pre cat?

killer_1986

just wondering what the pre cat is? keep seeing alot of posts about removing it, will this increase power at all?
also what other free mods can i do as ive lost my job and have alot of time on my hands but no money!
i want to make my engine quicker but want leave the outside standard apart from some alloys.

Matt

It's definately recommended to remove the pre-cat, does free up a bit of power.

De-restrict the air box also.

si_c1978

check out some of the how to guides cheers

killer_1986

i cant afford to get a high flow panel filter so should i go old school and drill the air box? also was thinking bout removing the centre silencer and welding a straight pipe in its place?

si_c1978

there should also be a how to guide somewhere in the forums for deristricting the standard airbox, check that category, cant beat a good viper mind.....

JohnnyN

Leave the centre pipe! The only gain there will be noise. Drilling the airbox is fine but do it on the inner wing side and not the engine side. You could also add another large hole at the front of the box and then add another cold air feed. The precat removal is a very good mod and its completely free.

;-)

MikeS

also eliminates the possibility of it falling apart and blocking your cat which is very hard to diagnose

killer_1986

cool i think i will remove the pre cat then! is there a how 2 with pictures on here i found a text one but would like to look at some pics before i try anything. cheers fo all the help eveyone! cheers..

si_c1978

download/file.php?id=1301 this should be the link you need, make sure you disconnect your battery when you start so the ecu will re-learn when you've finished and empty your downpipe well. dont be alarmed by the lumpy running (you will be) it'll clear up over a 20-30 mile drive(don't exceed 3000 revs) and make sure you got a good amount of fuel (canes it while re-learnig) :thumbup:

si_c1978

porting and polishing your throttle body is another next to freebie (if you feel up to it, if not i would get a spare throttle body to practice on if your not confident) i can post you a link on how blue22se did his(i used this)
or i gather vocky does a mint job for a good price send him a message.
also check the links on blanking off the egr valve while you have all that gubbins off. :mrgreen:

killer_1986

hey cheers for the pre cat removal download very good write up and easy to follow, im surprised any exhaust gasses can escape with that crap blocking it!
ive ported the throttle bodys on my 2.0 and 1.8 vectras i assume its the same for the 2.2?
will the ecu definatly re learn or is there a chance it will get stuckin limp home mode?

MikeS

ive ported the throttle bodys on my 2.0 and 1.8 vectras i assume its the same for the 2.2?

the x20xev and x18xe engines are cable driven where as the 2.2 is fly by wire so u have to be careful how close u get to where the butterfly sits and is positioned at idle as they are more sensitive

you don't have to reset the ecu, I didn't when i replaced my cat [pre cat already removed], the ECU will relearn but it will take a lot longer than actually unplugging the battery

by removing the pre cat there shouldn't be any reason for the ECM to go into limp mode as the only sensors affected are the front and rear lambda's

neither of them put the car into limp mode as the ECM will use stored Reference voltage's [.45 volts], the EML will pop up after about 5 - 10 miles of driving

killer_1986

cool think im gonna try removing the pre cat and try porting the tb if it ever stops raining!! gonna av a go at adding the traction control switch too seems pretty simple im sure i got a spare switch somewhere!

si_c1978

good luck..... ive just been getting wet mostly this year i was doing the 2.4 manifold yesterday!