scooby red

iTrader: (2)

Hi, Ive just had my bug sti remapped today and happy with results. (318/315) my mapper noted that the neutral pos sensor was faulty causing the torque to drop off a little and suggested i replace the sensor then get him to check it over again.
My question's are should i decat the second pipe before i map again and what peoples thoughts are regarding decats at MOT time? What gains will i see/notice?Do i refit the cat pipes for mot(pain in ***) or find a friendly/blind tester?

Current spec is 2002 STI uk, decat downpipe,racebox back box, green panel filter, hrc 255 fuel pump, 3 port boost solenoid, racedynamix remap 318/315.
The 2nd cat and original centre pipe are still in place.
cheers

Midlife......

iTrader: (2)

It's the downpipe that passes MOT so if it's missing then I'd simply de-cat the lot

The NPS causes AVCS issues so needs sorting and likely re-mapping

Shaun

r1c

iTrader: (9)

As above! What's the point in keeping the 2nd cat, if the 1st has gone. It's never gonna pass mot anyway

dynamix

iTrader: (3)

Agreed Shaun - might as well bin the centre cat too and swap one back in for mot purposes when needed.

Yeah re the AVCS issues, I explained and demonstrated that to Dave today. Will just need checking and a possible tweak for the mid range where the avcs cams were jumping out of it and causing a drop in torque. Will def need a map tweak if the centre cat is no longer there Dave

JPC500

I had a de- cat and constantly had the Check engine light on, a code reader would clear it and within a couple of days would be back on again. Also had to put on a proper cat for the MOT so in the end I couldn't be arsed anymore so got rid of the de-cat, didnt really notice any power difference to be honest

Midlife......

iTrader: (2)

It's easy to map out P0420 (no cat), the main problem is finding a MOT

Shaun

scooby red

iTrader: (2)

OK duncan cheers, will give you a call when i'm all sorted. i noticed a massive difference driving home in its current set up, so looking forward to further map to iron out nps issue and losing second cat. cheers, dave

scooby red

iTrader: (2)

thanks all for advice

dynamix

iTrader: (3)

No probs. Speak soon.

jason62

iTrader: (2)

guys, just reading this thread. ive got a sports cat down pipe to be fitted soon, on my turbo 2000.
but gonna keep the centre cat in place. ( coz my neighbours have been complaining to each other about the noise, but no one has the guts to do it to my face ) so will this be ok for the mot due in september????

Berks-Jack

iTrader: (10)

Yes mate it'll be fine, as long as the sportscat is a good un. It's the cat in the downpipe that passes or fails the mot. You may aswell remove the 2nd cat as your exhaust won't be any louder by removing it.

SkydiveMacca

Then get a quieter back box. Job done

scooby red

iTrader: (2)

https://www.scoobynet.com/general-te...ed-on-mot.html


Just read this.

hoyty

Strange scooby world leave the centre cat in and still
Pass mot and only loose about 5 hp .only saying what they told me when I was up there enquiring about some bits and pieces

scooby red

iTrader: (2)

I thought it would be a pass with centre cat in also(prior to this years eu changes!) thats why i left it in!
I guess it comes down to the tester's interpretation of the new regs. Looks like many more scoob drivers gonna need a friendly tester.

hoyty

If you read the tests new regs the tester is supposed to look on the data base to see how many cats are fitted and then physically count them as well as the co2 test and on the wrx that includes the up pipe

chopperman

Pro's.
more flow so some power gain if mapped.
Con's
noise
hassle getting an mot with the new rules
higher % of harmful gasses in the cabin due to un catilized gasses caused by burning benzine in unleaded fuel.

I think a sport cat is the only way to go.

SinghSuperStud

iTrader: (2)

How likely is the cabin gasses issue?

I am decatting my up-pipe on a bugeye and ocassionally may have by 14month old in the car and don't want to impact her health

chopperman

I once read an article that pollution can be three times higher in the cabin than it is curb side due to lack of ventilation. Whether this is gasses from the car your in or other cars i don't know.
This article was in a paper written by some professor about 4 star leaded vs unleaded petrol. His findings were the lead in the old petrol was so heavy it fell to the ground within a few feet of the tail pipe and was unlikely to be breathed in by anyone.
Unleaded was a different case though. The noxious gasses caused by burning the chemicals in this fuel namely Benzine were being pumped into the atmosphere and were extremely harmful and even carcinogenic. This was the reason catalytic converters needed to be used to convert these harmful gasses. The problem though was catalytic converters dont work until they reach about 400*. So until the cat has reached this temperature you were exposing yourself and others to these gasses. Some car manufactures started to put pre heaters in the cats for this very reason and it could be the reason why Subaru put them in the down pipe as they will heat up very quickly in this part of the exhaust. It may also explain the change in the law regarding de-cat vehicles.