Lorenfb

As long as you don't have a CAT and aren't worried about emissions, & don't have
a check engine light, disconnecting the O2 sensor has the following benefits:

1. generally a smoother idle
2. a little better throttle response
3. can run a little lower AFR for a little better performance

This is the case for stock chips.

special tool

And if you live in a cold climate and follow the above advice, you will NEVER start your car without cleaning your plugs everytime.

I have my idle at 19:1 right now. My lambda is connected and working perfectly. The Motronic can only keep you at 14.7 in closed loo[p if you are within a certain range. Once I bring it down to aboput 16, the Motronic locks on and brings it to 14.7. My car idles perfectly at 19, and is VERY clean.

Fact, not fiction.

awilson40

Did you adj your idle mix down with the piggyback
I never thought of that, How low do you have to go before the motronic wont, cant bring it back up ??

special tool

That's what I mean- when I lessen the injector duty cycle at idle to a point leaner than around 16:1, the Motronic drops it and can no longer bring it to 14.
My car likes to be around 18 (when it is warm)

SO, when I sart the car, thge lambda will put it at 12 for cold (I have watched this on wideband), then when the lambda comes on, it goes right to 18:1.
I never have a problem at cold start because by the time the lambda comes on, everything before it (head) is warm enough to run at 18:1.

toddk911

So don't disconnect the O2???

I think this is where the discussion was at a long time ago. Some say yes, some say no

Lorenfb

"SO, when I sart the car, thge lambda will put it at 12 for cold"

Lambda doesn't function when it's cold. The water temp sensor must get below
a certain value before the system goes closed loop.

So:

1. when cold, O2 sensor connected/disconnected is a "don't care"
2. when warm, running depends on CO setting (AFRs) without the O2 sensor
3. when at WOT, "don't care" about O2 sensor

Bottomline: Well adjusted DME fuel maps or AFM setting and no CAT,
and a disconnected O2 sensor is not a problem (except for emissions),
and might provide better performance.

toddk911

How do you adjsut the CO2 setting?

awilson40

I still have the stock VAF, do you think I could adj this with the mix screw
in the VAF without messing up the rest of the maps?
Or should I try to take the idle map down in the EPROM ?

Frank@Work

The result so far:



Stock K26/6 running ± 14.7 psi with ReliaBoost
Lindsey Racing dual port wastegate
Delphi 65lbs/hr injectors with ballast resistors
Stock exhaust without the cat
Pro-M Maf with PowerPerfect fuel controller (NOT SMT6 PerfectPower)
Guru Racing chips

This month I will put the LR 3” exhaust back on and head for a dyno.

Frank@Work

The numbers below are all crank numbers! Boost was set at 15 psi.

stewardx

Todd. If the car runs better with the 02 unplugged then leave it unplugged.

NZ951

Todd, if you car runs better with the O2 unplugged, find out whats wrong and fix it!

PS Frank, you get too rich too quickly in the lower rpms. That will be effecting spool...

toddk911

Actually I have never run without it. Just curious to know the pros/cons in running with out one.

Frank@Work

Yeah, your right! Already dealt with that one. I try to stay around 13:1 untill 2750 rpm.

Frank@Work

For adjusting the "just cruising" AFR I unplug the O2 sensor. This way I can see what the result is of the initial amount of fuel injected without the DME adjusting it. I will try to get as close to 14.7:1 as possible. When finished adjusting I reconnect the O2 sensor and the DME has a pretty easy job getting the right amount of fuel into the enige.