Mazda Rotary Club

General => General Technical => Anything Engine/Performance/Tuning related => Topic started by: nikp on March 05, 2004, 12:58:54 PM

Title: I think my pre-cat has died
Post by: nikp on March 05, 2004, 12:58:54 PM
Hi all,

I suspect that the pre-cat has gone in my FD, but am not sure. Under heavy load, the car sometimes feels like it\'s holding back, but appears to be generating the sort of boost values that i\'d expect. This mostly happens in higher gears, and/or at higher revs. I have also had the \'Heat\' light come on a couple of times under heavy loads.

Does anyone have any idea of how to confirm whether or not the pre-cat has gone? If it has, what are my options, and costs involded? Would a Pre-Cat replacement pipe be adviseable (Mods are HKS induction kit, and some sort of free flow exhaust - not sure if the main cat has been removed, but i suspect so) I\'ve heard tell that if the pre-cat pipe is replaced then I need to upgrade the ECU, is this correct or can i get away with not upgrading the ECU (I\'d rather not have to buy a downpipe at £300 ish, and then the ECU at £500 ish - I\'m not that rich!!!!)

Cheers for your help.
Title: I think my pre-cat has died
Post by: bobster on March 05, 2004, 01:22:29 PM
I\'m not entirely sure but Geff at reworx told me that the imported FD\'s don\'t have precats.
Title: I think my pre-cat has died
Post by: Jovic82 on March 05, 2004, 01:27:59 PM
not too sure on that one
got a second hand cat available though if you need it.


Cheers
Nick
Title: I think my pre-cat has died
Post by: richrx on March 05, 2004, 02:26:15 PM
imports have no pre cat that was only the uk spec cars which had em.

you may have a BIG problem if you have a free flow exhaust and an induction kit, also if the cat has been removed then even more so.

Dont  drive WOT until you know for sure. With 2 mods affecting the rotary\'s breathing you NEED an ecu.

maybe someone with more knowledge could step in but you may damage your engine if you dont get it checked out.

rik
Title: I think my pre-cat has died
Post by: nikp on March 05, 2004, 03:33:37 PM
Admittedly I have only assumed here, but because I have been getting a Heat light come on (Only a couple of times) then I figured I have []some[/i] sort of CAT. Maybe I just have a main CAT then. I\'ll check at the weekend!
Title: I think my pre-cat has died
Post by: nikp on March 06, 2004, 08:16:50 PM
Ok, so I have no pre-CAT and I have checked for the existence of a main CAT which I have found IS present. Could it be that that has desintergrated? Could that be responsible for the problems I have been experiencing?

Cheers, Nik
Title: I think my pre-cat has died
Post by: Jus on March 06, 2004, 08:26:39 PM
@nikp

Hi mate...

Do you loose boost? Your main cat could be blocked.

Failure could be due to simple usage or your air pump may have failed.

Should you need to replace the cat, do so. My advice is not to fit a cat replacement pipe due to fuelling/boost issues with stock twins.

Let us know how you go on mate.
Title: I think my pre-cat has died
Post by: Jovic82 on March 06, 2004, 08:29:07 PM
you mentioned holding back. i had the exact same feeling when i ditched my cat and had a straight through pipe. got the ecu done now aswell and it feels a lot better but as jun said dont go for a striaght through unless you wanna upgrade your ecu.


cheers
nick
Title: I think my pre-cat has died
Post by: Jus on March 06, 2004, 08:38:36 PM
Thanks nick...

ECU then consider the cat replacement pipe.

Jus
Title: I think my pre-cat has died
Post by: Jovic82 on March 06, 2004, 08:44:58 PM
thanks i just hope i wont live to regret my decision of leavin it quite so long to get the ecu!!!!!
Title: I think my pre-cat has died
Post by: Jus on March 06, 2004, 08:52:29 PM
Wouldn\'t worry, have you had a tune up, on wide-band.

If you have then happy rotarying, the rotary tends to tell you straight away if she feels unhappy.

You haven\'t heard a sound like a bag of spanners under your bonnet have you? If not, smile...

Jus:D :D :D :D
Title: I think my pre-cat has died
Post by: Jovic82 on March 06, 2004, 08:55:30 PM
i havent had it pproperly mapped yet but thats coming this week.

apart from the holding back i mentioned she seemed to handle pretty normal. had new engine put in six thousand ago so hopefully all is well ;-). no spanners yet!
Title: I think my pre-cat has died
Post by: Jus on March 06, 2004, 08:58:48 PM
Good and GOOD...

;)
Title: I think my pre-cat has died
Post by: michal marzec on March 08, 2004, 07:26:17 AM
would i get away with installing a straight thru mid pipe (cat replacement pipe) if i left the original back box.
Or would it still run too lean? :confused:
Title: I think my pre-cat has died
Post by: Jus on March 08, 2004, 09:45:32 AM
I would say yes no problem because you still have decent back pressure by with keeping the stock cat back. And it would save you £££ on a replacement cat (until MOT).

You can always get another opinion though, as I have not seen this working.

Jus