Blairc

Guys,

I’m looking for some solid answers on the question of does decattting a PPP`d car work? As I’ve got a `99 PPP scoob and have read many posts all with good and bad stories on this topic. I’m a bit worried that it might cause my car to start over boosting and may even have detrimental long-term effects on the engine.
So I’ve got a few questions:

1. Why does the PPP ECU not like being decatted while the standard one doesn’t seem to mind?
2. Will I need a knocklink to monitor the car if I go for this modification?
3. Could it have any long-term effects on the car i.e. turbo problems, running lean etc?
4. Lastly but no mean least would people with a PPP`d car that have had it decatted please give me there feelings on what it did to their cars, both good and bad?

Sorry for the long post and your help is well appreciated.

Chris

AvalancheS8

Pretty much all the info you need is in this thread, in which you have already had a discussion with a couple of people who know their stuff.

Blairc

Avalanche,

Strictly speaking no it hasn`t. Questions 1-3 still remain unanswered in the post that you have you have made the clicky to. Agreed that question 4 has been answered by a few guys I would still like a bit more feedback on what other people`s experiences are on this matter. Thanks for the help anyway.

AvalancheS8

I disagree, from reading that thread I would say that the answer to question 1 is that it's to do with the restictor, not the ECU directly, it causes a problem because the PPP ECU removes some of the built in safety margin of the std ECU in exchange for more performance so it needs to be set up more carefully.
Also from reading that thread you will see that several people are saying that you should have at least a boost gauge and a knocklink, preferably also an AFR gauge before you start making these mods so that you can see what's going on because, yes, it could start to run lean and have problems with det. So the answer to question 3 is that yes, it COULD have problems in the long run, but if you get yourself the necessary monitoring kit and set it up carefully, with help from a knowlegeable person if needed, then you can run it that way pretty safely. Don't remember it being mentioned there, but there should be no problems with your turbo if you use good oil, change it regularly and warm the car up and down carefully.

STi wanna Subaru

iTrader: (1)

good post

The_Judge

The time it's taken me to type this, AvalancheS8 seems to have already made the main points, but **** it, I'll post it anyway...!

1. Why does the PPP ECU not like being decatted while the standard one doesn’t seem to mind?
The PPP ECU maps were designed specifically with the rest of the PPP package in mind (which includes leaving the cat in the downpipe). The boost pressure levels are higher, and the ignition timing is more advanced than the standard ECU. When you remove the cat in the downpipe, you're improving the volumetric efficiency of the engine, which in turn creates slightly more boost pressure than the enhanced maps are expecting for a given load/rpm, which then causes the problems that some people experience. The re-drilling (or replacing) of the restrictor helps the ECU control the boost pressure better, in most cases eliminating the oscillation altogether. A 3-port wastegate solenoid can also help.

2. Will I need a knocklink to monitor the car if I go for this modification?
A Knocklink is a good idea, whatever modifications have been made. Personally, I think it's a good idea to get a Knocklink prior to modifying, so you can get used to what it's telling you. Same goes for boost gauge and AFR gauge.

3. Could it have any long-term effects on the car i.e. turbo problems, running lean etc?
Turbo problems - no.
Running lean - as long as your MAF sensor is healthy, and the restrictor bore has been enlarged, you shouldn't have any problems whatsoever. But that's where your Knocklink becomes essential. AFR gauge as well, to a degree, but unless you also replace your standard lambda sensor with a wide-band, you can't rely on the information the gauge is providing you with. But this and definitely this on a Knocklink, that only ever used to display this, can be wholeheartedly relied upon...

ARM-Scooby

TSL will re-mapp so it accepts it!

AvalancheS8

From the other thread it looks like he want's to avoid re-mapping. Personally I'd be looking at a Dawes or similar or an add on electronic boost controller to control the boost better while leaving the PPP ECU intact.

chris singleton

Was PPP and decat a problem on newage cars?

I've been running this setup on my bugeye for nearly a year now. I've got boost, oil pressure and boost gauges.

cheers

Chris.

Blairc

Guys,

Please accept my apologies if your having to go over the same ground again – I think it`s a case of not being able to see the wood for the trees in my case!!
Avalanche – just re-read my initial post to you and it sounds a bit OTT, sorry it wasn`t meant to be. Your also completely correct about me wanting to keep the Prodrive ECU as it is. I want to try to keep the car with all the PPP parts standard so I`m really left with just changing the other bits.

The judge – when you talk about the wide band lambda sensor can a standard AFR still read the output that one of these sensors gives out?

Thanks again guys

zenyck100@hotmail.com

i have a PPP ECU and am about to decat the downpipe. if i get overboost will a dawes device control it? if not has anyone got a picture of the location of the brass restrictor that i would have to drill out. (il get some made by my friend so i can put the standard one back in if need be to save drilling)


cheers


Zen