I'm freaken pissed. Today I failed the PA state sniffer test in all 3 categories and I freaken tripled the state maximum numbers for each category. I just put on new plugs/wires and new 02's so its my freaken computer tune. I had my PCM tuned by MadZ28 and now not only did my mpg go down from 15 to 10 but I completely failed the freaken sniffer test. Apparently my car is running so rich that my cat can't get rid of any the harmful gases. What the heck should I do, MadZ28 won't respond to me and I need a stock computer or something I guess???

 

try a new cat

 

I can see A new Cat but why so rich?
do you have files from madz28............

 

is your car obd1 or obdII?

 

He has a 1995, so it should be OBDI. You might have to get it re-tuned there bro..

 

Its an OBD1 and I dont know why its so rich. I have a brand new Carsound Cat on there as well but I heard a rich running car can fry these cats so I dunno. I definetly know that my tune is way off because everything is wack. All I have from MadZ28 is my ordersheet.

 

I like LT1 Edit, I watched the guy that did mine, he did all kinds of ****. It runs like a champ, I have to get the EGR tuned out when I block it off. He is cool about it though, I have to get the shift points adjusted, he is going to do that for me.

 

Where is your cat located? It's probably too far down the exhaust stream to heat up enough and work properly. You might need to switch to dual cats that are located closer to the engine. But I would start with going back to a stock tune and see what the numbers look like.

 

id love it if mine would pass emmissions but theres no way in hell...last time i used my schools sniffer i was on 7 cylinders and the sniffer stopped at 9999 hc's (limit is 250 in texas atleast)

 

Right after the Y which may or may not be a problem. I'll have to see after I get my new computer on tomorrow. I really hope I don;t have to redo my exhaust again

 

Hate to say but I agree with Jeff... it's probably just not getting warmed enough. I passed with LTs, DUAL cats in the y-pipe, and that was NJ sniffer. Good luck man.

-J

 

Failed here too, I also have the cat after the y. maybe I might have to hack away and add a cat on each side of the y and keep the third, and get it tuned. This blows

 

Dual Cats should be enough, that third might take power away. I would put one between the Collector and the Y of the pipe, that would probably be the best bet, and keep power loss to a minimum.

 

you need to hook it to a scanner and see what your fuel trims are doing.


how hot was the car when you had it tested? the hotter the better
maybe throw your stock tstat in it


your running the stock fuel regulator correct?

 

I have the stock thermo back in just for this occassion, I even disconnected a fan relay just so i'll run hotter. and yes it's the stock fuel regulator. I think a tune is in order.

 

i just dont see how the tune is to blame.
i dont think he would even change much in the part throttle tune.
plus your o2s are still going to be adjusting.

what kind of emission test is it? idle or the dyno type

did you get a ses light when you pulled the relay?

it might be that the cats arent heating up, it they are after the y-pipe on a long tube car thats pretty damn far.

 

I dont mean to highjack stealth formula's thread but we seem to have the same problem.
to answer your question blkchevyz, I'ts a dyno type test, and no I did not get a ses light when I pulled the relay. You may have a point about the cat being to far back. I appreciate your info

 

i didnt have a problem getting my cammed car to past with long tubes and 2 cats right on the collector. it actually did the quick pass.
but thats a foot or two closer then then after the y

 

I agree, it's probably not your tune stealth, there's not really much to adjust fuel wise that's not WOT related in a mail order tune.

You can change the MAF tables to get rid of part throttle fueling issues but that is very cer specific and I know for a fact madz28 does not do that.

If your car is running rich at part throttle or idle it is NOT a tuning problem.

Only thing I can think of is having the air pump disabled, but that's not really a standard thing to do either.

 

Start off by giving us they actual #'s and the limits of each HC, CO, Nox
I used my stock tune with Pacesetters and dual small bullet cats and just barely passed. Its possible that your single cat is not efficient in its location and remember that the universal cat is less eficient than stock in emission reduction to begin with. The EGR is going to be your next obstacle because theres not enough back pressure with headers for the valve to function. Ion can give you a header EGR tune thats supposed to work. Generally the tuning will lean out the stock fuel curve as GM runs them rich. Lastly when you live in a location that has emission testing with the sniffer its in your best interest to keep your stock pcm for that purpose.