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Anyone M5'ers out there with a J.Comforti chip, Dinan chip or some other chip unplug their 02 sensor after they installed the chip? I hear some talk about getting better performance since the 02 works against the aftermarket chips. Anyone have personal experince with this?

[QUOTE="Crazy Croat"]Anyone M5'ers out there with a J.Comforti chip, Dinan chip or some other chip unplug their 02 sensor after they installed the chip? I hear some talk about getting better performance since the 02 works against the aftermarket chips. Anyone have personal experince with this?[/QUOTE]

I have a Conforti chip in mine and my sensor is still plugged in. I don't see how it would benefit as the O2 sensor keeps the car running at an ideal air-fuel ratio. or am I crazy?

Frank Fahey suggests the same thing while running a track pipe. I have tried it, with the O2 sensor unplugged my MPG drop by about 4 MPG, but it did smooth out the idle. I did not notice any big improvements in performance, I have a dinan chip and exhaust cam sprocket.

If you still have the Cat installed on your car then running without the O2 sensor will destroy the Cat in short order.

Yea I figured as much. No I dont want to kill the stupid Cat .... yet... I actually passed Emissions testing with ease here in NJ. (Before the chip was installed) I like my MPG too. I think I will leave it plugged in.

I have a http://www.powerchipgroup.com/choices.a ... roup%2Ecom in my M30B34 and it requires the lambda to be disconnected. Plug that puppy back in and she runs like a Kenworth on biodiesel.

'course I've gas-axed the CAT too. I just don't spend too much time around the back of my car while the engine's running sniffing the pure toluene coming out the pipes

I just installed the Fahey track pipe yesterday. I have the JC chip and I left the O2 connected at first. Even with it O2 connected I could feel the difference without the cats. Then I unplugged the O2 sensor and it really changed the car. The idle is much smoother and the slight lean surge at part throttle is completely gone.

Mileage used to be about 18 mpg average for me. I'll bet I get less than 16 this week.

Devinder

That pipe cost you a pretty penny.. I forgot what Fahey charges for it but I know its not cheap. Where are you located and how are you going to get around Emissions testing?

It takes about 15 min to change out the pipe for test day. The cats were starting to get weak so I look at it as a $500 investment to keep from spending $1200+ later.

I got something roughly similar but shorter on the downstream end. The Euro-spec non-CAT cars had the big long sausage muffler from the E12 in there for the front muffler. It starts basically straight after the bend where that underside silver reflective heat shielding is.

Your heat shielding looks like mine. Still grotty with the wax coating on it. I've got to drop my exhaust and give it a jolly good clean up soon. It's supposed to be bright shiny silver to reflect the heat downwards.

Umm,
There should be no hp gain from unplugging the O2 sensor. The ECU runs open loop @ WOT.

In fact, you may hurt hp, as the adaptation factors are applied to all operating areas. If you unplug the O2, the adaptation values may be skewed in ways that hurt your top end power!!!

RussC