Decat fuel map

[Hamburglar]

For MOT, just stuck my standard catted Y piece back in my car, and compared to the full ACT decat ive been running(manifolds + Y piece), it feels much pokier all the way through the rev range.

Ive never changed the tune resistor on the car, and just wondered if any of you guys have, and what the results you had with your decat setups?

[Hamburglar]

Anyone?

[daveb500]

I've not tried it recently. I had an ACT decat pipe at one point and switched to the pre-cat setting. It ran much smoother at low revs but had problems under full load and smoked a bit so I think it was over fueling.

I've now got the full ACT headers with no cats but haven't tried switching it. I was trying to find out from Mark Adams which setting he recommended (I've also got a Tornado chip) but I didn't get an answer.

From the people I've spoken to, the general concensus seems to be to continue to use the cat setting because it self-adjusts. But it can result in shunting if it has to adjust too much.

[blitzracing]

daveb500 said:

I've not tried it recently. I had an ACT decat pipe at one point and switched to the pre-cat setting. It ran much smoother at low revs but had problems under full load and smoked a bit so I think it was over fueling.

I've now got the full ACT headers with no cats but haven't tried switching it. I was trying to find out from Mark Adams which setting he recommended (I've also got a Tornado chip) but I didn't get an answer.

From the people I've spoken to, the general concensus seems to be to continue to use the cat setting because it self-adjusts. But it can result in shunting if it has to adjust too much.

Spot on, plus the non cat map is not tuned for the car, its likely to be a Range Rover map or like.

[Hamburglar]

Thanks for the input guys, did either of you find (or have rolling road evidence) a power difference between catted and non?

[blitzracing]

I only had evidence on a 3.9 TVR cat map v's a 1992 Rangie map, and the TVR map gained 20 bhp on an otherwise untuned RV8 engine, from 180 bhp to 200. No so much the TVR map was good, but the Rangie map was bad at higher RPM.

[daveb500]

I didn 't try it but there was no point because there were clearly issues with the pre-cat map.

[Hamburglar]

Great thanks guys, looks like I shall keep my car the way it is for the mo.

[v8s4me]

I've been trying to get hold of Mark Adams for 6 week without response as well. Is he man or myth?

[blitzracing]

A post from Mark last week on another issue......

Although I rarely look at Pistonheads these days, I've just spotted this. I'm sorry for the lack of response to all my Clients, but I am simply swamped with messages and enquiries. I get around 20-30 messages a day, and most of them need very detailed individual answers. There simply aren't enough hours in a day to cover them all, so often you need to be persistent.