PD 130 to decat or not to decat?

[pauldazzle]

My A4 is booked in to Prospeed next week to have the cat insides removed, & a pipe welded in to keep it looking OEM. Just wondering if anyone on here has decat'd there PD, & their opinion on the results.

 

[deano1978]

I only have the cat by the turbo,middle and back boxes removed.
I've never read or heard of a definite answer to this Q

 

[SL11CKK]

Ive heard in numerous tdi forums not to decat as the turbo on ours need back pressure. Something about boost spike as we have smaller turbos.

Hence I still have my poxy cat.

 

[pauldazzle]

There seems to be a lot of conflicting views on the turbo back pressure issue.

 

[pink.teg]

Yer just ask Charlie , think my cat is gone just got 2 back bboxes left
its done the job !!!
Alan
say u know Chinese Alan he may knock abit off for sure !!

 

[Gaz!]

I went to have mine remapped, the company refused to map it as they said the turbo wouldnt last long. I have now reoved it. They said without the cat the turbo spikesand will certainly fail.

 

[beachbuggy]

I went to have mine remapped, the company refused to map it as they said the turbo wouldnt last long. I have now reoved it. They said without the cat the turbo spikesand will certainly fail.

I imagine they refused because they have generic maps designed for cat cars, by removing the car you make it freer flowing and possibly will cause issues, simply as they are not capable of adjusting the map to compensate for the cat removal. I'd suggest you go somewhere that actually maps rather than just flashes a generic map!

main issue with removing cats or larger DP is the back pressure which goes somewhere to helping sealing the rear oil seal, it only assist by having a higher pressure outside the turbo than oil pressure inside and thus pushes the oil/keeps it in. By making it freer flowing you reduce that and can cause oil blow by..

 

[@udi A3]

Decatting makes naff all difference to power, darkside kindly kept that info from me before taking mine off and chargeing me for the privalidge

 

[pauldazzle]

As per my research there's no definitive answer, just disagreement.
My own experience with decatting a Mondeo ST220 TDCI asskicking was that it made a big difference. Spool up was a lot quicker, & throttle response improved. I didn't see it as power mod, but as a driveability mod.
Maybe wrongly I was hoping for the same from doing it to the Audi.

 

[pauldazzle]

Well the cat is gone, & it's made a very noticeable difference. Much smoother & feels more responsive. The cat was seriously sooted up, & partly blocked! Gave it a good blast & the black smoke was unreal for a bit, but cleared after a few redlines, & if anything there's less smoke than before. Charlie reckoned the cat was just about shot so as I suspected 188K had taken it's toll.

Pleased so far & will update in a few days.

 

[Stu-pid]

I need to do mine but I'm gunna knock it out if I can

 

[Mollygoogle]

My 130k PD 130 has been decatted for about three months, the difference was instant! The car pulls much better without it. As said above smoother and more responsive.

Decat, K&N Panel, DTUK Tuning Box all adds up to 178bhp. Just got to decide what to do next

 

[deano1978]

Guys... What did you use? custom pipe or hammer?

 

[Mollygoogle]

Guys... What did you use? custom pipe or hammer?

AUDI A4 1.9 TDi Turbo Diesel 2000-2004 Decat Cat Bypass | eBay

 

[666markyboy]

I imagine they refused because they have generic maps designed for cat cars, by removing the car you make it freer flowing and possibly will cause issues, simply as they are not capable of adjusting the map to compensate for the cat removal. I'd suggest you go somewhere that actually maps rather than just flashes a generic map!

main issue with removing cats or larger DP is the back pressure which goes somewhere to helping sealing the rear oil seal, it only assist by having a higher pressure outside the turbo than oil pressure inside and thus pushes the oil/keeps it in. By making it freer flowing you reduce that and can cause oil blow by..

Thanks BB...... finally an answer from someone who knows about turbo's.... your explanation makes total sense

 

[deano1978]

So you wouldnt advise this mod??

 

[Mollygoogle]

Mine runs brilliantly with it done, as do many others

 

[pauldazzle]

Really glad I had it done, the car feels absolutely great. Best £50 I've ever spent on a car.

 

[Jacko1]

How did you turbo hold up in the end with the de cat .....any issues?

 

[Gazwould]

 

[pauldazzle]

I eventually sold the car with 240k on it & it never had any turbo issues after the decat.

 

[Gazwould]

I'm impressed..

Frees up back pressure , only issue is stinky exhaust and slight turbo whistle , which is kind of in keeping with a Euro 3 car , with a Euro 5+ it wouldn't fit .

 

[Jacko1]

View attachment 205062

PMSL - yeah it was an oldie but it needed to be to get a good idea of the long term reliability : )