Two Step & FAST

[SEFi8LOxCivic]

Does anyone have a two step running on their FAST?

Craig, if you're reading this, I know when we spoke you said to setup the closed loop enable point above the two step activtation RPM to avoid a falsly rich condition detected by the O2 sensor, but I've been talking with a pro class import racer who also runs fast, and I was wondering if I could run his idea by you.

How he does it is he keeps the closed loop rpm where it normally resides, which is 1200 give or take. And instead what they're doing is retarding timing by a lot on the cell where the Two Step activates. This appearently allows him to build boost on the line without the fear of having a lean condition occur due to the falsly rich condition read by the o2.

Any thoughts or comments on this?

Thanks.

 

[Craig Smith]

This is basically two different issues here; here's my thought.

What you are referring to is a trick used by some turbo racers to improve spoolup time on the turbo. The concept is that if you retard the timing down to nothing, you will actually have fuel burning in the header pipe. The increased exhaust heat as a result of this is supposed to make the turbocharger build boost faster.

When you have a 2-step activated, it won't necessarily read rich - it might read dead lean. It is unpredictable. Bottom line is that a misfire (which is all a 2-step is) will produce erratic readings from the O2 sensor. I know some people who even say that the 2-step doesn't bother their O2 sensor! You just never know. Either way, regardless of where you run your ignition timing, if start dropping ignition pulses your O2 will most likely hate you for it and misbehave.

 

[89TURBOTA]

craig, so if i am leaving at 4400 on the two step , what should i put the hi and lo closed loop rpm limits?

by the way my car made a 9.58 @142pass last friday

thanks
www.chiseledperformance.net

 

[SEFi8LOxCivic]

Craig,

i have another buddy who came up with this idea for the two step...

"While on the 2 step I am in open loop. I am sure you are aware of the settings. my open loop high is 6300, and then open loop low is 2000. Basically what happens is that I am in open loop until 6300 rpms (my 2 step is set at 6000), once 6300 rpms are exceeded it goes into closed loop and doesn't go back into open loop until the rpms go below 3000. So anytime at idle it goes right back into open loop and it's ready to get on the 2 step again. Yes the timing is retarded in the cells that apply. It works really great. It will turn some heads that's for damned sure. Especially if you are at a light and just want to mess with people Lol! It's down right obnoxious!"

This sounds good right?