down pipe and de-cat

[Nev_LCR]

done a search but cant fine anything on this,

if i was to get a down pipe and decat, will i have running problems or lights on the dash??

cheers

 

[skahigh]

i think you're car would fail the mot on emissions and as such would be illegal, maybe even invalidating you're insurance?

 

[Nev_LCR]

thats not a problem, just need to know how it will run and if the dash will light up without remap

 

[skahigh]

hmmm, i am totally guessing here but i would have thought if you are buying a decat exhaust system there would be no lambda probe to allow the ecu to adjust fuel/air mixture.....

on the other hand there are guys that run decat, i cant see how that works

someone more technical than me want to explain?

 

[Eternal Rage]

i de-cated my 1.6, and yes the engine management light came on. It ran OK, if a little on the rich side ....

its due to the oxi sensor being 'post cat' unlike a lot of cars where it is 'pre cat' and hence doesnt make much difference...

 

[skahigh]

i thought there were two probes, one either side of the cat so the ecu can tell if the cat is f****d.

 

[Nev_LCR]

cheers for the info, would like to here from someone with an LCR as there maybe some differences in the de-cat,
cheers

 

[karlosR]

send arosaracer a PM, he has a decat on his LCR but its with the standard downpipe. i think he had his second lambda sensor mapped out.

 

[chriswilks]

following remap &filter my lambda is being a pain!!!keeps coming up even after being replaced!engine light is on permanently and runs odd at high revs,gettin 2nd sensor mapped out soon as!!as for decat wouldnt know either.dont think the ecu will like it though??

 

[StuLCR52]

running race cat on my LCR had fitted over a year no engine management lights but u will need to map out the second sensor if u go completely de cat,

ive a rossi race cat n it was 4 times the emissions on the mot! that was sorted by a piece of tricker in front of the cat......

 

[Nev_LCR]

cheers guys, this is all the info i found on the search, i take it there is no one running a downpipe and de-cat on a standard LCR then?????

 

[Mitchy]

You'll probably lose a bit of power due to fuelling issues and you'll create more lag as your turbo will not spool as well as you need a bit of back pressure in the system. You'll trade off some low down torque also! You'll also have an engine warning light headache!

Gone are the days when you used to modify japcrap and gain 30bhp or so. Not nowadays!

There was a big issue a couple of yrs ago when a £1000 exhaust system actually lost the car power due to being ''too free flowing'' Many members were fuming. Made the car run like a bag of sh*t aswell.

Like i said, waste of time and effort! Get a sports cat and keep a little back pressure in there.

BF 3'' DP and 100 cel cat is a popular choice and proven!

 

[RobM]

There have been a few people on this forum who have lost a load of torque and power when running a de-cat. Expensive way to slow the car down IMO. Good safety feature though

 

[Nev_LCR]

my reason for asking is i just got a decat for my rs and it made a masive difference even with the standard system, so whats so different with the lcr

 

[StuLCR52]

difference is ur rs most likely didnt have the second sensor aft cat, which the ecu reads and adjusts settings too, LCR will not run well without a cat! as the first sensor and the second sensor require different signals n with decat these signals to the ecu will be identical, even with mappin etc it is still gonna run like ****. your best option is a 100 or 200 racing cat, my rossi racing cat sounds awsome at full chat n it runs perfectly.

i'm not saying this is the only reason it will run **** with decat this is how its been explained to me. it cud be mapped to run decat but u run the risk of losing torque etc which is my belief on this as ive seen this happen.

im not an expert on this, so if ive made a boo on this i do sound like a tit but hey this is how it was explained to me.

hope this helps ur decision

stu

 

[Mitchy]

my reason for asking is i just got a decat for my rs and it made a masive difference even with the standard system, so whats so different with the lcr

Your going to lose low down grunt with a decat, your losing back pressure! K04 turbo starts struggling at 5000+rpm so losing low end grunt on standard turbo along with gains in lag is definitely not reccomended.

Do as you please though, ignore everyone and just go for it Let us know what you think. The hassle with ECU light and MOT along with the above makes it a no brainer for me! Sports cats are fairly cheap £250ish and you wont get any of the above^^^