Do i need a remap again?

jase125

Active Member
Nov 16, 2013
51
0
Had my exhaust (full system with decat) fitted yesterday well happy with it! but will it need remapping again because the cats out? it doesn't feel as quick as it did with the standard system on? I'm just wondering if it will need mapping again? Cheers.
 

D1andonlyantman

Active Member
Dec 5, 2013
410
1
You should get any and all mods done before you get remapped because engine mods will change the AFR, throwing the map off. I'm a motorbike man so don't want to pretend I know everything about cars, but as far as I know going decat really changes the flow rate through your engine meaning the air/fuel ratio isn't right. that's why it feels down on power.
 
Last edited:

jase125

Active Member
Nov 16, 2013
51
0
No the car had a remap before i put the 3" downpipe on with decat and the rest of the system
 

chrispcupre

Active Member
Jul 27, 2011
767
9
leicestershire
No the car had a remap before i put the 3" downpipe on with decat and the rest of the system


I would get it on a dyno to check how it's running , I reckon it could be stage 1 as I don't think any one would tune it any further with the cat on IMO If it is then it's going to feel rocket powered with your mods if you stage 2 it :)


Sent from my iPhone using Tapatalk
 

jase125

Active Member
Nov 16, 2013
51
0
Well the engine light came on last night so took it to mate today and it was something to do with the cat it thinks its still got it in! It needs mapping again! :(
 

D1andonlyantman

Active Member
Dec 5, 2013
410
1
Are you sure it's not the post cat lambda screwing coz of the really high emissions, because I've heard that happens when you go decat. You can buy a spacer or turn it off with a vag com I think.
 

jase125

Active Member
Nov 16, 2013
51
0
not sure, i know both lambda sensors are plugged in! but its where it was mapped with the cat in now its de catted it still thinks the cats in
 

D1andonlyantman

Active Member
Dec 5, 2013
410
1
To be honest mate it's probably because it thinks the cat is nackered because of the really high emissions. You can buy a spacer which will stop the lambda reading such high emissions or actually turn the post cat lambda off which will stop the error. The pre cat lambda helps sort the AFR, the post cat is the just to make sure the car is running as it should be and because you've removed the cat it thinks there's a problem. That's how I understand it anyway, I could be wrong.
 

jase125

Active Member
Nov 16, 2013
51
0
I see what you mean mate, but it dosnt feel as quick as it did with standard exhaust system on?!
 

D1andonlyantman

Active Member
Dec 5, 2013
410
1
That's probably because it's been mapped already it can't make adjustments to the map to make up for the decat so it's running lean. I'm not sure on this but if you get your car mapped and then the car decides the map isn't right, wouldn't it then start changing the map you just paid 300 odd quid for? Maybe when they remap your car it can't make adjustments to the map anymore so you putting on a decat has just really thrown off the AFR. I'm certainly not sure on that but it makes sense. I'm new to this so kind of at the end of my knowledge on the topic but I'm fairly confident the warning light is because of the emissions and the lack of power is because your AFR is off. A good tuner should fix the map and also be able to turn off the post cat lambda. Hopefully I've got that right and it's some help. As always any corrections are welcome, I'm here to learn and help :)
 

Richard123

Rickys LCR 225
Feb 4, 2013
169
0
Ayrshire,Scotland
Are you sure it's not the post cat lambda screwing coz of the really high emissions, because I've heard that happens when you go decat. You can buy a spacer or turn it off with a vag com I think.

yeah I think your right,I had down pipe and de cat done few months ago and eml kept coming on for cat efficiency below threshold.

I didnt think mine was any slower maybe a little quicker and little louder.:D

My mate deleted the cat eml with laptop, as he was turnig my boost down a little as it was spinking to 30psi and I didnt want to loose a rod!

I think it can be deleted with vag com too,as some one already said.
 
Last edited:

Seal_LCR

Active Member
Jun 4, 2012
2,600
5
Redditch
Awesome gti do an angled one I've been running it for a year as I've not finished the handling side yet before mapping
 
Adrian Flux insurance services - discount for forum members.