93 LT1 emissions problems

[84MONTESS]

Hey everyone, Ive been having some serious issues trying to get my car through Delaware emissions and was hoping someone could shed some light on my problem. The car is a 93 formula firebird, stock lt1 with long tube headers and still has a cat on it as well. I recently did a tune up on the car after it initially failed emissions twice in stock form before the headers were put on. Amazingly enough the car had the original opti on it right down to the cap from 93 and was still running quite well, however it was failing hydrocarbons by 234ppm, the limit in DE is 220ppm and CO's are 1.20ppm. So I replaced all the ignition components, opti, wires, plugs, coil and icm as well as waterpump, thermostat, coolant temp sensor, new heated o2's and also a egr delete since the headers did not have a provision for it. I just put brand new 22lb injectors and a fpr on the car at the recommendation of a local shop which did help the car some however now the car is failing worse with hydrocarbons now at 705ppm and CO's at 1.31ppm. This is also only happening on the idle test, the car passes the the high idle test with flying colors. I have searched the forum till my eyes hurt reading posts of other members cars that had similar problems and now at a loss at what to do. Any help or advice is greatly appreciated, thanks in advance.

[popo8]

Talk to our tunning guys. They may be able to tell u what to look for in a data log and what to adjust in the tune to clean it up.
MoeHorsePower

LTXtech.com IS my drug...

[84MONTESS]

I'll give them a shout , thanks man

[uncool]

It failed twice in STOCK form, so you put long tube headers and on ORY with a cat some where in the exhaust? Your cat is most likely too far back in the pipe to get enough heat to do its job at idle. You have a leak in your exhaust upstream of the O2 sensors. Then you threw a bunch of parts at it hoping to get it to pass.

Not trying to be a dick, Look at my sig. I have a FULL emissions 93 in CA and my last smog test my HC at idle were 37 and 11 at 2500 rpm.

A little more info on your car would be helpful. New cat, in the stock location? Or is it way back in the merge of the ORY?

[BALLSS]

OP, as noted in the above post, your long tube headers puts your CAT to far back to light off and burn as it should so your HC's are high. Even if you have lose emission testing in terms of visual (here in Calif you would fail on that alone even if pure oxygen came out the exhaust)

a tune may be able to lean it out enough but the CAT will struggle to get hot enough to burn off spent exhaust enough to pass. Really the whole purpose of "shorty" headers...it keeps the CATS close enough to burn off

you could try a new CAT and 02 (AC Delco)...might get lucky

[jaysz2893]

I'm in delaware and having the same problem now too. Last time I went through with the exact same setup I passed with no problems. Now hearing this I am really thinking they do not have a clue how to do the test right. We need to talk.

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[84MONTESS]

I'm in delaware and having the same problem now too. Last time I went through with the exact same setup I passed with no problems. Now hearing this I am really thinking they do not have a clue how to do the test right. We need to talk.

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I was hoping you would see this post man, I read the thread you had your car and the results seem unfortunately similar lol. As for the other questions yes the cat is brand new and tbh the location of the cat was a concern to me simply because there is no close place to put it with the y pipe merging so far back in the exhaust. The 02 sensors are brand new as of the day of the original post, I had done the heated conversion the night before. The reason for replacement of the other items was not out of strictly to get it to pass but because they were all well pass there life span and I simply like to keep stuff in proper working order. The last thing I want to do is throw parts at it, that's why after much consideration I did take it to a good friend of mine who has 40+ years of automotive experience in emissions testing. I went by his shop on Friday after work and looked the car over again and is starting to think there is either a small vacuum leak or possibly a valve that is not adjusted properly. Thanks again for everyones input on this.

[jaysz2893]

I was hoping you would see this post man, I read the thread you had your car and the results seem unfortunately similar lol. As for the other questions yes the cat is brand new and tbh the location of the cat was a concern to me simply because there is no close place to put it with the y pipe merging so far back in the exhaust. The 02 sensors are brand new as of the day of the original post, I had done the heated conversion the night before. The reason for replacement of the other items was not out of strictly to get it to pass but because they were all well pass there life span and I simply like to keep stuff in proper working order. The last thing I want to do is throw parts at it, that's why after much consideration I did take it to a good friend of mine who has 40+ years of automotive experience in emissions testing. I went by his shop on Friday after work and looked the car over again and is starting to think there is either a small vacuum leak or possibly a valve that is not adjusted properly. Thanks again for everyones input on this.
I adjusted the valves and checked for vacuum leaks and still failed. The 3rd time thru at DE City the dude admitted he didn't know how to do the test. I still failed. Pm me here and we can catch up. I'm in the Odessa area. I'm currently looking for someone with fresh eyes to look over my crap. I am planning on waiting till 2016 to tag it. Get 2 years and then go for antique.

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[Spartan7]

OP, as noted in the above post, your long tube headers puts your CAT to far back to light off and burn as it should so your HC's are high.

Depends on where the cat is. I was able to pass the ridiculous CA sniffer test with LT's and high flow cats.

[SJx408]

Spartan7 in theory one could pass smog in CA with LT's and reg universal cats with a "smog cam" and a really spot on tune?


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[Spartan7]

@Spartan7 (http://ltxtech.com/forums/member.php?u=980) in theory one could pass smog in CA with LT's and reg universal cats with a "smog cam" and a really spot on tune?

I passed with LT's with emissions hookups, high flow cats, all emissions equipment in place, LE2 heads, and a 222/230 112 cam. Now, this was back in 2010 before the STAR crap came out, I've since moved out of the state so I can't comment on how it is now. It was also illegal to have LT's on my car at that time, but I had a guy that would "overlook" that as long as all emissions stuff was in place. That was also with a crappy PCM4less tune, and I barely passed. A better tune would have had no problem.

[84MONTESS]

I was able to get the car to pass emissions last Friday once we put a new cat on the car. The old cat was defective or clogged up somewhat, because once we put the new one on my numbers dropped a lot. Thanks again for everyones input on this problem, this forum has some really good info when it comes to LT1's.

[jaysz2893]

I think I may invest in a new set of cats next year. I still hate DE DMV

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