decatting question

[slideways]

Hi All
I'm a little unsure on something,
If i completely decat the manifolds and y piece but keep the lambdas do i need to fit the green tune resistor and if so why??
Thanks
Rich

[StreetDragster]

Nope, if you run completely decated, but retain the lambda sensors you use the white tune resistor so that you still have closed loop fueling control.
The green tune resistor is generally for people who decat the car, but remove the lambda sensors.

Thanks

Matt

[slideways]

thanks for that it can all get a little confusing at times for us technicely chalenged types
ta
Rich

[blitzracing]

The green map does put in more fuel, and the low speed response is better, but you will visit the pumps more often. It will also muck the main cat' up if its still fitted.

Mark

[slideways]

I,ve just purchased a nice shiny pair of stainless manifolds and y piece all decatted.
and intend to keep the lambdas in so all i need to do is stick the old y piece back on come mot time.
or should i loose the lambdas as well and change the resistor? how much performance would i gain from this? again keeping the catted y piece for the mot?

Edited by slideways on Sunday 27th July 23:55

[blitzracing]

Id keep the lambda's in place. If you run the catalyst fuel map without catalysts, you really loose very little, the only problem can be a slight snatching at around 1500 rpm in higher gears, but the fuel consumption is lower. If your car does not snatch now, its probibly going to be OK as is. The non cat fuel map puts in a bit more fuel, and you will need to set up the AFM with a CO gas analyser to get the mixture spot on (The lambda's will do this on the cat map automatically.) The extra fuel does give you fractionly better instant pickup, (This is due to the fractions of a second the ECU takes to switch from closed loop catalyst map, to open loop full power loop) and generally the engine can run cooller, but its all pretty marginal. Full power is unaffected either way. Its pretty easy just to wire 2 tune resistors and a small switch under the dash, so you can switch fuel maps when you want for the best of both worlds.

Mark