I'm setting up my 86 Fiero S.E with a V-6 and a 5 speed for track racing for the SCCA. I'm looking to remove the entire emission system and I was wondering if anyone has successfully removed everything and still retained the reliability of the engine? I've got the hanes book so i can remove all emission items but will the car run the same as it did before? If anyone has done this or has a good idea on how any infromation would help alot.

The only real emissions hardware are the EGR system and the catalytic converter.
The cat can be removed with no ill effects (except for a possible loss of low end torque, which will likely be compensated by a small gain on the top end. YMMV.)

The EGR system can be removed and blocked off.
The programming in the chip needs to be changed to make the "EGR enable temp" high enough that the engine will never see it.
The O2 sensor can be programmed out, as well, but you need to have your fuel tables tweaked to make sure that you are running an acceptable air/fuel ratio in "open loop".

Edit - You can also replace the PCV system with breathers, but I don't think it'll be worth the trouble.

[This message has been edited by Raydar (edited 01-13-2007).]

Thanks the rules state that I could remove the emission system, and i was just trying to figure out if it would actually be worth the trouble of removing everything and tuning it to run with out it.
Thanks for the responce, anything further would be apprecated.

There are small gains to be had with removing the cat, or better for the environment, replacing it with a modern low restriction unit. The performance difference between a modern one and no cat at all can only be found with very sensitive measurements.
A larger improvement would come from removing the restrictions in the exhaust manifolds though. Then doing something about the cat would make a bigger difference.

Removing the O2 sensor would be a step backwards in terms of performance.

[This message has been edited by Jax184 (edited 01-13-2007).]

quote Originally posted by Jax184: ...Removing the O2 sensor would be a step backwards in terms of performance.

I wasn't really suggesting that it be done. Just that it could be done.
I've seen it done in a Fiero race motor (by a professional dyno tuner, strangely enough.)
It really wasn't pretty. Although it goes like hell according to the driver, it fouls plugs horribly. "Pig rich" doesn't even begin to describe it.

I'd be pretty surprised if there were any benefit in removing the smog stuff. I don't think any of it is power robbing.

Yeah ok that makes sence that it wouldn't be smart to remove, would you happen to know the optimal air/fuel ratio I've been told that alot of the stock settings are pretty much the best that they can be set. again thanks for the info

GM really did do a great job on the Fiero's ECM. It's set up to get virtually every drip of performance possible out of the unmodified engine. Fuel curves and such really arn't worth messing with until you've changed the engine enough to warrent it.

proper fuel air mix is a continuously variable number, dependnet on engine load/rpm/etc.

Since you are going to be racing it, the cat can go, as well as the egr. the ecm will compensate for the egr, just leave the solenoid in place, and cap the vac line to the old egr valve. A minor improvement in hp. (small but it is)

as was mentioned, the exhaust logs are severly restrictive, and can be fixed internally and reweleded for strength, and still be stock. the y pipe also has a restriciton at the Y, see Dodgerunners yet another 3.4 build thread for a nice pic of the problem.

fix the exhaust, remove the cat, and egr, and that's about it for performance without going non stock and out of class.

Once i get everything removed i'll try to get up some dyno numbers with a stock motor and no emission just to see what the actual gain is. Also once i start makin some progress i'll put up pic's and a detailed discription of the build up in another post.