Cats removed, do I need a re-map...?
Discussion
the_ferret82 said:
possibly... you would see some power gains if your decat and a after market exhaust.
there will be others that will know better on later
there will be others that will know better on later
Well since the de-cats and straight through pipes have been fitted low down torque has definately dropped. I'm wondering if putting the cats back in may help???
The Seer said:
the_ferret82 said:
possibly... you would see some power gains if your decat and a after market exhaust.
there will be others that will know better on later
Well since the de-cats and straight through pipes have been fitted low down torque has definately dropped. I'm wondering if putting the cats back in may help???there will be others that will know better on later
Your ecu can only make adjustments between set minimum and maximum values, so it cant make a full adjustment to allow for increased fuelling required at a set rpm, hence loss of torque as you maybe running lean at low rpm's. A remap will help but come mot time you need cats fitted and the non cat remap might fail emissions even with the cats back on. For the gain its not worth it, a friend had a full longlife system fitted to his vxr8 with sport cats and it sounds mental.
TorqueTalk said:
Your ecu can only make adjustments between set minimum and maximum values, so it cant make a full adjustment to allow for increased fuelling required at a set rpm, hence loss of torque as you maybe running lean at low rpm's. A remap will help but come mot time you need cats fitted and the non cat remap might fail emissions even with the cats back on. For the gain its not worth it, a friend had a full longlife system fitted to his vxr8 with sport cats and it sounds mental.
Yeah had this once before when I remapped my 182 Cup, cats re fitted but failure on the MOT. However I went elsewhere for my MOT after that
. Not to happy about the possibilty of running lean though.
the_ferret82 said:
The Seer said:
the_ferret82 said:
possibly... you would see some power gains if your decat and a after market exhaust.
there will be others that will know better on later
there will be others that will know better on later
Well since the de-cats and straight through pipes have been fitted low down torque has definately dropped. I'm wondering if putting the cats back in may help???
i belive the tune will just have to be adjusted to allow for the extra air flow but the easy and cheeper option would be to put the cats back.. IMO
Well, that may be on the cards, really unsure as to where to go from here.
Assuming the car will be running in CL mode, using the front 02 sensors (fitted before any CAT) to control the fuelling, the ECU will attempt to maintain Lambda 1 using the 02 sensors by oscillating around the switch point between rich and lean to maintain stoich. I bet removing CATS is not going to make the car run 25% lean which I believe is the upper and lower limit of the fuel trim corrections so a remap should not be necessary but who would want fuel trims that high?
I imagine without CATS all the emissions will be way outside an MOT pass as far as I can see based on my own experience running CATS where they need to be bloody hot to keep the car within limits.
What are you trying to achieve by running no CATS? I assume more power? Surely just stick a cam in?
I imagine without CATS all the emissions will be way outside an MOT pass as far as I can see based on my own experience running CATS where they need to be bloody hot to keep the car within limits.
What are you trying to achieve by running no CATS? I assume more power? Surely just stick a cam in?
TorqueTalk said:
Your ecu can only make adjustments between set minimum and maximum values, so it cant make a full adjustment to allow for increased fuelling required at a set rpm, hence loss of torque as you maybe running lean at low rpm's.
As per above post by Mr Substitue this is not correct by a long shot.nosubstitute said:
Assuming the car will be running in CL mode, using the front 02 sensors (fitted before any CAT) to control the fuelling, the ECU will attempt to maintain Lambda 1 using the 02 sensors by oscillating around the switch point between rich and lean to maintain stoich. I bet removing CATS is not going to make the car run 25% lean which I believe is the upper and lower limit of the fuel trim corrections so a remap should not be necessary but who would want fuel trims that high?
I imagine without CATS all the emissions will be way outside an MOT pass as far as I can see based on my own experience running CATS where they need to be bloody hot to keep the car within limits.
What are you trying to achieve by running no CATS? I assume more power? Surely just stick a cam in?
I imagine without CATS all the emissions will be way outside an MOT pass as far as I can see based on my own experience running CATS where they need to be bloody hot to keep the car within limits.
What are you trying to achieve by running no CATS? I assume more power? Surely just stick a cam in?
Yeah, that was the idea, just a cheap way of extracting a little power plus increasing the exhaust note. Didn't really fancy swapping the cams due to the cost. Luckily I've kept the cats, and may have them put back in if that's causing the trouble.
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