Changed my tune resistor, what diffference?

[Bomber Denton]

I removed all the cats from the 500 recently and the ECU has been running in cat mode. This week I have changed the resistor for a euro non-cat setting, not driven it yet will it make much of a difference?

[David Beer]

Super smooth even pull, even poodling at at low revs, not much popping on over run and a slightly sounding "flat". Well thats what i found, but i had just the main cat in.

[blitzracing]

Dont forget to reset the DC voltage for non cat on the airflow meter. 1 -1.5 volts to keep the low speed mixture correct. With the cat setting of 1.8 volts it may run a bit rich.

http://www.g33.co.uk/fuel_injection.htm

[blitzracing]

I have tried fitting a 3.9 TVR chimaera catalyst chip to my non catalyst car, and measured the fueling to see if the non cat map is as good at the cat map. It appears to run very lean above 4500 rpm, and shows all the charateristics of being the standard Range Rover fuel map. Bad idea.

[Chassis 33]

Would TVR go to the extent of putting extra maps on the ECU other than the one to suit the particular car the ECU was destined for? I reckon that you could have the 1 correct map and the remaining 5 are as they left the (Land)Rover factory. This is all my presumption, however, and maybe contacting Power, Mark Adams or the like would give a conclusive answer.

Regards
Iain

[GreenV8S]

Chassis 33 said:

Would TVR go to the extent of putting extra maps on the ECU other than the one to suit the particular car the ECU was destined for?

I don't know, Mark Adams almost certainly does. I seem to remember from his comments in the past that it was something that you shouldn't rely on, but I don't remember whether this was in the context of the TVR map or ones that had been modified subsequently. Mark's point iirc was that Mark's chips always had the full complement of maps set every time but other chips might not.