jonno

Hi Guys, and JDM Sti 7 owners

Just to let you know that after 3000miles running being a full decat, the car has now finally decided to throw the CEL!!

Did not expect it, and was stuck in slow moving traffic at the time.

But why now after all this time would this come to light?

Thanks in advance Jonno.

TonyBurns

iTrader: (3)

Errrrrm probably cos your engine is about to explode!!!
Running a full decat on an STI7 (esp a type uk) will push your boost to 1.7 bar somewhat a little high for a scoob.
Would suggest that you re fit your cat and hope that you aint done any permanent damage to your car!

Tony

Razor2001

Hmmmm, Tony,

I thought that people had solved the boost spiking issues with a 1.25mm restrictor. I think that a few max boost at 1.26 bar now with a full decat from turbo back......am I wrong ?? Bretman, others ??

Cheers,
Ray

Hey, Jonno do you still have the modded uppipe on and do you have the CEL fooling gadget installed ?

Dave T-S

Jonno

Do I seem to remember you recorded a 1.8 bar spike a week or two ago?

BretMan

Probably just the rear o2 sensor decreasing in efficiency and falling outside the standard boundaries for the system with a cat.

Talk to Pete at Scoobysport, he will sort it out with his black box of tricks which modifies the rear o2 sensor signal.

Deep Singh

'Your engine is about to explode'.Perhaps you should look into the details a bit before you come up with such melodramatic diagnoses.Out of all the engine failures on Scoobs over the years how many people were warned with a CEL? I think the answer will be zero.

GDB

For what it's worth:

Ever since I decat my JDM STi 7, the CEL came on twice if I remember correctly. In both times, it was when I was driving very slow at a constant speed, or cruising in the highway at a very leisurely speed.

That CEL must be just a reminder that an STi is not meant to be driven slowly.

Oh BTW in both occasions I just ignored it; turned off the engine, left to do whatever business I needed to do, by the time I started the car the CEL had disappeared.

TonyBurns

iTrader: (3)

Deep,
Running 1.8bar of boost will indeed make your engine explode (totally wrecking it) so its not melodromatic, its fact.
Also the CEL is a warning, it can mean many things but it is still a warning that something is not right
Running a decat on any turbo car will cause problems, and until those problems get ironed out you have to look at the most severe consequenses of your actions (which was overboost on my car) and BIG boost spikes on the STI7.
I dont think everyone who now has a fully decat STI7 will also have a 1.25mm restrictor plug fitted to their car, in which case you go back to the last thing that you did to your car before it pulls up any warning lights etc

Tony

mutant_matt

Tony,Well, not quite. I would imagine it would take a while to do some proper damage from 1.8 boost spikes, it's obviously dangerous and needs addressing quickly, but you should quantify your statements a little better . Holding 1.8 however, would be a different matter.....True. It can be many things, but not usually a sign of impending doom. Very often it's because a sensor has broken or is reporting out of range. It's how you act on this information that can make all the difference. Until it's checked out, you should drive gently in case it's a "real" problem. If it goes away by itself, it's usually because said sensor is reading correctly again.Do you not think that that is a little melodromatic? How many people must there be out there with a full decat and no issues? Must be hundreds!!! Just because you had a bad experience, does not mean that your particular mod is "dangerous" or "risky".You won't get a CEL just because your boost is too high and in Jonno's case, mostly, his boost control issues have been solved, but he is still working on refining it. And there has been a shed load of discussion about boost control on the STi 7, the thread is currently running at something like 15 pages so it's not like people don't know about it.....

Just some observations,

Matt

Big Goon

Had my 01 WRX decatted and didn't fit the 02 sensor mod for about 2500 miles when the cel came on for the first time, that was at a leisurely speed too.

Get the 02 mod from SS, I've had mine for about 8000 miles now, no probs at all.

jonno

Thanks Guys,
Ray, i have still the SS up pipe on, but have never had the o2 sensor fitted........ although i have got one never had the need to fit it.

Dave, i recorded a 1.8 bar boost spike and again the next day a few weeks ago....... its down to the weather conditions etc it did calm down again, but have been playing with a few restrictors that MrC sent to me!!

Bretman ... Exactly my initial thoughts.

I do think it is possibly o2 sensor, but seems a bit weird that it should show this 3000+ miles later, good to hear Big Goon had his CEL 2500+ miles later too........ so it is a possibility!.

Will have it checked as soon as i can get to a select monitor!!

Tony, my CEL is one issue, the boost spikes are another, i know there are problems re o2 sensors with full decats, i just think its strange that it should throw the CEL from nowhere after such mileage......... unless its not the o2 sensor.

Cheers Jonno.

Deep Singh

Tony,I did'nt mean any offence its just your statement was a bit sweeping if you know what I mean.As Matt explained the boost spike issue on the Sti7 is an ongoing discussion on this bbs.1.8 bar held boost would of course be disastrous on the STi,however I d'ont beleive the CEL has anything to do with it.Two seperate issues.On my previous STi4 I once had the boost up to 1.5 bar held,it was detting like mad and no CEL.I think it would be lovely if the CEL did warn us of impending engine failure but I d'ont beleive it does.