Hello Chappies, had my car MOT'd yesterday and it nearly failed due to corrosion (read: leaking) on the down pipes. The garage has managed to patch them up so that the car passed but it has given me the perfect opportunity to fit De-Cats.

 

I have searched on the Forum for info on the Cat removal but i am unsure of how much work is involved. Is there anyone out there that can give me a blow by blow account of how they removed theirs.

 

I've been told by the garage that they are unsure what to do with the AIV hoses (pre-cat) and also the sensors just after the cat (Temp sensors?).

 

The De-cat i have includes the turbo elbow and my car is a 91TT J-Spec.

 

Any help is greatly appreciated. Ta

there are people on here that will know about this, but in the mean time i would suggest talking to Luke at the Z centre, he sells the downpipes and knows a lot about the sensors and how it all works

Hi fella,

I've just had mine done for £140 all in, that's s/steel too. Pro-Speed in Cardiff did it and the guy's name is Charlie 02920 461444. I know it's a long way from Watford (About 2 hrs) but well worth the money and the power difference is unbelivable. http://www.pro-speedexhausts.com

If you decat just remove the AIV valves or block up the pipe that used to goto the exhaust.

Cheers Gents. Cardiff is indeed a long way away from Watford, but thanks for the info. I'm sure this would be a a good one for the FAQ's when done. Anyone done the work themselves?

Hi Mark

Just a few things I learned whilst decating my tt.

I bought the kit from e bay and very nice it was to, so I fitted it, not to bad to do,

remove battery to do n/s and brake mastercylinder to do o/s top bolts ,then from under the car remove cats heat sheilds and the tricky bit the lower manifold bolts ,

get a good 13 mm spanner for the job cos if it slips or snaps your in a world of grief.

change the o2 sensors to the new manifolds ,not to bad as there in a brass bush so they dont just snap of like I thought they might,then bolt it all back up.

No problem? yes problem, A week later they are leeking on the manifold gasket,so today I took them off again to find the flange faces that bolt to the turbos had

warped to leave a gap for gas to escape on each end ,when checked with a steel rule

about two mil,also the two bolts holding the seperating block in had come undone.

So after flating the flanges and locktighting the the two bolts in I used a high temp

gasket sealer when refiting them and at last all is well.

Next time Iwould check the flatness of the flanges , locktight the seperating block allen bolts and use a hi temp sealer on the manifold gaskets.

Live and learn I guess.

Thanks, Timbo. I'll certainly take all of the precautions you said about. Did you strip the AIV equipment off of the car completely or just blank off the hoses?

 

Also, what did you do with the two sensors after the Cats?

 

Cheers, Mark

HI Mark

The aiv stuff had allready been stripped of my car but I believe you could do either.

as regards the temp sensors I just tucked them out of the way anywhere I could but they can be cut off if you like , Ijust kept mine incase I ever need to put the cats back on.

Oh by the way they dont wanna come out I had to resort to the gripwrench attack.

Good luck.

Unless they've shifted the goalposts again, emission tests don't apply to 10 year + vehicles.

Thanks for all the help Gents. Was the AIV strip out tricky? When you took them off do you have to plug hoses on the engine, disconnect plugs etc.?

Not sure why O2 sensors were mentioned as you wouldn't normally go near them if just doing a decat - they're further forward on the turbo downpipe/manifold.

 

The cat temp sensors can just be unscrewed and shoved back through the wire hole to under the carpet. Fill the hole with a rubber blanking grommet. You could just cut the wire of course, but you never know, you might find a use for them one day.

Not sure why O2 sensors were mentioned as you wouldn't normally go near them if just doing a decat - they're further forward on the turbo downpipe/manifold.

 

 

Split dumps with test pipes, not just a pipe in place of a cat.

Hi Mark

Just a few things I learned whilst decating my tt.

I bought the kit from e bay and very nice it was to, so I fitted it, not to bad to do,

remove battery to do n/s and brake mastercylinder to do o/s top bolts ,then from under the car remove cats heat sheilds and the tricky bit the lower manifold bolts ,

get a good 13 mm spanner for the job cos if it slips or snaps your in a world of grief.

change the o2 sensors to the new manifolds ,not to bad as there in a brass bush so they dont just snap of like I thought they might,then bolt it all back up.

No problem? yes problem, A week later they are leeking on the manifold gasket,so today I took them off again to find the flange faces that bolt to the turbos had

warped to leave a gap for gas to escape on each end ,when checked with a steel rule

about two mil,also the two bolts holding the seperating block in had come undone.

So after flating the flanges and locktighting the the two bolts in I used a high temp

gasket sealer when refiting them and at last all is well.

Next time Iwould check the flatness of the flanges , locktight the seperating block allen bolts and use a hi temp sealer on the manifold gaskets.

Live and learn I guess.

Tim, how long did it take you to fit them?

Split dumps with test pipes, not just a pipe in place of a cat.

 

 

Ah, gotcha - didn't spot that first time round.

Well yaz I spose it must have taken me a good 8 hours thats with a four poster ramp

a very comprehensive set of snap on tools and a teenth to stop me loosing my rag.

If the manifold bolts come off ok then ya laughing,shit if they dont,so about 15 to 20

cuts and bruises and one black eye from a 1/2 drive ratchet hitting me in the face and 8 hours just about did it .

Anyway, its much more fun and interesting doing it yourself regardless of pain.

Anyway, its much more fun and interesting doing it yourself regardless of pain.

 

I agree, im yet to fit some but it's happening this weekend, need to replace the centre bearing so tackling the full zorst same time:cool:

Well yaz I spose it must have taken me a good 8 hours thats with a four poster ramp

a very comprehensive set of snap on tools and a teenth to stop me loosing my rag.

If the manifold bolts come off ok then ya laughing,shit if they dont,so about 15 to 20

cuts and bruises and one black eye from a 1/2 drive ratchet hitting me in the face and 8 hours just about did it .

Anyway, its much more fun and interesting doing it yourself regardless of pain.

 

 

Me too - I bought the new turbo elbows/decat delete kit from ebay as well and it fitted like a glove - very happy with the quality - took me all weekend with the car on jack stands, that included 3 hours trying to get the O2 sensors out - gave up in the end and just bought new ones! AIV's out at the same time. :)

 

 

yea straight forward-ish job to do,

 

 

theres 2 bolts at the the start of the downpipe, then 2 bolts at the end of the down pipe (cat is at the end of the downpipe)

 

 

as someone mentioned, just either bug up the pipe that goes to them, or just remove the AIV completely.

This'll be fun later in the year when I do mine along with the new/upgraded tubs :D

I'm sure it'll be easier as I'll be having the engine out as well :bow:

thinking of doing mine soon...BUT i have heard so maney people say about turbo seals going.what bhp do you expect to gain with a de-cat.

i have had no problems in the past with de-cats on skylines and supras WHY..the 300zx.

Well yaz I spose it must have taken me a good 8 hours thats with a four poster ramp

a very comprehensive set of snap on tools and a teenth to stop me loosing my rag.

If the manifold bolts come off ok then ya laughing,shit if they dont,so about 15 to 20

cuts and bruises and one black eye from a 1/2 drive ratchet hitting me in the face and 8 hours just about did it .

Anyway, its much more fun and interesting doing it yourself regardless of pain.

 

 

Hahaha, very true, stick a few stronbows in there and your laughing :rofl::duffer::smash:

...It's also a good time to change the rear gearbox mount and the prop centre bearing - while the zorst if out of the way and the thing is in the air...