ery lt1 i have ever seen wont pass emissions without the cat on it. my car comes close but the hydrocarbons are a little high. i cut off my factory cat and welded a starter tube on the cat and it is the same length as my or pipe so i swap it in and it barely registers any emissions at all. i also put it on during long highway trips to kill the drone of the exhaust but fab up something like that and you should at least pass.

 

I made it through emissions with my cam. It's a custom grind 228/238 duration, .510/.510 lift on a 112 LSA. We have a dyno sniffer setup here. I barely passed.

 

I was wondering ,if any one has tried adding a 3rd cat on cars with two cats? Would this clean the exhaust enough to pass a cam larger than a CC305?

 

If you did this it might clean up the emissions but it would be a big impedance in the exhaust and would drain some serious HP. I wouldn't recommend it.

 

What is considered an emissions tune? Pulling timing and tuning towards the lean side of the spectrum?

 

Passed the IM240 treadmill here in MD quite easily with the HOT cam the last time I had to get it inspected. Car was a 96 WS6.

 

I was only thinking of doing this just to pass the test.. Cali smog requirements are very tough.

 

You will not pass emissions with the EGR/AIR removed. I failed my N2O because i had my egr unplugged only, had to pay a bit before i passed the 4th time i took the test.

I've heard that you can pass the threadmill test with the CC306, just depends on who tunes it. If not then you could get a tune to adjust the car just for emissions, and then put everything back to normal after ya pass.


How badly did u fail and which parts?

 

Mine is a '93, which means it has a chip. PCMFORLESS did my tune via mail order. It's the same tune the car went 12.0 on AND passed emissions on.

Frank