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What if I just disconnect the EGR & AIR Systems in my LT1?

What will happen to your smog checks, and our air?
Just a simple question.
HP is easy to find.
I just saw this thread. I can’t believe more folks have not jumped in!!!;shrug

1st. You need 3 wire, (heated), O2 sensors. With out Cats you will never get the O2´s hot enough to work. No voltage out of the O2 = NO closed loop = Bad gas mileage.:(

First of all Thanks Spanish for your advice;) . Since my vette is an LT1 it has heated sensors: two on each pipe before the cats and one after the right cat (or where it used to be) I have all three same way but now in the long headers.

The temperature advice is good. With a 160º T-stat and the stock chip I doubt that you will see much closed loop time.

My vette PCM has a flash memory, not the prom chip. That's the main reason I had to buy the Hypertech ten months ago and now my PCM has been programmed for the 160 Tstat and the some other mods that are in my signature at the start of this thread(like the rear end ratio change).

After you install the heated O2 sensors the stock prom might pull the mixture back into tolerance. If it was my car I would hold off on the new prom until you have finished all of the mods you plan on. Most of the prom burners will re-burn the chip a time or 2 for free but it is still down time while you send the chip away to be re-programmed.

I think you're right, but if only one of the sensors is after the cats (the one down stream at the right side) maybe that's the one I need to change for a dummy O2 sensor, then start tunning and wait for the last mod before I have the PCM re-programed for a professional! :D

It's good to hear from you Spanish, If you have more ideas post them! (and that way this thread will stay like Ken says:^^^) :L

The main reason to keep posts coming is that as you see I'm in need of more than one answer!

:w George
Do a search for ¨field service mode¨ I remember reading about jumping 2 pins on the ALDL to check the open / closed loop mode but I do not remember where it was posted.

Thanks, I'll search for that!:upthumbs

(Now I have homework) :L
tazdevl35 said:
Hello George,

Let me see if i can clear up some of this confusion....first , the cats are gone correct? You will need to put the O2 sensor eliminators in place of the O2 sensors so the computer will see the correct values...that is to say the ones it would normaly see if the cats were in place.

Taz :t :t

Yes, they are gone. ¿Do I need to change two sensors or just the one after the cat? (stock there's only one after the right cat).

Second... you have headers on the car now and have eliminated the stock manifolds with the AIR tubes that go to the AIR pump ....this is fine as long as the pump solenoid is disconnected the pump wont dump air out of the tubes that went to the manifolds...however, I would remove the pump as well and use a shorter belt..the pump is drag on you accessories and if its taking 2-4 horsepower to run it ,

Yes, I have now long tube headers that came with no AIR System tubes, but the AIR pump in the LT1 is electric, it does not have a belt so it's one less trouble. I just disconnect it and closed all the AIR tubes with rubber. But I don't know if the PCM receives any signal or something from the electric AIR pump that can cause any code. ;shrug

As far as mileage goes the O2 eliminators will help with this but keep in mind without "live sensors" in place the mileage will never be as good as it could be because the computer cant fine tune the mixture.But it will be better with the eliminators in place.

I read somewhere some time ago that the "before" cats O2 sensors are the ones that take care of the fuel-air ratio, and the "after" cats O2 sensors where there to control the emissions system. I'm not sure about this but what's your opinion? Because if that's truth I'll just need one eliminator and it wont hurt too much the mileage!

As far as the ASR system....asr retards timing and backs the throttle off for slip regulation....you could have removed or bypassed something necessary to the proper operation of the ASR system. With out actually seeing what you have there i cant offer any help in that area. Once you have done all these things, clear any codes and start over. You will need to reprogram you computer with someting besides hypercrap. I have used their products and they didnt "blow my skirt up" so I would have a custom program designed and flashed into your PCM. This is the best and only way to get the best performance out of the mods you are doing.I always recommend to everyone to do mods that are emissions legal, high flow cats, emissions friendly cams,etc. This makes life so much easier...or better yet install a better exhaust and a supercharger kit....you still get reliability, mileage and a kick a$$ power increase. I know its more expensive but I prefer the tried and true methods that work with the on board systems.

I swear I didn't touch it! Do you think it can be related to the MSD ignition control module? it even makes the tachometer go crazy between the 3,000 and 3,500 revs! I think is the multy spark thing. And, ¿what about the code 72?

I'm sorry Taz, too many questions. I'll let the rest for tomorrow!
Everything I want for my vette is emissions friendly this is not the way I've planned my mods but that's for other thread!

There's only two more mods I would do: The ATI Procharger and/or the LT4 Hot Cam Kit!

Take care Taz!

oldace84 said:
What will happen to your smog checks, and our air?
Just a simple question.
HP is easy to find.

I'm from/live/drive in Guadalajara, México. The smog checks down here are not obligated but voluntary once each year. I did it the next day I took off the cats, last february and the vette passed.

I took a stupid choice in a hurry at the mufflers shop (I was there to get the Magnaflows changed from my L98 to the LT1) the vette had 28 K and I did let them (the cats)for the trash can(they where almost new)!!! :duh :hb I shouldn't be posting this and let you all know how stupid I can be sometimes but it's done!!!

Anyway, that's why I need help to get the vette tuned and fixed the best way I can with what I have, so it contaminates the less!

This thread has nothing to do with more HP (I went south when I took off the cats, that's the reason for this thread)

Thanks Tony, you gave me the chance to clear it (I hope I did it)

Any ideas are welcome!

See you!

:w George

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